Subsonic 50 cal load

[.375Mojave]

Can anyone recommend a program that can give a starting load of H1000, Retumbo or 50BMG powders that will yield approx 1050fps loads out of a 750gr 50 cal projectile in a 26" barrel?

I am considering a new project and wanted to get some idea of required case capacity and don't know where to start.


Thanks,

 

[The Mechanic]

Re: Subsonic 50 cal load

And he is here on the hide.

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[The Mechanic]

Re: Subsonic 50 cal load

Forgot to add. Those slow burning powders will detonate when undercharged to that extent.

 

[.375Mojave]

Re: Subsonic 50 cal load

You are assuming a partially filled case regarding detonation. That would obviously be a dangerous load.

I am talking about a shortened 408 CT case with a 95%+ case capacity.

Just trying to get a handle on just what that charge might be as a starting point.

Thanks,

 

[bohem]

Re: Subsonic 50 cal load

QuickLoad can do some of that but it doesn't account for SEE.

If you keep the loads over about 70% fill with those powders you'll be OK to go with QuickLoad.

I tried to underload my 7/300WSM to be a reduced recoil load with H4831sc and stopped at a 60% case fill. They had a delayed ignition (clickBANG) issue and I fired 2.

 

[The Mechanic]

Re: Subsonic 50 cal load

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: .375Mojave</div><div class="ubbcode-body">You are assuming a partially filled case regarding detonation. That would obviously be a dangerous load.

I am talking about a shortened 408 CT case with a 95%+ case capacity.

Just trying to get a handle on just what that charge might be as a starting point.

Thanks,</div></div>
I thought you were talking about a .50 with a 750 grain?

 

[.375Mojave]

Re: Subsonic 50 cal load

I did not explain very well so here goes.

I am thinking about taking a 408 Chey Tac case, neck it up to 50 cal for a 750gr bullet and shortening the case down to the appropriate size to be a 95% capacity charge of sufficient powder to keep the bullet subsonic.

I am open to suggestion on powder type but even at these low velocities I assume a slow buring powder is still preferred to prevent pressure issues. I keep lots of H100 and Retumbo around for my 338 LM so it seemed a logical starting point.

I have been thinking about tinkering with a suppressed 50 cal. My reasoning is that in order to have enough energy (wgt X Vel = energy) to be useful, the obvious offset of low velocity is weight. The additional benefit is the BC of a 750gr 50 cal is hard to beat so it will carry velocity better.

Not sure what the practical application would be beyond urban sniping, but I have a rifle in the CT chambering and thought about getting dave Kiff to make me some reamers and rebarrel the gun to experiment a bit.

 

[The Mechanic]

Re: Subsonic 50 cal load

So you want to make the .500 (.510) Whisper.

 

[LARMIKE]

Re: Subsonic 50 cal load

If you use a 50bmg case you can get some of the binary steel epoxy and fill the case up just below the neck.Put a fired primer in backwards to hole the goo in. Let them dry for a day or two, be careful as they will get hot. Use a lathe or drill press with a 1/2 in drill bit to drill out the center. You now have a reduced capacity case for your .50 you may have to use a long punch to deprime them. I used about 80-90 grs. of 5010 worked just fine. you can just neck size them so they last longer as it seems like the full length sizing cracked the epoxy. I had a AMAC 5100 with a suppressor. I custom made some 800 gr. bullets. You could hear them fly thru the air. It worked for me, Your on your own. Mike

 

[Greg Langelius *]

Re: Subsonic 50 cal load

I think this is more like going after a mosquito with a sledgehammer. The case I would suggest would be the .50AE. The powder I would suggest would be something more like Unique or Trail Boss.

 

[.375Mojave]

Re: Subsonic 50 cal load

Thanks to all for the input. I have a Lawton action in a McRees chassis with a Nightforce scope that I have played with that is currently chambered in 375 CT Improved of my own case design (using necked down/fire formed 408 CT brass).

My 338 LM more or less fills my long range bill at this point and is a lot better as an elk hunting rifle so I am thinking about this as one possible re-use of the weapon. This is why I am interested in using the CT brass since it is an easy re-size on the neck and I have a boltface that works with the brass.

I use Unique for light loads in my 44 Mag so I am familiar. What is the thought on this fast burner over slow for a suppressed weapon? I saw some info on a subsonic 50 using Red Dot so obviously there seems to be logic in fast burning powder in a suppressed weapon. I assume you want all gas expansion over and done with before the bullet exits and I guess it allows for a shorter tube/longer suppressor, but I would like to hear your opinion there as well.

Again, I really appreciate the input.

 

[.375Mojave]

Re: Subsonic 50 cal load

One last note, I see reference to a 960 grain bullet and would like to base the round and twist rate on the bullet to net out max energy.

I have not located a source of the 960 gr bullets I have seen referenced so any input there would also be appreciated.

 

[.375Mojave]

Re: Subsonic 50 cal load

I am bumping this to the front in case anyone has info on the 960 gr 50 cal projo.

Thanks,

 

[bohem]

Re: Subsonic 50 cal load

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: .375Mojave</div><div class="ubbcode-body">I am bumping this to the front in case anyone has info on the 960 gr 50 cal projo.

Thanks, </div></div>

The 950gr pill that I have some samples of came out of a cast lead mould that my dad bought from NEI many years ago. It is a gas check, flat base, mild spire point design that goes 950-960gr when gas check and lube are applied.

They're pretty cheap to make compared to shooting 750 Amax's and consistent MV's are much easier than with jacketed bullets due, I <span style="font-style: italic">THINK</span> from the inherently low engraving pressures and lubed condition of cast lead bullets.

 

[.375Mojave]

Re: Subsonic 50 cal load

Thanks Bohem.

I did not consider a cast bullet but given the low velocities intended it actually makes a lot of sense. It would not be that tough to get a mold made if none were available commercially.

I can think of some practical uses for a suppressed rifle that has hunting levels of energy and the only logical solution seems to be increased mass of the projectile.

I appreciate the feedback.

 

[.375Mojave]

Re: Subsonic 50 cal load

On further consideration the limiting nfactor may be twist rate. In order to stabilize this bullet it seems a fairly fast twist rate would be required and I am not sure a castable bullet will not strip the rifling.

Any opinions there?