what is a good subsonic 338 cartridge?

[atombomb]

Im going to build a 338 rogue and want to barrel up something else using a 338LM bolt face to shoot subsonic. I have a 1/9.35 barrel and a 10-9 gain twist coming also... both 27”, what are your thoughts?

 

[dkhunt14]

I am guessing but I bet a 338 BR. Matt

 

[people]

There are only two I know of but do not work with a 338LM bolt. The first is the necked up version of the 6mmbr cases and the other is basically a 300blk neck to a striate case.

What you could is make something up but you would have to kill 338LM brass. You could have someone turn you some solid casings with the powder capacity you want. I have seen it done in 308 but nothing larger.

 

[P1ZombieKiller]

Im going to build a 338 rogue and want to barrel up something else using a 338LM bolt face to shoot subsonic. I have a 1/9.35 barrel and a 10-9 gain twist coming also... both 27”, what are your thoughts?

My thoughts are....... Why 338? Subsonic is subsonic..... If you only want to use 338 because you have the barrel, I hope they are old barrels. Why would you want to cut down a NEW (or newish) 27" barrel to gain 200 foot pounds of energy over the 300 BO (going from 500 to 700 pounds approx.). Yes, you can get more energy from a 285 grain bullet than you do from a 200 grain bullet..... but is it worth the extra fuss? There have been PLENTY of people that have already done all the work for you with the 300 blk out (if you have a 223 bolt head), or even the 308br (if you have the 308 bolt head).

I have 3 blk outs (all bolt rifles). 2 dedicated to subsonic, and 1 dedicate to super sonic (not quite finished yet, but should be any day)..... Great caliber, and now that Lapua makes the brass, a good quality and very repeatable round can be hand loaded.
FYI.... Lehigh also makes superb subsonic bullets to use on med to large animals in 300BO.

You asked my thoughts... I decided to share. Take the extra money you would have sent on brass, reamer, more expensive bullets, and put that into better glass, or just more loaded rounds.

 

[Sniper338]

338 bullets are too expensive to waste subsonic... jmo

Not much in that bolt face, its all big rounds

 

[Zero333]

338 LM bolt face is not ideal for a 338 subsonic cartridge.

338 Whisper would be my choice If I really had to have one.

 

[Ksmirk]

It sure wouldn't work with that bolt face but the 338 Specter has always been interesting to me! but I don't think a 10mm Mag case would fit your LM bolt face

 

[Spook]

510 whisper is the only SS cartidridge you'll be able to utilize your .338LM bolt face on.
They are a hoot, I've built several.
I have a 338BR (whisper) on a Howa/Manners T5 I'd consider parting with, also done a 338 Grendle that works really well on CZ527,Model 7 and AR-15.

 

[4xforfun]

Why would you want to cut down a NEW (or newish) 27" barrel to gain 200 foot pounds of energy over the 300 BO (going from 500 to 700 pounds approx.).

..because that is a 40% increase in energy.

Tod

 

[IdahoSharpshooter]

Use an RFN cast bullet around 350gr. www.accuratemolds will cut a gas-checked mold to your specs for about $120. Make it a single groove, .004" under size and just powder coat tumble them .

 

[atombomb]

great ideas, thanks... i have a 300BO already,
I do want something with a lot more energy

 

[rcparker1]

I don't have any experience with the 338 federal but I have loaded 220 gr 308 with trail boss and got acceptable results. Have read 338 federal will work also. Something with a smaller case like a br would be better no doubt if you don't mind the additional pains of a non standard case.

 

[JayHHI6818]

I have a 14 inch Thompson Centender barrel chamber in 338 Whisper. It was made by SSK Industries and is a blast to shoot. I buy Nosler
Blem 338 300 gr HP competition bullets from $25-32 per hundred! 338 Whisper is a 7 BR case necked up to .338. 7 BR case is 1.5 inches long and the bullet is 1.7 inches!
My load is HP 38 10.1 grs and the 300 gr bullet is doing 1014 fps.
I shot a IHMSA silhouette match with it last year and when the bullets hit the 200 meter ram it sounds like you hit it with a hammer.

https://en.m.wikipedia.org/wiki/.338_Whisper

 

[ImBIllT]

I would just use a .308 bolt face and use a 338 Federal. Sticking with the LM bolt face is gonna add a lot of work and effort.

As far being only 200 ft-lbs more energy than a 300BO, don't pay attention to energy. Momentum better describes a collision than energy. Momentum is M x V and energy is M x V^2. A sub-sonic .338 would hit harder and penetrate deeper than a .300 BO by a lot more than the energy numbers suggest.

 

[nakneker]

510 whisper is the only SS cartidridge you'll be able to utilize your .338LM bolt face on.
They are a hoot, I've built several.
I have a 338BR (whisper) on a Howa/Manners T5 I'd consider parting with, also done a 338 Grendle that works really well on CZ527,Model 7 and AR-15.

You should post a picture of both of those rounds, I'd like to see them.

 

[ImBIllT]

Don't look at energy, look at momentum. Momentum better describes collisions. Energy is M x V^2. Momentum is simply M x V. You'll notice that the momentum increases by even more than 40%.

 

[Boyd L.]

Im going to build a 338 rogue and want to barrel up something else using a 338LM bolt face to shoot subsonic. I have a 1/9.35 barrel and a 10-9 gain twist coming also... both 27”, what are your thoughts?

The best cartridge would be the 338 LM with 285 ELDs.....at 1700 yards.

 

[Midnightmedic]

Here's an idea, I have had good luck using Trail boss in belted magnums for reduced loads. Usually just fill up case to body shoulder junction; so seated bullet does not compress powder. Usually gives about 50-60% reduction in velocity from my prefered max match loads with the same bullets. Would have to reduce down some to get to subsonic. This powder is super bulky. Also agree to use super heavy cast leads for fun. Hard to get a heavy enough bullet in .338 to justify subsonic and retain enough external ballistics for any range. But sounds like FUN.

 

[ImBIllT]

Here's an idea, I have had good luck using Trail boss in belted magnums for reduced loads. Usually just fill up case to body shoulder junction; so seated bullet does not compress powder. Usually gives about 50-60% reduction in velocity from my prefered max match loads with the same bullets. Would have to reduce down some to get to subsonic. This powder is super bulky. Also agree to use super heavy cast leads for fun. Hard to get a heavy enough bullet in .338 to justify subsonic and retain enough external ballistics for any range. But sounds like FUN.

What caliber would you suggest for subsonic use that does retain enough external balistics?

 

[Yote Hunter]

.458 Socom with the 570 gr Lehigh controlled fracturing at 1050 fps has plenty of energy for anything in North America. Use the same 308 boldface actions too.