Suppressor Question - Calling C3PO!

[JaxChris]

Check this video out... he has others up as well.

YouTube - YHM Phantom 7.62 QD suppressor on 10.5" Noveske 5.56 AR-15 (http://www.youtube.com/watch?v=FwWl7XbzIig)

Apparently using a YHM 7.62 suppressor on a 5.56 gives amazing sound suppression over the shorter 5.56 model. You can hear the difference by comparing the voices and other weapons in the background that this is suppressed far better than your standard dry suppressors.

Is this legit? The guy has a good rep on ARFCOM, but this is something that just seems too good to be true. =/

HELP?!?!?! =)

[ss1]

yeah, AAC and Gemtech both say you can use the 7.62 cans on .223 with good results even though the baffles have a larger bore, there's enough volume in the chambers to absorb significant gas. YHM cans are really heavy tho. Not a big fan of them even tho they are fairly inexpensive.

[Satan_3pc]

Wow through the camera it almost sounds like a silencer in a Hollywood movie.

[JaxChris]

So Phil, I have a theory that another reason you're not hearing as much from this suppressed SBR is the combination of a few factors (ammo not being one of them as the other videos all state he shoots 62gr Silver Bear):

1 - The barrel is using a slower twist rate (likely 1:12 or 1:9)?
2 - It probably has a switch block that is limiting the gas?
3 - The bullet is slowed enough that the short distance before it hits dirt is not allowing it to hit supersonic?
4 - The lower gas in the gas system with a M16 carrier plus weight insert and heavy buffer are preventing the crack of the bolt when the action cycles?

This is just a guess on my part of modifications he could be running to aid in keeping the weapon very quiet yet functional (still using standard pressure ammo). I was thinking that for my own SBR I may actually have a barrel cut down to 9" to retard the twist even more as shorter barrels and slower twists equal lower velocity.

I just wouldn't want to go below 8" of barrel in a 5.56 as that would force me into pistol gas system and put much more force through the gas system and prevent the ability to reduce bolt crack.

I'd really like the gas system off of the new Para Ordinance piston rifle - just the piston though, because it's very compact and specially tuned/non-adjustable. I would do without the special bolt carrier system that removes the need for a conventional buffer, even though having an AR with a folding stock is a novel idea for compact storage.

[Satan_3pc]

Not to mention there's probably a limiter on the camera's mic that is chopping off outside reverberation that would ultimately add to the total level of decibels, but that's minor.

[GT03235]

Judging by the smoke coming out the end of the can i believe he is shooting the suppressor wet! This greatly reduces noise more than normal.

[liquidsniper]

So Phil, I have a theory that another reason you're not hearing as much from this suppressed SBR is the combination of a few factors (ammo not being one of them as the other videos all state he shoots 62gr Silver Bear):

1 - The barrel is using a slower twist rate (likely 1:12 or 1:9)?
2 - It probably has a switch block that is limiting the gas?
3 - The bullet is slowed enough that the short distance before it hits dirt is not allowing it to hit supersonic?
4 - The lower gas in the gas system with a M16 carrier plus weight insert and heavy buffer are preventing the crack of the bolt when the action cycles?

This is just a guess on my part of modifications he could be running to aid in keeping the weapon very quiet yet functional (still using standard pressure ammo). I was thinking that for my own SBR I may actually have a barrel cut down to 9" to retard the twist even more as shorter barrels and slower twists equal lower velocity.

I just wouldn't want to go below 8" of barrel in a 5.56 as that would force me into pistol gas system and put much more force through the gas system and prevent the ability to reduce bolt crack.

I'd really like the gas system off of the new Para Ordinance piston rifle - just the piston though, because it's very compact and specially tuned/non-adjustable. I would do without the special bolt carrier system that removes the need for a conventional buffer, even though having an AR with a folding stock is a novel idea for compact storage.

1. I doubt he is using a slower twist rate barrel especially with 62gr ammo with his suppressor. Slower twists rates cause the bullet to not stabilize after leaving the barrel with heavier bullets which will get you a baffle strike and really ruin your day.


2. He might have a switchblock, no way to really tell though. Won't have much of a difference on suppression of the noise, probably won't even be noticeable.

3. That puppy is supersonic trust me. You can hear the supersonic crack as that sharp staccato sound at the very begining of the impulse. A bullet will be at its highest velocity at the muzzle, as drag and gravity begin to take their toll on the bullet after leaving the muzzle.

4. What do you mean crack of the bolt? You can still hear the action cycling but its so close to the supersonic crack its very hard to hear. The mic is also chopping alot of the noise off. These vids make suppressors seem alot quiter than they really are.

He is not using water either, that is a big no no in rifle suppressors. The expansion of the gases and pressure in a rifle suppressor is much higher than a pistol and you could blow your can up using water. Thats just the smoke from the burnt powder pouring out of the front. When you shoot suppressed that thick acrid smoke goes everywhere too, out of the chamber (I've gotten sprayed pretty good from shooting my rifle suppressed when its lubed up good from the debris and gas flying out of the chamber), between the lower and upper rec, and anywhere else it can go (hence gas in the face) when shooting suppressed.

Also, you probably dont want to cut your barrel any shorter than 10.5 for a few reasons
1. Your AR becomes a glorified 22 magnum with very short barrels due the amount of velocity lost.
2. You have a greater risk of baffle strikes due to the lack of stabilization from short barrels.
3. You DO NOT WANT slower twist than 1/9 because unless you want to shoot 40gr ammo you will have a very high risk of baffle strikes. 1/7 Twist is optimal.
4. Most, in fact every company I know of, will not warranty their suppressor if it is used on a barrel shorter than 10.5

[JaxChris]

Since my initial post I've done a lot more research on this, and kind of surprised to see this old thread getting attention now. lol

I checked with YHM & AAC a while ago about the "too short barrel" idea and both of them basically said that they will honor the warranty of their suppressors no matter what length barrel you use as long as you are not doing anything intentionally destructive to them (example given by AAC was using a different caliber suppressor than the caliber of the weapon in an attempt to have a "one can fits all" scenario). Gemtech & SWR were more strict in their responses. In fact Gemtech said only one model was allowed to be used on 9.5-10.5 commando's and that all others had to be 14.5" or longer barrels.

I agree with you completely on twist rate. 1/7 twist is ideal for pretty much everything since no one has been able to prove over-stabilization of the 1/7 barrels and I think it was likely a rumor/fact (keep spewing the same rumor until it becomes fact) started by companies with a large inventory stake in 1/9 barrels at the time 1/7 barrels came out.

I have thought about 9.5" with a 1/7 twist barrel. From what I've seen, there is more efficiency lost going from 16" to 14.5" than there is going from 10.5" to 7.5". I checked with ADCO (they really seem to know their stuff based on the number of reliable barrel mods they do) and they said a 10.5" 1/7 carbine barrel could be chopped to 9.5" without loss of reliability as long as the gas port is properly resized.

They also mentioned when going below 12" they suggest using a switchblock if you plan to shoot it suppressed, but they said the gas port size may need to be different than unsurpressed depending on the suppressor and switchblock used. And now that leaves me wondering if attempting to throw a piston into the mix is even worth it. I'll be picking the brains at Spike's, Stag, and YHM a lot more before the final specs for what I want are decided upon.

Guns basically have the same logic to them as car engines. If you change one variable from the optimal (OEM) configuration, then others must change to keep everything in mathematical harmony.

I will also agree with you that there is likely some type of echo cancellation or just a bad mic on that camcorder which was probably removing a noticeable portion of the muzzle report.