Reloading velocity issue: I can't figure that one out!!!

[Fox]

Sorry if I wasn't clear but my barrel is 2" shorter. I believe Jay and others were right, these 2" made a big difference in this case.
I never seen that with my 30-30 or 45-70 I assume it'sprobably because heavier bullets and faster powders are used?

800fps loss for 2" is a heck of a lot

[skypilot]

Thanks you guys!!

I really had a hard time to believe that a barrel 2” shorter in association with a light bullet and a slow powder could affect the velocity that much but now I’m pretty sure it does.

Yesterday after reading your comments I looked for a faster powder used in this reloading data that I had in stock. Sure enough I had H4895 and lots of IMR3031. So, up I went to reload 5 shells of each (36g for IMR3031 and 37g of H4895). Both chrono very close to the reloading data, around 3250fps. IMR3031 grouped alright too.

The wind died and having more time on my hand I decided to quickly load up 5 more shells of 38g of IMR3031 that I could shot over 300 yards, after all that’s why I’m working a load for. Chrono average 3312fps and group around 4.5”.

Anyway I will keep H4350 for the 100g because it groups and chrono very well but I’m going to experiment a lot more with the 70g.
It’s pretty neat to learn something!

Attachment 35340

Another suggestion to consider.....Load different weights of powder but same bullet and COAL(seating depth). Shoot them at 300m or yds in a true round robin manner t keep yourself unbiased and pick the load with the least vertical dispersion. Ignore the horizontal dispersion, it is likely wind.

Take the best(least vertical dispersion load) and narrow down the powder weight to be closer to either side of the best vertical dispersion load.
You are attempting to get the max SAFE velocity with the least vertical dispersion. That point will be or close to your low Statistical Deviation and most consistent MV.

That load will be the best load of that powder/bullet/primer/case/etc. for that rifle all the way to infinity. Just shoot those longer distances and record the drops.

Wind and other environmentals however are a whole other effect.

[Big Jack]

I had check most of these variable (scale and chrono works well), I don't crimp for my bolt action.

I reload for half a dozen 243 winchesters and you may want to give the Lee factory crimp a poke. Also seat that sucker 10 thou or so off the rifling.

Or go to the dark side and buy 87 Vmax or the other way and do 58 vmax . If you do the latter let me know I'll pull out some loads I have used that'll knock your socks off for accuracy.... those have a specific col that is nowhere near the rifling but boy do they shoot!

[Big Jack]

800fps loss for 2" is a heck of a lot

Hey Fox not with a slower burn powder. Seems like a lot I know but short barrels like certain powders....

[Big Jack]

Another suggestion to consider.....Load different weights of powder but same bullet and COAL(seating depth). Shoot them at 300m or yds in a true round robin manner t keep yourself unbiased and pick the load with the least vertical dispersion. Ignore the horizontal dispersion, it is likely wind.

Take the best(least vertical dispersion load) and narrow down the powder weight to be closer to either side of the best vertical dispersion load.
You are attempting to get the max SAFE velocity with the least vertical dispersion. That point will be or close to your low Statistical Deviation and most consistent MV.

That load will be the best load of that powder/bullet/primer/case/etc. for that rifle all the way to infinity. Just shoot those longer distances and record the drops.

Wind and other environmentals however are a whole other effect.

That right there is the ticket.

Once you do that vary your col to fine tune further if you like.

You should be able to attain 1/2 MOA at 300 yards.

[seabast]

800fps loss for 2" is a heck of a lot

It seems a lot to me too but so far all my testing go that direction (around 30 rounds fired). I'll try that load again just to be sure though.

[seabast]

Another suggestion to consider.....Load different weights of powder but same bullet and COAL(seating depth). Shoot them at 300m or yds in a true round robin manner t keep yourself unbiased and pick the load with the least vertical dispersion. Ignore the horizontal dispersion, it is likely wind.

Take the best(least vertical dispersion load) and narrow down the powder weight to be closer to either side of the best vertical dispersion load.
You are attempting to get the max SAFE velocity with the least vertical dispersion. That point will be or close to your low Statistical Deviation and most consistent MV.

That load will be the best load of that powder/bullet/primer/case/etc. for that rifle all the way to infinity. Just shoot those longer distances and record the drops.

Wind and other environmentals however are a whole other effect.

I'm on it Boss!
Thanks

[seabast]

I reload for half a dozen 243 winchesters and you may want to give the Lee factory crimp a poke. Also seat that sucker 10 thou or so off the rifling.

Or go to the dark side and buy 87 Vmax or the other way and do 58 vmax . If you do the latter let me know I'll pull out some loads I have used that'll knock your socks off for accuracy.... those have a specific col that is nowhere near the rifling but boy do they shoot!

I already have the crimper but I was thinking about using later on. I just strated reloading for the 243 so I keep my focus on finding the best powder for the Nolser 70g "for my rilfe".
Thanks

[seabast]

I reload for half a dozen 243 winchesters and you may want to give the Lee factory crimp a poke. Also seat that sucker 10 thou or so off the rifling.

Question to you Jack: Can you really crimp if there is no crimp groove? I light crimp I assume?

[seabast]

Bought so Varget last night and loaded some 38, 39, 40 and 41g. Going try them in the next few days.
That reloading becomes a part time job