6.5 PRC slow powders and light bullets?

[new2mud]

I went out today with two rifles in 6.5 PRC using ADG brass, a case I picked at random was 67gr of h2o.

Temp was 52*, and 3 round average velocities at the muzzle with 123gr eldm, imr4350, 210gm primer and COAL 2.863" no pressure signs from 50-52.5gr in my rifles.

---------M18----Bergara
50gr----2720-----2812
50.5gr--2732-------**
51gr----2765------2845
51.5gr ---**-------2922
52.5----2868------2949

Nothing extraordinary in sd or groups, some were sub .5 moa but most were between .6 and .9moa at 100 yards. Not the velocities I want, both barrels are 24" and have 60 or so rounds through them so still breaking in. I'll see what I can get to when I start to see pressure signs, and maybe work up some loads with RL23.

@alaskan9974 The QL data that @IHFarmer07 ran shows that you have nearly 1.5 grains headroom to test with your IR4350, and that is with significantly reduced case capacity assumptions in the simulation.

Given the burn rate of IMR4350 I don't know why you wouldn't be able to hit 3150 fps within reasonable pressures. Do proceed safely and I would be interested to hear what you find.

Also, my PVA barrel (button rifling) kept speeding up until nearly 200 rounds, so you may have some meaningful velocity gains ahead of you.

 

[can1010]

twist rate has nothing to do in quickload. it is the bore cross section which is the number and width of lands and grooves.

 

[IHFarmer07]

twist rate has nothing to do in quickload. it is the bore cross section which is the number and width of lands and grooves.

Wouldn't that make a difference in velocity/pressure? You know, more or less restriction?
Only one way to find out lol......I will run it tonight and see the differences if any. You may be right, because I honestly don't know offhand.

 

[can1010]

Wouldn't that make a difference in velocity/pressure? You know, more or less restriction?
Only one way to find out lol......I will run it tonight and see the differences if any. You may be right, because I honestly don't know offhand.

it does these are the basic bore cross section
4 groove - .0529
5 groove - .0533
6 groove - .0537
these are basic with a .090 groove width. if you know your number and groove width I can refine it a little in quickdesign to get better numbers

 

[IHFarmer07]

it does these are the basic bore cross section
4 groove - .0529
5 groove - .0533
6 groove - .0537
these are basic with a .090 groove width. if you know your number and groove width I can refine it a little in quickdesign to get better numbers

Interesting.....yeah, I just know some stuff with QL, obviously you sir are very knowledgeable with it all. Never messed with quickdesign.

 

[65WSM]

Reloader 26 is a double base powder and it burns hot and fast. The nitroglycerine is easily ignited by the primer. H-1000 is a single base powder, gun cotton, and it takes longer to develop pressure. Particularly the slower single base powders, which are loaded with retardant, will benifit from long barrels. Retumbo responds to 28 and 30 inch barrels.

 

[new2mud]

Reloader 26 is a double base powder and it burns hot and fast. The nitroglycerine is easily ignited by the primer. H-1000 is a single base powder, gun cotton, and it takes longer to develop pressure. Particularly the slower single base powders, which are loaded with retardant, will benifit from long barrels. Retumbo responds to 28 and 30 inch barrels.

Your powder insight is greatly appreciated!

Would you expect all the powders at the top of the QL list provided here to be hot and fast burners? I had forgotten that I had heard that H1000 should provide better barrel life than R26 for the exact reason you mentioned.

 

[IHFarmer07]

I went out today with two rifles in 6.5 PRC using ADG brass, a case I picked at random was 67gr of h2o.

Temp was 52*, and 3 round average velocities at the muzzle with 123gr eldm, imr4350, 210gm primer and COAL 2.863" no pressure signs from 50-52.5gr in my rifles.

---------M18----Bergara
50gr----2720-----2812
50.5gr--2732-------**
51gr----2765------2845
51.5gr ---**-------2922
52.5----2868------2949

Nothing extraordinary in sd or groups, some were sub .5 moa but most were between .6 and .9moa at 100 yards. Not the velocities I want, both barrels are 24" and have 60 or so rounds through them so still breaking in. I'll see what I can get to when I start to see pressure signs, and maybe work up some loads with RL23.

I did forget that I set QL to 65k on all these figures, sorry.
67grain of h2o

 

[alaskan9974]

Thanks, what happens when case capacity is adjusted to 67?

 

[IHFarmer07]

@IHFarmer07 — would you humor me and rerun the 18" data using 69grain h2o capacity?

It just isn't making sense to me why R26, with nearly the same burn rate as H1000 (and slower than some of the others) would produce such runaway results even against the faster powders. I'm wondering if limited case capacity is skewing the results, and QL is having to compromise the results due to powder density.

69Grain of h2o

 

[IHFarmer07]

Thanks, what happens when case capacity is adjusted to 67?

Those are the 67 grains of H2O, it goes by usable case volume, wish i wouldve seen that sooner to add to each post so everyone knows what is what

 

[alaskan9974]

Got both rifles out again today up to 54gr, 3056 and 3005 respectively. Had my first 0sd and 1es load. Never had that happen before. Will work up more tomorrow.

 

[IHFarmer07]

Got both rifles out again today up to 54gr, 3056 and 3005 respectively. Had my first 0sd and 1es load. Never had that happen before. Will work up more tomorrow.

Great! Just take her slow and easy and good luck!

 

[new2mud]

69Grain of h2o
View attachment 206100

Thanks for taking the time to humor our curiosities. So it appears that (fairly minor) case capacity constraints really don't alter the recommended powder rankings to achieve highest velocity. And barrel length does not dictate powder selection either.

Learning a lot through this exercise.