Educational Side of SML

Many of us who enjoy shooting simply want to load a firearm with a provided safe recommended load and fire away.
Then there are those that want to produce their own safe loads through reloading and fire away.
If the word “safe” is the key element and you don’t want to look any further or deeper into using smokeless powder then enjoy your time shooting. If you desire to possibly gain more knowledge about smokeless powder then I hope to open a door of understanding that I’ve gone through.

When I purchased my 10ML-II the owner’s manual gave you a guide line of recommended powders and bullets to use which I followed faithfully for a few years to get familiar with my equipment. After a while curiosity got the better of me how we could safely use such a fast burning powder as 4759 in a 50Cal?
Savage promoted the strength of their barrels for the 10ML-II and gave you a numerical value for pressures they could withstand. Yet they never mentioned what pressures their recommended loads would generate.

What really fueled my curiosity of “what gives” was others adapting other powders and duplex loads to safely reach even more heights with velocity. I finally reached a point of “I got to know” and began doing research of “Powder Burn Rates” and “Interior Ballistics”. Eventually a picture began to take form of what is really taking place in a bore when a shot is fired. What was missing was some way to monitor and record this now known activity in the bore. Hence I acquired a Pressure Trace Unit. The unit basically removed a blind spot by providing a visual representation of what is happening with a load when fired in the bore.

First thought with the mention of a pressure trace unit is it senses the amount of pressure inside a bore. It actually does more than that by providing the powder burn rate response and amount (not peak) of pressure a bullet load is exposed to that in turn affects final velocity.
This unit to me is also like a life line warning me not to venture to far or too deep into unknown territories that can be disastrous. For the price of the unit to me it basically is like paying a tuition fee for learning and that’s never cheap these days.

Below is a PT that shows the results for the pressure cycle of a 250gr bullet/sabot in a 50Cal with a load of 43gr of the old 4759 that came in a half pound can. Underneath the trace is some info PSI, Rise and Area. Velocity input is taken from a chronograph and added to the Trace Info separately.

Attachment 28527



Rise is the representation of the powders accelerated burn characteristic towards Peak Pressure for a specific load. There are a few more things that it can reveal but for our purpose we really don’t need to clutter our vision with them at the moment.

Area is a representation of the overall amount of pressure the bullet load is exposed to. This is important as the final resulting velocity is dictated by this factor. The larger the area-value the higher the resulting velocity.

Peak Pressure defines itself so no real explanation is needed here.

OBT Nodes (Sweet Spots) for a given load are shown as Red Diamonds along the bottom of the trace. When you follow the pressure outline you will see a small cross indicator appear on the outline indicating the bullet exit point. Here you need 2-info inputs into the program for it to appear and function.
1) The bullet depth from the muzzle.
2) The muzzle velocity of the load acquired from a chronograph.
With the above info the unit now can calculate the position for the sweet spot and exit point of the bullet load. The idea is to get the exit point directly above a node. So far it has proven to be pretty close to the sweet spot.

Any conveyed information is open to discussion or questions for clarification.

Ed

Quote:

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Originally Posted by ET1

For the price of the unit to me it basically is like paying a tuition fee for learning and that’s never cheap these days.

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Sort of like taking a course in Automotive Engineering to understand how to make your car go faster...probably not going to pay for itself because hwy's have speed limits, but interesting to know....actually I think there are a few University degrees that could apply to :)

Not sure if finding a sweet spot, in terms of your PT, is of much value if your not also considering the bullet and sabot as an integral part of the end equation for achieving the best accuracy (if that is your end goal?)

...ie...Finding the perfect powder measure to attain a perfect PT without considering the max velocity for a fixed bullet/sabot combination is meaningless if that doesn't also produce the best ballistic performance (accuracy) for that bullet.

It appears a lot of guys are pushing their SML's to achieve max velocities, to the point they have exceeded the ballistic capabilities of most of the ML .45s on the market and now are forcing themselves to using duplex sabots to be able to shot smaller/lighter CF rifle bullets to handle those velocities.

Eventually you hit the "Law of diminishing returns" and what have you achieved is meaningless. Pushing a 250 gr bullet to 2,400 ft/sec flattens out the trajectory.....but taking it from -88" drop at 500 yds (at 1280 ft/sec) to say -60" drop at 500 yds achieves what ?

Sometime it makes me wonder why guys are trying to make racing cars out of pickup trucks....LOL...

Just to clarify, I'm not condemning or criticizing your efforts Ed, I find them commendable and enjoy your posts and discussions, but as you said in your opening sentence, I'm one of the ones that trust the manufactures recommendation and enjoy playing around within those guidelines (rules ?) to discover the best powder /bullet combo that provides me the best accuracy I can expect for a ML hunting out to 200 yds. It never dawned on my till I read your posts to try and turn my ML into a long range sniper rifle...I have a .303 for that :)

Ed...I posted another thread about a product that lines the barrel with a lube that provides a 'ceramic' like coating to reduce friction of the sabot.

If in your efforts to develop a perfect PT sweet spot, for a powder/sabot/bullet combination, would using a dry lube in your barrel significantly alter the PT curve ? If the product claims to increase velocity by 2-5% would that have a significant effect on barrel pressures as there is less resistant in the load (sabot/bullet) ?

Mike Pal

I enjoy reading your comments and respect your point of view.
No university degree here just a grade-12 diploma but a lot of things learned from different exposures throughout my life time.

As for my eventual goal utilizing the PT unit and knowledge gained from studying Internal Ballistics is to produce some really good and desired safe loads for varying bullet weights for my SML. Along the way I have also debunked some myths that I once too was deceived by.
My goals already have been planned along with my approach to achieve them.
Major players will be my PT unit and chronograph showing me what is happening with my approach. Then applying what I learned from my study of Internal Ballistics this should help safely guide me to my goals.

I'm hoping that this early introduction will help anyone to understand some principles of smokeless powder usage and to be able to do their own analyzes when I start some PT’s later this year. Then when I share any load info I can also have some proof if they are safe loads should anyone want to venture along with their SML.

Yes I read your post on a product that reduces bore friction with ceramic usage.
Offhand I can’t see a real gain when using a plastic sabot but definitely in a rifle bore where bullet to bore contact is constant or sabotless shooting in muzzle loader.
As for your other questions I don’t have a definitive answer and can only hypothesize what the results would be. The only problem with hypothesizing is if you are proven wrong there are some sideline jumpers here waiting to pounce on your credibility. In this case I’m going to try and deny them this opportunity.

Ed

After rereading Mike Pal’s post the term engineering referring to technical aspect sort of hit home. When you understand a principle it no longer is complicated or confusing.
Okay I need to try to simplify a few points when looking at a PT.

So let’s start with AREA noted on the trace but first we need to understand why this is important. From Internal Ballistics we learn that a bullet is always under constant acceleration that is dependent on the remaining pressure behind it as to how fast this rate of acceleration occurs. As pressure behind the bullet begins to drop the bullet does not accelerate as fast but is still gaining velocity at a slower rate.

With a PT we can see and monitor the rate the pressure drops after it has reached its peak value. When a powder with a slower burn rate is introduced we will see that the decay of pressure behind the bullet is not as rapid as say with a faster powder that is consumed more quickly. The end result is higher velocity.
AREA on a trace is a calculated numerical value that represents the overall amount of pressure a load generates. With a higher value of AREA the more velocity is seen.

I’m going to keep RISE in a separate post to limit any confusion between the two.

Ed

Quote:

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Originally Posted by ET1

From Internal Ballistics we learn that a bullet is always under constant acceleration that is dependent on the remaining pressure behind it as to how fast this rate of acceleration occurs.

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Ergo my question ref the inertia of the bullet/sabot. If this dry lube has coated the barrel lands with a 'ceramic' film, then the sabot/ball combination will, if performing as theorized, accelerate quicker and at the same time provide less back pressure to ensure faster ignition of the smokeless powder.

With your PT graph, you should see a shift in the point of peak pressure if you alter any aspect of the load (sabot/bullet) or the condition of the barrel; dirty or hot or lubricated etc.

Quote:

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Originally Posted by MikePal

Ergo my question ref the inertia of the bullet/sabot. If this dry lube has coated the barrel lands with a 'ceramic' film, then the sabot/ball combination will, if performing as theorized, accelerate quicker and at the same time provide less back pressure to ensure faster ignition of the smokeless powder.

With your PT graph, you should see a shift in the point of peak pressure if you alter any aspect of the load (sabot/bullet) or the condition of the barrel; dirty or hot or lubricated etc.

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Mike Pal

As to the first part of your post with theorizing creating less pressure will produce a faster ignition or burn of smokeless powder, if anything it is the opposite.

Smokeless powder has to be heated to its flash point before it can ignite. By compressing the powder reducing space between granules the thermal energy is now focused in a smaller area instead of being dispersed around the grains or migrating into volumetric space in the bore. If the pressure from the primer carrying the thermal energy should say move the bullet/sabot before the powder has a good starting ignition then you are reducing the overall efficiency of the powder burn. In some cases it may not ignite especially if you using a slower powder.

When the powder ignites in a CF cartridge and begins to burn producing some pressure the bullet moves to contact the lands. By momentarily stopping here it allows the burn to accelerate developing pressure even faster before the bullet is forced into the bore. I think of this as the jump point of a powder burn when the bullet moves into the bore. This is one of the reasons I’m looking at duplex loads.

As to the second part of your post the answer is yes if you alter any aspect of the load.
For other conditions such as dirty, hot or lubricated bore conditions if it is severe enough to alter the resulting pressure then yes you will see it.


Ed

Quote:

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Originally Posted by MikePal

and at the same time provide less back pressure that helps to ensure faster ignition of the smokeless powder.

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Quote:

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Originally Posted by ET1

Mike Pal

As to the first part of your post with theorizing creating less pressure will produce a faster ignition or burn of smokeless powder, if anything it is the opposite.

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Yea, sorry Ed... that was a typing error...it should that said "that helps to ensure' ......it wasn't long ago in one of your other threads that I learned that smokeless powder requires pressure placed on it for better ignition. That's why I postulated that if there is less inertia on the load there would be less pressure and therefor a shift in the ignition timing.

Any idea, in terms of measured trajectory, how much a 5% increase of velocity would have on a 250 gr bullet traveling at 2000+ft/sec at 500 yds ?

Mike

Using the following parameters for my ballistics program say BC of .18 (250SST) with 100yd zero at 500yds:
2000fps would produce a drop of minus 204.85”
2100fps would produce a drop of minus 189.08”

Just for fun I do have info on a duplex load that would generate 2600fps with a 250SST and only increase the peak pressure by about 1500PSI. Given the above parameters a drop of only minus 124.56” should be seen.


Ed

RISE represents how fast pressure builds to its peak. This involves the powder’s burn rate, bullet load mass &load resistance and bore size (volumetric spacing). RISE mostly indicates a powders burn rate by its response to burn acceleration. To basically simplify this you have to understand that pressure accelerates a powder’s burn characteristics. The more pressure it is exposed to the faster the powder burns.

For muzzle loading with a sabot RISE can make a difference whether a sabot survives or shreds quicker. That marvelous piece of plastic has to deal with the oncoming pressure at a fast rate to begin with. Its ability to survive and do its job without failing IMO is also directly related to how quick the RISE is. If a faster introduction of pressure is applied to the sabot the more stress it has to endure.
RISE is assigned a numerical value where the higher the number the slower the RISE rate and the lower the number the faster the RISE rate.

A good RISE number here for sabot loads IMO would be 100 to 130.


Ed

As a continuation with interpreting PT’S I have an earlier and popular duplex PT where a recommended powder was used to ignite a slower burning powder. Here you can examine the Rise Time and Area.
Even though this actual duplex wasn’t tested till 2013 it has been used for a while. The gain in velocity over a recommended load here is 300fps with peak pressure still well under 40K psi. The one thing I can’t verify off hand is whether the old or new 4759 was used.

Attachment 28599


Now on another thread I see a scare tactic of trying to use something mentioned that was intended for CF cartridge reloading and tossing it into the muzzle loading category.
Here I’m going to simply state and ask if you have any doubts about duplex loads of smokeless powder in a muzzle loader then do not venture there. I for one have no doubts and with my equipment can monitor what is happening in the bore. With a proper approach loads can be tailored to accommodate different bullet weights and additional velocity if desired instead of being limited without exceeding a safe margin for peak pressure. When I find some good safe combinations I will share them. Also I’ll break down why they appeal to me and any benefits I feel they will provide.

Ed

Quote:

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Now on another thread I see a scare tactic of trying to use something mentioned that was intended for CF cartridge reloading and tossing it into the muzzle loading category.

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The subject was/is "duplex loads using smokeless powder " which is used in muzzle loaders also .

Quote:

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Originally Posted by jaycee

The subject was/is "duplex loads using smokeless powder " which is used in muzzle loaders also .

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Jaycee

Boy you are just looking for an argument even if you have to cross-over to another thread.

You take an article out of a reloading manual dealing with CF principles of operation and simply think you can apply them to muzzle loading to prove a point when in fact the conditions for ignition and acceleration of a powder burn are not exactly the same in both. If you understood the difference then you would know why such faster burning powders and quantities are used in smokeless muzzle loading. I suggest you do some homework before twisting statements to suit your purpose.


Ed

The 10ML-II ignition system incorporating a breech plug is an interesting design with multiple functions. Most shooters don’t give it a second thought other than it is an integral working component. Now if you take a closer look at what transpires in the BP you get a different perspective on its operation.

For the moment I need to reference what happens in CF cartridge. Here the powder basically sits on top of the primer and when the primer ignites all of its thermal energy is expelled into the powder.
With the 10-ML when a primer ignites the thermal energy is dumped into what is referred to as a flame channel and then bled off in a regulated fashion through an orifice into the powder charge. When the powder in the bore ignites pressure is built up and now the orifice regulates the returning pressure into the flame channel which now becomes a reservoir to limit the amount of pressure buildup. This is also why there are no locking lugs on the bolt because it isn’t exposed to full bore pressure.

Note: The thermal energy intensity released in a CF cartridge will never reach the powder in a 10ML-II using a breech plug.

You might ask what good is there to knowing any of this?
If you are seeking accuracy repetitive levels of ignition can play a role here. For example: when the flame channel carbons up the volumetric size is altered. By producing more pressure of thermal energy in this smaller chamber the output energy passed through the orifice is increased.
For my personal routine of BP maintenance I clean my BP after 25 fired primers and below you can see why.

Attachment 28642


To remove this carbon buildup I just use a #21 drill bit. I also address the carbon buildup on the shelf below the primer with a larger drill bit or you can use whatever tool that works for you. If you allow this carbon buildup to continue you might eventually find primers difficult to seat.

Ed

Just wanted to step back to the ignition system of the 10ML-II again as this was part of my learning curve on how it can be altered to help the burn with a slower or harder to ignite powder in colder temperatures.
Now this process does involve altering the original design of the breech plug so I’m not going recommend that anyone should just jump into this. But I do have to mention that any test results I share will be using a modified breech plug/s that I have been using now for 5-years. There will be a slight difference in the test results compared to using a standard BP. My peak pressure will be slightly higher and a small gain of velocity will be seen.

Two major considerations before even considering any modification or moving outside the manufacturer’s recommendation is as follows.
What are the risks involved?
What beneficial gain can I expect?
The biggest obstacle some people have knowing what RECOMMENDATION represents that does not mean SET IN STONE or is an ABSOLUTE.
But to move safely out side of recommendations you also have to have some reasonable amount of understanding of operational principles you are now altering.

Okay now back to the BP mod and why some chose this route. The idea here was how to increase the thermal energy delivered to the powder.
By recessing the vent liner in the BP the flame channel (volumetric spacing) is reduced creating a higher pressure and amount of thermal energy delivered to the powder. This also created less exposure to heat loss from the now smaller area of the walls in the flame channel.
What the recess also provided was a smaller chamber area to start the ignition of the powder charge.

Now let’s look at the risks.
We now have a wall reduction of the BP that is going to be exposed to full bore pressure.
The recess now passes the boundary behind the sealing point of the bore. Normally the recess remains above the outside threads of the BP.
There will be higher return pressure now found in the flame channel.

When you first read the possible risk factors you become very apprehensive of this working at all. Your gut should tell you to avoid going this route.
So what changed my mind about trying this also?

Not to be accused of pushing something unsafe I’m going to stop here for the moment and allow the focus on the risk factors to settle in before proceeding with this mod that I now employ.



Ed

The origin of recessing a BP did not originate from me but by a machinist and here was his initial approach. He went with a 3/8” dia. recess ¾” deep. A few others followed his lead and were happy with the results. With the recess mod being employed for about a year with no detrimental effect from it I decided to look a little deeper into this mod.
The first thing I measured was the remaining wall thickness on the BP when 3/8” dia. recess was employed. .115” doesn’t seem like a lot of metal to support such pressures we use without being expanded. But no diameter expansion was reported. Also keep in mind there is an outer wall of metal nearby that would limit any real expansion of the BP to a point for possible tearing.

For my own piece of mind I opted to use a 5/16" diameter recess that now left a wall of about .145” for additional strength. This now included reducing the dia. of the vent liner head to fit into the recess.
As for the original ¾” recess depth that seemed a little too deep for my comfort even though no primer bulging or excessive blow-back was reported. After doing some tests at different level of recess depths using 1/8” increments I found a ½” was a good depth. The reason I chose ½” because I saw no gain at 5/8” where I’m now at.


Again no blow-back or primer-bulging but an increase of 2,500PSI in a known load signifying an increase of the ignition property.

Had I just taken the stance that this was a dangerous mod from my first impression and closed my mind to this option I would have lost out on a beneficial mod IMO.

Again I can’t recommend this mod because it is altering the original design. I can give/share dimensional parameters and observed results. Also to let you know why my test results may differ slightly from yours with a given load. To make this mod is a personal choice as it was presented to me. The decision is now yours to make concerning recessing a BP.

Before considering this mod you may want to try a Magnum 209 primer to see what results it produces and if you are satisfied with the results. Some shooters have reported better ignition results over the standard 209 primers in an unaltered BP.


Ed

I have a question for you Ed....way back when, PR bullets developed a solution to the 209 primer for the SML. It's a hardware swap out that modifies the ignition system a Large Rifle primer.

https://www.prbullet.com/s-kit.htm

Is there a fault with that concept, have you ever had a chance to see how it affects the pressure curves ?

I bought their Vari Flame kit a long time back (before they were making ML specific 209 primers) and found it made a world of difference to my grouping and had a far cleaner gun with no blow backs. The concept was brilliant.

https://www.prbullet.com/vf.htm

Would it not make sense to move away from a shotgun primer to a rifle primer if your using smokeless and looking for better ignition ?

The problem with the 209 primers is that they are dirty. I just picked up the s-kit and I am just about to go down to the cave to tinker! I will post some pics of everything. I just hand lapped my barrel and I'm going to get everything reassembled. I plan on using magnum lr primers.

Mike Pal

No I have not used PR’s LRVF system nor have I considered it in SML application. I can say some members on another SML board where not happy when they tried it with their 10ML-II. Currently most SML shooters on another board have opted to remain with the 209 primer even in other calibers now appearing.
I have no knowledge how it would work with black powder application.

First off I have no current sticky 209 primer issue to begin with. When my 10ML-II was new at first I had a few that would stick and require a second strike from the firing pin to loosen them. It wasn’t long before any sticking just stopped.
I agree most of the carbon issue in the BP of the 10ML-II originates from the 209 primer and cleaning this is no issue for me after a range session firing 20-25 shots in 4-5hrs with the aid of a cooling rod.
With PR’s system using rifle primers in modules I would have to constantly de-prime and prime the modules instead of simply sliding a 209 primer onto the bolt head.
With the above mention I don’t want to drop $130 plus to possibly find out I may not like their system either. If anyone wants to go this route to try then be my guest.

Another debate ongoing is which primer produces the highest thermal energy release for powder ignition? Where this would make a difference IMO will be in freezing temperatures. What I convey has proven itself and works for me. There may be other options I’m not familiar with that may work well also but for now I will leave that to others to try and hopefully they share their results.

Ed

Quote:

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Originally Posted by rippin_355

about to go down to the cave to tinker! I will post some pics of everything.

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Thanks I'd like to get some first hand feedback.....seems the whole 209 primer is an issue with the SML and would like to hear how guys have found PR's solution.

Quote:

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Originally Posted by ET1

No I have not used PR’s LRVF system nor have I considered it in SML application.

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I'm a little surprised Ed, with all the efforts your going thru to maximize the performance of the powder your gun it's something I would have thought you would have jumped on to explore. Especially, since you have access to the tools to witness the pressure peaks and bell curve offsets that can be manipulated by the primer itself.

Those VF adapters aren't a big issue, takes just a moment to prep for a shoot, really not an issue....takes less time than it does to clean up after those dirty shotgun primers :)

Mike Pal

Why would I spend $130 plus dollars for possible better ignition when I’ve already accomplished that with a onetime modification?
And no interruption to shooting to load modules and never having to replace them for any reason.

You’d be surprised how fast I can clean a BP with a few assembled tools kept handy in a kit, chuckle.
No problem whatsoever. ;)


Attachment 28695


Ed

The 50 SML can have a good kick to her when fired. You can reduce this kick some with a recoil reducer installed, a better butt pad installed and wearing a PAST shoulder pad. But this stout recoil still affects accuracy at the range especially using synthetic stocks because of their flex property. What was found to be helpful was to place the front rest bag as close as possible to the recoil lug as comfortably as you could handle.

When shooting a kicker my shooting technique differs with the amount of firmness I apply to shoulder fit. I also try to firm up my neck muscles so that when my shoulder moves back my head follows as well. So far no scope eye, chuckle. Having a scope with longer eye relief helps in this situation.

My preferred method is allowing the fore-stock to free recoil. No contact or interference to influence its response from recoil. With my shooting stick my left hand holds the stick and does not contact the fore-stock.
This is not a set in stone method but one that works for me handling heavy recoiling SML’s or rifles.

With heavy recoiling firearms flinching can easily set in and spoil your accuracy. It’s natural for the mind to instruct the body’s reaction to protect itself. Once flinching sets in you will have a hard time breaking that habit. Been there and done that.

There are still a few variables that can affect accuracy but to address one at a time is my preferred method.


Ed

Quote:

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Originally Posted by MikePal

Thanks I'd like to get some first hand feedback.....seems the whole 209 primer is an issue with the SML and would like to hear how guys have found PR's solution.



I'm a little surprised Ed, with all the efforts your going thru to maximize the performance of the powder your gun it's something I would have thought you would have jumped on to explore. Especially, since you have access to the tools to witness the pressure peaks and bell curve offsets that can be manipulated by the primer itself.

Those VF adapters aren't a big issue, takes just a moment to prep for a shoot, really not an issue....takes less time than it does to clean up after those dirty shotgun primers :)

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The VF's look interesting to me. I sometimes wonder how far the bullet/sabot combo is pushed before charge is actually ignited with a 209.

You would think that the pressure from a magnum primer would surely be enough to push it past the initial inertia of the load and remove some pressure off your powder.

Wouldn't that affect the overall pressure, velocity and accuracy ???

Maybe the initial pressure on a sabot gas cup would seal it quicker allowing the pressures to build higher ??

I’m not going to jump directly into a hypothesis being formed but will add a variable to consider.
Load resistance can alter the final peak pressure and resulting velocity. With a given load of 250gr bullet using 43gr of 4759 in a 50cal using 10lbs and 40 lbs of load resistance the greater load resistance will produce slightly higher peak pressure and velocity.

The PT shows pressure buildup occurring under .1 mil-secs. and completes the cycle of bullet exiting the bore under 2 mil-secs.
The underlying question is how much pressure from thermal energy gets into the bore before powder ignites building its own pressure with a time frame under .1 mil-secs.?

With Cecil’s theory of bullet movement he removes the ignition factor and shows only how much pressure a primer generates for bullet movement where all pressure from primer is allowed to affect bullet movement through its own cycle. This does show the strength of the primer capabilities. Just something to keep in mind when doing your analyzes.


Ed

Not sure Ed but I received my 700 custom smokeless from PR bullet last week that utilizes a 6mm case cut down. Supposed to improve seal. Guess we will see how it works.

Big Jack

I look forward to hearing your results as I have followed others using modules or actual brass casings to house the LRP. I agree that sealing will help for an improvement of focusing more thermal energy to powder.

Here precise fit is important for that seal. I take it not any 6mm brass casing can be employed because of slight different web dimensions so your supply will probably have to come from PR bullets. Some have noted flame cutting over time so a careful watch of inside the brass and possibly the head contact on the BP should be monitored.

I look forward to reading your results especially with temp range and different powders.
Any noted wear observations would also be appreciated.
Have to ask if this is a 50 or 45 as 45’s are becoming more popular. This will be the next generation of SML IMO.

Hope your expectations are met with the new custom SML and have a lot of fun with it.


Ed

Quote:

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Originally Posted by Big Jack

Not sure Ed but I received my 700 custom smokeless from PR bullet last week that utilizes a 6mm case cut down. Supposed to improve seal. Guess we will see how it works.

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I bought an extra pac of the small rifle primer VF adapters for my 209 plugs.....I see he sells the 6 mm adapters for $2 ea (x10 for $20)....throw them in with some bullets and save a bit on the s/h :)

Because of the interest in learning more about internal ballistics this was also a prompt to get a PT unit. As mentioned it can show more than peak pressure. Some of the functions I haven’t mentioned because they would probably not be of interest to most. The one function I enjoy using is monitoring different points of the pressure curve. This is done with a moveable cursor that can move as low as .02-milliseconds.

A while back I began monitoring my experimental powder load of the new 4759 while trying to apply it to a 200gr bullet. What I did see was an erratic pressure decay that I did not yet experience. I was surprised to see where pressure instead of decaying was trying to slightly climb again and measured about 1,200PSI increase at one location.

Attachment 28750


So what does this suggest to you about this particular powder burn?


Ed

Well I’ve done enough talking about the 10ML-II and smokeless powders for now.
My choice for a duplex booster has been made and will just leave a picture of the powder for anyone to contemplate my reasoning. This powder choice should also yield a lighter single powder load with a smaller bullet.
What hasn’t been mentioned is how to tailor a duplex load and remain in safe pressure limits.
How to monitor and adjust for temp sensitivity.
Maintaining a simple log book is an asset and good practice.
No sense in getting into the above mention until I have some test samples to review in the spring.

Attachment 28771


Ed