Yes some good info there.
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Yes some good info there.
Big Jack
I limit the pressure of my loads to 40K/psi to keep a safe margin for error.
The 10ML-II barrel has a rated yield strength over 80K/psi and about 118K/psi for tensile (rupture) strength.
My goal for a 200gr bullet is more for varmint shooting as there are very few bullets in this weight category that will not seriously fragment at close range if your pushing them say at 2500fps. The 200gr XPB (all copper) will handle that velocity but trying to get an accurate load is really challenging.
My original goal was first getting the 200gr bullet up to 2500fps with respectable accuracy. Second stage then with the aid of duplexing powder was to see if the load could be safely taken to 2650-2700fps for 300yd capabilities. I know there is a rule about using multiple powders but they can be safely used if you know what you are doing and have a good understanding of internal ballistics mostly powder burn rate characteristics. I’m not promoting using a duplex but have no reservations for my application with the knowledge I now have.
2013 & 2014 have been bad years for me and hope 2015 will allow me to continue my own load developments again.
Picture below are about the 3-candidates for 200gr bullet testing. For choice of sabot/s I had to knurl them for best load resistance.
Attachment 27656Attachment 27657
And I have a selection waiting to be tested. :)
Again good luck with your endeavor
Ed
Thanks Ed
For me I am looking for a good 300 yard deer load.
i think I found a pound of 2400 and a pound of Viht N110. I already have N120 but use it in my 17fb and that stuff is impossible to find!
Duplexing is something I have been thinking about as well. There are some sources for good load data on that. What is interesting is if done correctly, pressure can be lower than with a single type charge.
If you try this please let me know your results.
Big Jack
You are absolutely right about what a duplex can do for lowering peak pressure and increasing velocity.
The key is having the right amount of booster powder (primary ignition) to generate a sufficient burn for the main slower powder charge to carry a good burn. In essence you are holding a higher trailing pressure curve (below peak pressure) that supports a higher bullet acceleration rate until the bullet reaches the muzzle.
Some individuals have been using duplex for years and swear by it.
I have been reluctant to duplex as long as my load requirements were met by a single powder. Well now that I’m coming to a road block for more velocity than what a single powder can safely provide duplexing is the next obvious step.
Even though not a true duplex I’ve read that some individuals will incorporate about 4-5grns of a faster powder to ensure ignition of the main charge in extreme cold weather.
When I can get back in the groove hopefully in 2015 I will gladly share my results.
Hey if you want to experiment with duplexing starting with a 250gr bullet you can play with these loads that are listed on another board. N110 can be substituted with 4759 for close related results.
Attachment 27661
Ed
I've always been leery of duplex loads in the MLII. Also, 4227 was mentioned as a possible powder. From experience, I can assure you 4227 can be a horrible powder in the MLII. It will not reliably ignite in cold or damp weather. That is why Savage quite recommending it.
Ok good to know thanks.
Tactical870
No disagreement about 4227 if using a standard breech plug in the 10ML-II.
In my case I now use a modified breech plug that produces a higher thermal energy output from the primer and will revisit 4227.
Also by drilling my own vents using a harder screw (Grade 12) my vent orifice starts at .032” again allowing more thermal energy transfer to the powder than a new standard supplied vent.
If Savage would have built a BP with a shorter primer flame channel to vent then they would have produced a top notch ignition system IMO.
Ed
ED
Did you take a look at PR's large rifle primer conversion kit?
I think it will completely change ignition characteristics.
I am seriously looking at this for one of my savage mz's.
If I go that route I will need to start from scratch again.
I wonder if the higher energy produced from say a magnum primer is enough to get say H322 or 4227 going....
I'm still toying with the idea of running 2400. I know some guys like it in the Savage's....