- Messages
- 2,515
- Reactions
- 1,495
Hello. Been thinking about short barrels and AR15s, like the original Commando.
The history was that the 10 and 11.5" XM-177 barrels were too damn loud, so the 4.5" moderator was used to quiet them down. Later on the military shifted to simply adding that amount to the bore length to create the M4, which is much less loud than an un-moderated 11.5 or 10" barrel, yet has much more velocity.
AR15 pistol and SBRs with XM-177 barrels don't normally get moderators because the are legally silencers, so those concerned about the noise use blast cans, which are just big open ended expansion chambers that throw the muzzle blast forward. My understanding is that they are still super loud indoors.
If you're going to put a longish muzzle device on anyway (blast can, moderator style flash hider), wouldn't it be useful to have a muzzle device that simply extends the bore almost like having a 14.5" M4 barrel?
I realize that adding another section of rifled barrel would have problems, but what about having a straight section that is the inner diameter of a 5.56 silencer baffle? Something like 7mm. The point of a baffle is that it allows the least amount of gas blowby without touching the bullet, so would a 7mm tube that's 4 inches long restrict the blowby enough to boost the downrange bullet velocity while increasing velocity? Would it have a negative effect on accuracy? Does anyone make such a device?
The Retrorifle "fake moderator" on the far right is said to be "solid", and clearly tapers to a small inside diameter from the hider cuts back to the threads. How small is the bore in such devices, and do they quiet things down?
Thanks.
The history was that the 10 and 11.5" XM-177 barrels were too damn loud, so the 4.5" moderator was used to quiet them down. Later on the military shifted to simply adding that amount to the bore length to create the M4, which is much less loud than an un-moderated 11.5 or 10" barrel, yet has much more velocity.
AR15 pistol and SBRs with XM-177 barrels don't normally get moderators because the are legally silencers, so those concerned about the noise use blast cans, which are just big open ended expansion chambers that throw the muzzle blast forward. My understanding is that they are still super loud indoors.
If you're going to put a longish muzzle device on anyway (blast can, moderator style flash hider), wouldn't it be useful to have a muzzle device that simply extends the bore almost like having a 14.5" M4 barrel?
I realize that adding another section of rifled barrel would have problems, but what about having a straight section that is the inner diameter of a 5.56 silencer baffle? Something like 7mm. The point of a baffle is that it allows the least amount of gas blowby without touching the bullet, so would a 7mm tube that's 4 inches long restrict the blowby enough to boost the downrange bullet velocity while increasing velocity? Would it have a negative effect on accuracy? Does anyone make such a device?
The Retrorifle "fake moderator" on the far right is said to be "solid", and clearly tapers to a small inside diameter from the hider cuts back to the threads. How small is the bore in such devices, and do they quiet things down?
Thanks.