Reduced Capacity Brass

[Fastshooter03]

I'm sure others will chime in but what is the twist rate on the WWII rifle?
Once you know that, you'll know your approximate max bullet weight for subsonic shooting.
I thought about CNC lathing up some 308 brass from solid a while back but since then I've gone with the 30-221 type and have been happy.
I've never heard of reduced capacity brass but I'm sure somebody more experienced knows for sure.


Nick

[michael30.06]

The twist on the WWII rifle I'm going to start with is 1 in 10 a Springfield 1903
think it's a 1933 production number. The max according to Maths is about 190gn but I have seen good results from an Enfield 303 with 265gn Hp, neat clean holes in paper at 100yds so apparently there is another factor involved other than twist imparted spin stability. LOTS to learn.

[michael30.06]

How about filling the 30.06 case with molten lead up to the shoulder then drilling out a shaft from primer to neck that has the same volume as a 221 fireball case? Would that be possible, I do not have a 221 case to measure but I'm sure the info is on the net some where.

[HUNTER2]

Liberty suppressor used to make machined, reduced cap. brass. They said it was not very cost effective. But have seen on U-TUBE of them shooting sub 308 with Trailboss. hope this helps...

[LouBoyd]

Originally Posted by michael30.06

How about filling the 30.06 case with molten lead up to the shoulder then drilling out a shaft from primer to neck that has the same volume as a 221 fireball case? Would that be possible, I do not have a 221 case to measure but I'm sure the info is on the net some where.

The volume of a 300-221 case I have (from the Quickload database) is 1.62 cm^3 (cc) which is 24.95 grains H2O. That's level with the case mouth.

I agree completly with the use of cast lead bullets for your application. Bore friction makes shooting jacketed or copper alloy solids very difficult at subsoinic velocities with a long barrel. In a bolt action you don't have to worry about fouling a gas port. Also cast lead bullets are much shorter than copper jacketed boattails of the same weight so you should be able to shoot flat base cast bullets over 200 grains with the 10" twist without stability problems.

[michael30.06]

So it's the length of the bullet that dictates how fast it needs to be spun in order to stabilize in the barrel. Now I can see where my assumption about 190gn being the heaviest bullet my 1 in 10 barrel was wrong. Thanks

[LouBoyd]

It's the combinaton of bullet diamter, length, weight, overall shape, intenal mass distribution, air density, air temperature, and bullet velocity which determine the spin rate needed for a bullet to stabiize. A computer program like McGyro can assist in determining a bulet's stability, but just shooting them is a more reliable test. It's hard to determine the internal density distribution of jacketed bullets.

Most bullets have the best stability at Mach 0.85 to 0.9 for subsoinic bullets, and at speeds above Mach 1.5 for supersonic bullets. Mach .95 to 1.1 are the least stable.

http://www.jbmballistics.com/cgi-bin/jbmdrag-5.0.cgi

[BHP]

Blaylock Gun Works used to make a reduced capacity .308 case. They were machined from brass barstock I believe and they suggested annealing the case necks each time for better life. I believe they were $5 each in quantities of 20 about 10-15 years ago. They were said to function properly in an M14 shooting subsonic loads. I doubt they are still in production.

I also remember reading that JD Jones experimented with something similar back when Rhodesia still existed. I believe he filled the cases to the neck with some sort of epoxy and drilled them out. That was said to be effective but time consuming and very tedious. I want to say that functioned through a stock FAL but I think there may have been some issues with consistency but I don't know.

If anything comes out of this I'd like to hear about it.