Subsonic 308 moderators
- Thread starter DaveNeal
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Foxyboy43
Well-Known Member
Yep. Shot lots of .308 subs with ASE Utra and T8 moderators - very little difference but T8 slightly shades it at the cost of additional weight.
Quite a strange experience at first but interesting and at short ranges can be very accurate.
If you are going to homeload you may well find that the difference between subsonic and transonic (i.e. noisy) is very little in powder terms so you may need to experiment - carefully!
Quite a strange experience at first but interesting and at short ranges can be very accurate.
If you are going to homeload you may well find that the difference between subsonic and transonic (i.e. noisy) is very little in powder terms so you may need to experiment - carefully!
What was your recipe @Foxyboy43 as might try a few with having a T8 + 308?
jthyttin
Well-Known Member
There's basically no good subsonic mods commercially available, apart from rimfire. You'd need lots of baffles, preferably K-type. Bullet clearance also plays bigger role.
If not going for "hollywood quiet", almost everything would work and best bet should be one where (in addition to lots of baffles and small clearance) the "jump" from bore to first baffle is short. The size of first chamber seems to be a toss, but I don't have enough experience to go further. Goal is to minimize "first round pop", where powder gases that are faster than bullet get extra oxygen inside of the mod.
Other choice is to fill the mod with some inert gas like nitrogen, but it's kind of cumbersome and only really works when you are only concerned about the "first first round" being quiet (and not "many first rounds" during a night). You can also run the mod "wet", either water or some grease/oil/foam but it also has drawbacks.
If not going for "hollywood quiet", almost everything would work and best bet should be one where (in addition to lots of baffles and small clearance) the "jump" from bore to first baffle is short. The size of first chamber seems to be a toss, but I don't have enough experience to go further. Goal is to minimize "first round pop", where powder gases that are faster than bullet get extra oxygen inside of the mod.
Other choice is to fill the mod with some inert gas like nitrogen, but it's kind of cumbersome and only really works when you are only concerned about the "first first round" being quiet (and not "many first rounds" during a night). You can also run the mod "wet", either water or some grease/oil/foam but it also has drawbacks.
Foxyboy43
Well-Known Member
Watched a few videos from this guy on YouTube, give a pretty good idea of what can be achieved.
In case the link doesn't work search for Controlled Recoil - NZ Hunting on YouTube
In case the link doesn't work search for Controlled Recoil - NZ Hunting on YouTube
Heym SR20
Well-Known Member
If you look at most truly silent firearms they have several bleed holes within the barrel that start bleeding off gases before the bullet leaves the rifling. Probably has a combined effect of both reducing the pressure on the bullet, but also ensures that a large volume of gas doesn’t hit the expansion chamber all at once.
jthyttin
Well-Known Member
Yes, a long barrel in itself has the same effect in smaller scale. In many applications bleed holes are used to lower the velocity of regular ammo to subsonic levels (think 9mm submachine gun or moderated 12GA) but it's suboptimal solution if real subsonic ammo is available.
Problems start when you combine larger powder space / lower fill ratio of centerfire rifle, jacketed bullets, longish barrel and bleed holes. Or even three of those. Small variations start to stack up and result larger MV variance.
Lead is much better, I do have one 22LR bolt we made into integrally moderated. It's Mauser 107 (actually made by Voere) and would shoot all std vel supersonic (presumably b/c of tight chamber and bore). Started drilling smaller holes, but eventually had to put something like 8mm hole (anyway larger than bore) quite near the chamber to get the velocity down. The barrel has full length removable shroud, and the rifle sounds like normal moderated 22LR. The factory thread is still at the muzzle and I left it visible. If you put a 22LR mod (or better yet airgun mod) there, the rifle becomes truly "hollywood quiet".
CBH Australia
Well-Known Member
If your Trailboss is the Hogdon branded stuff made by ADI in Australia how is the availability?
I don't think it's in current production. ADI pistol powders have been problematic these last couple of years in Australia
tackb
Well-Known Member
i have a stock of it , among other powders that the powers that be decided we can't have for no good reason !
Heym SR20
Well-Known Member
Peregrine have line of monolithic bullets designed to work at subsonic velocities. More details and load data - Subsonic - Peregrine Bullets
jthyttin
Well-Known Member
Monolithic bullets with drive bands do behave better re: subsonic internal ballistics. I've personally tried Lehigh, that was one of the first (if not THE first) in this business.
Problem is they won't usually stabilize in standard rifles, are costly, and terminal performance is still limited. I'd e.g. never shoot a mature boar with 30cal Lehigh (or Peregrine for that matter). Yes it might work, even in most situations, but the risk is there. Only brought this up since Peregrine has some kind of boar logo under Application on the website.
Regarding smaller game, those bullets won't magically stop after passing through the animal. I did try to make my own for 308, drilling a hole to 125gr H&N (yes the same company that makes world class airgun pellets) plated bullets. Quite simple if you have access to a lathe to make a drilling jig (only hand drill and vise or similar attachment method needed after that). I did get it to the point that only about rearmost 40gr of the bullet was exiting hare sized target (as solid piece, other smaller pieces might also exit) but it's still about the same re: ricochets as lobbing 22LR RN around. So fine for some places and not so for some others.
SP pistol bullets (=no modifications necessary) work somewhat OK for smaller case capacity, but with 308 the velocity variation is all over the place. And they have the same ricochet issue.
Problem is they won't usually stabilize in standard rifles, are costly, and terminal performance is still limited. I'd e.g. never shoot a mature boar with 30cal Lehigh (or Peregrine for that matter). Yes it might work, even in most situations, but the risk is there. Only brought this up since Peregrine has some kind of boar logo under Application on the website.
Regarding smaller game, those bullets won't magically stop after passing through the animal. I did try to make my own for 308, drilling a hole to 125gr H&N (yes the same company that makes world class airgun pellets) plated bullets. Quite simple if you have access to a lathe to make a drilling jig (only hand drill and vise or similar attachment method needed after that). I did get it to the point that only about rearmost 40gr of the bullet was exiting hare sized target (as solid piece, other smaller pieces might also exit) but it's still about the same re: ricochets as lobbing 22LR RN around. So fine for some places and not so for some others.
SP pistol bullets (=no modifications necessary) work somewhat OK for smaller case capacity, but with 308 the velocity variation is all over the place. And they have the same ricochet issue.
Not deer legal in the uk because of speed and energy rules set by uk Law. Its a dangerous game to play the tiny powder charge in a big case ( flashovers etc) can be very nasty !
If its for small game there are way better and safer options
I get the annoyance but the fact is it contains a serious carcinogen . Think instead how would you feel if say you where doing a bit of DIY and you bought and used such a thing without even knowing ? There are quite a few powders like varget etc that many of us used a lot and they did work good but it creates little problems now as the makers have replaced them with newer better stuff . There is always the option of having a play and sending stuff off for testing .
Fact is subsonic ammo in CF rifles and Shotguns is not that important to trade your health and possibly your life to use the older data and loads.
I think it is quite a good reason when there is a risk to the users heath and life
Any mod works for Subsonic loads
They don't suddenly change the laws of physics
If it has baffles and worked with supersonic loads it will work with subsonic loads
I have made subs in .222, .223, .243, .308, 300AAC, .338 and now 6.5Grendel
I never considered changing mods.....
If your bullet is tumbling within the first 10cm you are running something truly spectacular! Almost impossible. It may scratch a baffle if a very long bullet for calibre and a very tight bore moderator
To put that in context I have shot 160gr RNSP in a 6.5 Grendel and a .22 baffled DPT with 0.15mm radial clearance!
Work DOWN when loading subs
Doesn't matter how old your load data is, you want to be running from 1300-1400fps down the way until you find the sweet spot for accuracy and sound attentuation.
A round that produces 1150fps through a decent mod can be remarkably quiet and very effective.
My load development for the subsonic Grendel almost stopped at 7-8gr because it was so quiet as to not be worth chasing a true subsonic 1000-1050fps MV
The flashover/Detonation is something "people" always mention in discussions online,
No-one, not even PO Ackley himself was able to reliably replicate the alleged phenomenom of low charge detonation.
More people **** up this choosing to use inappropriate pistol powders instead of researching a sensible burn rate that matches cartridge to barrel length
the trickier ones to make subsonic are the 222/223 range with a slow twist
308 is a lot easier as it already allows for 180-220gr weight class bullets
They don't suddenly change the laws of physics
If it has baffles and worked with supersonic loads it will work with subsonic loads
I have made subs in .222, .223, .243, .308, 300AAC, .338 and now 6.5Grendel
I never considered changing mods.....
If your bullet is tumbling within the first 10cm you are running something truly spectacular! Almost impossible. It may scratch a baffle if a very long bullet for calibre and a very tight bore moderator
To put that in context I have shot 160gr RNSP in a 6.5 Grendel and a .22 baffled DPT with 0.15mm radial clearance!
Work DOWN when loading subs
Doesn't matter how old your load data is, you want to be running from 1300-1400fps down the way until you find the sweet spot for accuracy and sound attentuation.
A round that produces 1150fps through a decent mod can be remarkably quiet and very effective.
My load development for the subsonic Grendel almost stopped at 7-8gr because it was so quiet as to not be worth chasing a true subsonic 1000-1050fps MV
The flashover/Detonation is something "people" always mention in discussions online,
No-one, not even PO Ackley himself was able to reliably replicate the alleged phenomenom of low charge detonation.
More people **** up this choosing to use inappropriate pistol powders instead of researching a sensible burn rate that matches cartridge to barrel length
the trickier ones to make subsonic are the 222/223 range with a slow twist
308 is a lot easier as it already allows for 180-220gr weight class bullets
tackb
Well-Known Member
ok , how about a compromise ?
you label the 'whatever it is' contains 'xyz' thats harmful to your health and then let me decide if i want to use it?
(when i say you i am speaking generally i don't blame you personally x)
DaveNeal
Well-Known Member
what like they do with fags, and booze and crappy food - it'll never catch on.......
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