308 16” barrel suppressed shooting LT-32?

[SamT1]

so I’ve got a 16” 308 AR. so I need to work up a load for this thing. I shoot suppressed almost always.
I understand I need to burn as much powder as possible to keep this thing as quiet as possible. (Not interested in subs, just full power supers)
I have a lot of 150gr sst, 150 nos BT and 165’s in both those also.
I have a nice powder supply too, pretty much anything you can think of. But I have an unopened keg of Lt-32, I bought cheap because I guy couldn’t use it or something a long time ago. It’s the fastest powder I can find 308 data for, can barely find it for LT-32.

Is this right that I need to use super fast powder? Worth the workup with a not so well known powder? H4895 would be my stand by, but I’m game for something that Meters better if it may improve my burn and is accurate.

I’ve also seen data suggesting the closer to max the higher percentage of powder I’ll burn.

 

[Load Master]

What is your end goal?

 

[SamT1]

What is your end goal?

Moa accuracy
Hunting rounds.
Perfect cycling
No huge fireball.
All the velocity I can get from the short barrel

IF I can save some noise along the way that’s great.

 

[Load Master]

A standard load for a 308 Win is somewhere north of 2300 feet per second. Anything greater than 1126 feet per second you might as well run without the suppressor. The projectile's supersonic shockwave is your primary noise source.

 

[jmorris]

The projectile's supersonic shockwave is your primary noise source.

Not even close to correct. Shoot a 308 with regular ammunition and the report is night and day different with and without a suppressor.

Like shooting a .22lr with supersonic ammunition vs a 308 rifle, kind of difference.

 

[SamT1]

A standard load for a 308 Win is somewhere north of 2300 feet per second. Anything greater than 1126 feet per second you might as well run without the suppressor. The projectile's supersonic shockwave is your primary noise source.

My ears beg to differ on that.

Not even close to correct. Shoot a 308 with regular ammunition and the report is night and day different with and without a suppressor.

Like shooting a .22lr with supersonic ammunition vs a 308 rifle, kind of difference.

you know it’s doing good when you hear the bullet making its way through the air.
I really hate muffs myself, and don’t like disturbing others with my shooting. While you can hear the full power 308’s, they don’t carry very far.

 

[Load Master]

Someone should tell J.D. Jones all his work is for not.

 

[jmorris]

As long as he had fun his work wasn’t a waste of time. If you are referring to the 300 whisper in particular, one can load subsonic 308 Winchester that duplicates it, in power and report. The only thing is has over the 308 is that it can fit and run in an AR 15.

In any case that doesn’t seem to be what the OP is after. Would subs make less noise? Sure, no one is saying they wouldn’t. Can you diminish the report of supersonic loads significantly with a suppressor? Absolutely.

 

[Load Master]

As long as he had fun his work wasn’t a waste of time. If you are referring to the 300 whisper in particular, one can load subsonic 308 Winchester that duplicates it, in power and report. The only thing is has over the 308 is that it can fit and run in an AR 15.

In any case that doesn’t seem to be what the OP is after. Would subs make less noise? Sure, no one is saying they wouldn’t. Can you diminish the report of supersonic loads significantly with a suppressor? Absolutely.

That is a very subjective. I guess I'm not fully understanding the goal.

 

[SamT1]

Someone should tell J.D. Jones all his work is for not.

We’re talking about different purposes. I fully understand that supersonic ammo will have some sound. I shoot lots of supers from my blackouts.
I have 2 blackouts to shoot if I want silence.
I run the can on the 308 to:
1. Protect my hearing
2. Keep the public out of my business while I’m shooting hogs, coyotes, and targets. Dang city folks living in the country like to call the law when they hear shots.
3. Get more kills since it takes varmits longer to find where it’s coming from, even though they do hear it.

A suppressor on a 308 easily accomplishes that. It’s no where near like a blackout shooting subs, but if there’s any wind at all a coyote at 200 yards can’t decide how to run when you pop his buddy. Plus if your deer hunting or anything else from a stand on a lease with others it generally won’t disturb anyone else’s hunting when you take your shot.

 

[jmorris]

That is a very subjective.

Only if you haven’t shot both side by side.

A set of foam plugs can give an NNR of 29 dB a set of muffs can give an NNR of 27 dB, use both, muffs over plugged combined will give you a NNR of 34 dB.

There are a number of .30 suppressors that will give you a 30 dB sound reduction.

 

[Load Master]

Only if you haven’t shot both side by side.

Here is part of the problem. Are you evaluating sound for its level at the rifle or what is heard down range? At 100 yards the noise heard at that location will be very close in amplitude with or without the suppressor. If the intent is to change how game hears the noise a velocity difference is needed.

 

[jmorris]

Here is part of the problem. Are you evaluating sound for its level at the rifle or what is heard down range?

At the rifle (thus the use of “report” vs sound from projectile), is generally where I am at, unless I am working the pits or playing around with my remote trigger.

 

[Load Master]

At the rifle (thus the use of “report” vs sound from projectile), is generally where I am at, unless I am working the pits or playing around with my remote trigger.
.

There has to be a good story behind the "remote trigger"

 

[jmorris]

I just enjoy building things, that one was just one that went with my remote rifle setup.



Also enjoy playing around sometimes.



It does bring up another point about down range sound and firearms. A projectile traveling faster than the speed of sound won’t spook the animal until after he had been hit with said projectile and the sound of the impact with the animal can be quite loud itself.

Not unlike this where you don’t hear anything but the switch until the bullet is already made impact.

 

[jmorris]

Sorry about the derail there Sam,to your original question. If sound is of little concern I give it little consideration, instead working up a load like any other time and report “is what it is”.

 

[SamT1]

Sorry about the derail there Sam,to your original question. If sound is of little concern I give it little consideration, instead working up a load like any other time and report “is what it is”.

I loaded a ladder with the LT-32
36, 37, 38, 39, 39.5 grains. Under a 150 sst. Will see where that takes me. Using those numbers from accurates data for a Berger 155. I seared the bullet to the canalure and put a mild crimp on them. Cci primer and LC brass.

I was very impressed with how the powder metered compared to my usual 4895. I started the process trickling them in, but the last couple I just verified on the scale. This powder looks promising that I can load some high quality Ammo without weighing every charge. I may set up my all American with a auto drum if this works out.

 

[RecoilRob]

Looks like LT-32 is about the same as RL-7 and is about as fast as 308 should use...assuming the gun will run with it. Having the can 'should' help deliver enough gas to cycle, but without it the port pressure might not be enough but you'll not know until you try I guess. I've used RL-7 in 5.56 and it's iffy whether my AR's will run it OK or not. Should be a fun experiment!

Edit: wanted to mention the possibility of low charge density using such a fast powder and the possibility of wide velocity variation with changing positions. If it ends up working well enough, you might consider a buffer to positively position the powder back in the case as it could help with consistency.

 

[Load Master]

jmorris, very impressive setup that would be fun to play with. SamT1, like wise didn't mean to derail you thread. It is an interesting thread none the less.

 

[SamT1]

I shot em. Not ideal conditions. 5-10 crosswind gusting. Impromptu shooting range. I know I pulled a couple shots and I omitt them from my analysis. Everything I shot even with the pulls was less than 2 moa. in general they string left and right due to wind I assume.

I wasn’t sure what to expect from an AR10 I paid $650 for. But it does have a $650 scope on it! Diamondback db10 16”, vortex viper, silencer tech can (has a slight end cap strike but that’s doesn’t seem to effect anything)

I was shooting a string and then I’d adjust my scope before the next to try and zero it.
I did not bring my chrony, It’s a pain since it’s been shot a couple times it’s super finicky.

36 grains:
Worst load I shot, loudest blast. 1.5 moa (left and right, wind) brass was very close to the gun, flawless function, but only the 3-5th shot after cleaning. I wouldn’t load it, brass was dirtiest, may not run a dirty gun or cold weather?
37, slightly tighter up and down, I don’t believe it would bust moa without the wind, but it’s close. Quieter. Ejects brass a reasonable distance. Brass still dirty. Primer is still very “round”
38, this was my best group, would be just under moa without wind, even the shot I pulled only opened it to 1.5 moa. Brass is cleaner. I feel like it was the quietest.
39, shot as good as the 38gr load, but started to flow a little primer around the pin strike. Brass was a little farther out. Felt recoil jumped , but still mild with the setup.
39.5gr. Group started to open back up. Significant primer flow. Recoil up, sound is up too here. Big jump in wear on the brass. It’s a safe load still but I’d conciter it a hot load.

So I’m gonna play in the 38-39 range and see where that takes me. I’m confident that’s where the accuracy node is. Funny how that works. If I was going to wing a load and not test it, it would have been in that range. I’ll revisit this with a good rest on a calmer day.

Another funny thing here, last time I used my scope it was on a 308 bolt gun, looks like I had it cranked 2 moa right for wind that day. I put it on the AR on top of a riser (3” over bore) when it was all said and done I went to readjust my zero set and it was sitting on zero elevation and windage. The elevation turet is on the 1 now though not the 2 or 3 where it was before. Looks like I’m gonna need that 20 moa mount.

 

[Walkalong]

So I’m gonna play in the 38-39 range and see where that takes me.

Sounds like a good plan.

Not ideal conditions. 5-10 crosswind gusting.

I did that with some .222 Mag loads at 300 yards Sat. N-133 and 8208-XBR with the 50 Gr V-Max. Shot two five shot groups each, but it was hard to pick a better performer. The 8208 was slower judging by the primers, but it was the first I had tried with 8208. The N-1333 load was worked up to some time back. Going to bump up the 8208 and try again, hopefully in less wind. The 8208 was flatter on target.

Tough to evaluate things when it is real windy.

I bought a pound of 8208 and LT-32 at the same time some years back, but have failed to do anything with the LT-32 and have just started with the 8208. Both are small kerneled stick powders that meter very well. I had really intended to try LT-32 in .222 Mag first.

I'm looking forward to your conclusions with LT-32 in .308. My main interest would be with 168s though, and I am not sure LT-32 isn't a bit quick for that. Dunno.

 

[Blue68f100]

I just enjoy building things, that one was just one that went with my remote rifle setup.



Also enjoy playing around sometimes.



It does bring up another point about down range sound and firearms. A projectile traveling faster than the speed of sound won’t spook the animal until after he had been hit with said projectile and the sound of the impact with the animal can be quite loud itself.

Not unlike this where you don’t hear anything but the switch until the bullet is already made impact.

I need one of those setup to shoot the hogs that come into my deer feeder. They hardly ever show up at a respectable time, normally 2-4am. I may have to look into building one so I don't have to get out of bed.

Nicely done

 

[Dudedog]

It’s a pain since it’s been shot a couple times it’s super finicky.

So it's a bit Persnickety after it got shot the second time?
Can't possibly understand why

 

[Walkalong]

So it's a bit Persnickety after it got shot the second time?

Mine quit being anything after the first one.

 

[SamT1]

Here you go guys. 38.5 grains LT-32
300 yards. I’m shooting low and right a bit. Looks like I need to chrono these because I dialed it up using ballistics table and I’m obviously over estimating velocity.

I happy. That was done without any dot in the center to aim at. Shot 5 I went for a headshot, but it was more of a collarbone shot since I didn’t dial up enough