Patrol Rifle Legal Question

[Switchback]

...I don't know of anyone that carries or would use hearing protection when you deploy a rifle in a patrol setting....

Peltors are outstanding hearing protection and you can actually hear better with them on.

I am told that a well built suppressor will actually increase muzzle velocity and that is certainly a benefit with a short barreled AR.

I would question your source very thoroughly on this one. I find it EXTREMELY hard to believe. If you are lucky, you will not lose substantial velocity with a decent can. We started deploying them on our bolt guns a few years back on SOG (well, quick release). We were very pleasantly surprised to find that they did not affect our points of impact in the lease. We T&Eed several others and they all changed POI to some degree (which in and of itself is not a real issue IF it is consistent AND you document it).

I think the real benefit in having cans on your rifles (assuming it is team/department/agency wide) is that when you hear a gunshot, you know that it is NOT friendly fire.

[MountainMan]

Peltors are great for the range. But noone carries hearing protection when deploying a rifle in a patrol setting.

The info on suppressors is specific to the AR platform and not every suppressor will increase MV. It has been fairly well documented by others that are more in the know than I am. Individually tested with quality chronographs. POI is still affected though.

I couldn't tell you which brands or models will do what. My memory isn't that good. When I get mine finished I will have to see for myself. I was sceptical when I was told about the increase but I trust the source. Not mall ninja's and they weren't trying to sell me anything.

I can say without a doubt I would not want to be around when shooting and 10 inch Ar in a closed are without a suppressor. I have a 7 inch barrell that is nasty to be near with hearing protection. Shooting it isn't a big deal. I should get a pig or a levang to throw the sound forward.

[Switchback]

I carry a 6.5" AR everyday, so I am intimately familiar with the roar that that thing can put out. Hell, I don't care for shooting it under the covered portion of our range. LOL

If you come up with any specifics on a can actually increasing velocity, point me in the right direction. I can't even think of any physics that would accomplish it, to be honest. I'd like to check it out... particularly for the short-barreled weapons.

[kels]

SBRs are now legal for everyone (non felons) in Kansas.
So if I wanted to buy one and do the paperwork,
all I would have to do is get the boss to sign off on using it.

If that is not an option, there are several rifles out there with
legal length barrels and side folding stocks.
Also some the new piston ar15s come with side fold stocks.
HK91s and 93 and some of the clones can be fitted with collapseable
stocks also. However do your research before you buy.

The bull pup design is another option.
The MSR and Styer AUG are good examples of that.
The Bushmaster bullpups has some issues.
(you might check the M17 forum on Yahoo for specifics.

There are also ar15 pistols and ak47 pistols.
Again, do your research before you buy.
Some of them have issues.

[MountainMan]

I carry a 6.5" AR everyday, so I am intimately familiar with the roar that that thing can put out. Hell, I don't care for shooting it under the covered portion of our range. LOL

If you come up with any specifics on a can actually increasing velocity, point me in the right direction. I can't even think of any physics that would accomplish it, to be honest. I'd like to check it out... particularly for the short-barreled weapons.

I have a PDF hiding on one of my computers with the info if i can find it. I was going to put a can on my 7 incher and was talked out of it. Decided the 10 inch and we got into a ballistics discussion and thats when the info came out about MV. The difference isn't incredible but still surprising. I initially thought is was acting like a longer barrell and they said it was something to do with the way the suppressor was built. I don't know its not my specialty. I doubt it would have the same effect on a longer barrell. 7 and 10's aren't the most effecient in 223.

[Switchback]

I know what you are saying about the shorties. However, with that said, I remember being pleasantly surprised with the performance of ours. I fully expected greater losses in MV. I will have to look it up at the office, but our were not as bad as expected when we chronoed them. Our are really targeted as CQB platforms anyways. Otherwise, I would have kept my 16".

[Joeyd6]

My .357 +P is a HELL of a lot louder than a 5.56/.223. And cops get in shootings EVERY day with guns, some indoors. Nobody ends up with issues when that day comes. Part of the physical resposne includes auditory exclusion and most come out just fine with their hearing. A can to "save your hearing" is a waste of money since 99.9% of your shots will be practice with hearing available. A can for operational/tactical reasons is a whole different game.

[MountainMan]

A 357 is louder than a 223 in a standard barrel. Its a whole different ballgame when you are running a short barrel. I was letting someone shoot my 7 inch ar and it was uncomfortable to stand next to them and I could feel the concusion in my chest.

I have been a range officer for 12 years. I have been involved in shootings and hunted without ear protection. There is no way I want to be around someone shooting an SBR in an enclosed space without hearing protection.

My ears rang for days when I shot a bear with a 12 guage in between two buildings that were about 4 feet apart. I am not sure which would hurt worse that or the SBR. I have also shot a 45/70 with a ported 18 inch barrel, multiple times without hearing protection while hunting hogs and never noticed it.

The thing about the can is it save your hearing right then. You don't have the issues immediately. Now is it neccesary. No. But it sure as heck is nice.

As for permanent hearing loss. I have some already. I am not interested it it getting any worse.

[Switchback]

It is my understanding that hunting and LE shootings are 2 different beasts when we are talking about the physiological responses that the body goes through. Many of those responses, such as auditory occlusion, are diminished (if present at all) in sporting situations vs. law enforcement shootings.

[MountainMan]

They are completely different beasts. The bear was on duty and him or me deal. I used poor tactics against a 300lb P.O'ed bear. Hunting is much easier. No problems. But then again its outside with nothing the bounce back or hold the pressure.

Of the duty related shootings those outdoors I never noticed a thing. Indoors well I don't know if it was the adrenaline dump or the blast but I couldn't hear jack squat. Maybe it was a combination of both. But shooting indoors is bad juju. Thats why we wear double ear protection in shoot houses. Or it could be that I am delicate.

[MikeG]

I carry a 6.5" AR everyday, so I am intimately familiar with the roar that that thing can put out. Hell, I don't care for shooting it under the covered portion of our range. LOL

If you come up with any specifics on a can actually increasing velocity, point me in the right direction. I can't even think of any physics that would accomplish it, to be honest. I'd like to check it out... particularly for the short-barreled weapons.

As a thought experiment without any background in suppressors, I would think it's possible that a can improves ballistics over free air. But probably not increasing velocity relative to the muzzle. It's not a barrel.

I would think, to a first order, the can should have a larger pressure on the rear of the round than the front. That would create force that is not present in free air. That would be an improvement over free air. The metric you would want to look at is velocity at a fix distance from the breech, not the MV at the end of the suppressor vs. the MV at the end of the barrel. The round may slow down in the can, but it doesn't slow down as much as the same distance in free air.

To second and third orders, I would think you would have to account for the geometry inside the suppressor and length to see if the bow wave pressure resistance in the confined can exceeded the benefit of the positive pressure in the rear of the round. I wouldn't be surprised if supersonic rounds and subsonic rounds are opposite. I could also see the same suppressor being better than free air for some rounds and worse than free air for others. Temperature would also be a third order affect as it affects air resistance and pressure. Another effect could be turbulent vs. laminar flow if that's even an issue at those velocities. Also, wouldn't the length of the barrel have an effect? A 6.5" barrel should have a higher pressure at the muzzle than a 16" barrel since the barrel volume is about a third of the size (that's why it's louder, right?). I would think the same suppressor on a short barrel could have much different effect on velocity characteristics than on a longer barrel. Even to the point where one is an enhancement and the other is a detriment, possibly.

Isn't same true for barrels? If I gave you a 45" barrel and 16" barrel and asked which barrel had the highest velocity at 10 feet from the breech, it would depend on the round being fired, calibre, powder burn rate, bullet tip, etc, etc. correct?

Don't take any of this as if I know anything about them. I'm just thinking out loud for discussion purposes. I think it would be hard to just say "It makes it better" or "it makes it worse" without real world tests. It would definitely be interesting to take a suppressor and chrono the 6" barrel at 10 ft from the breach w/ and w/o suppressor. Then chrono a 20" barrel at 10 ft from the breach w/ and w/o the same suppressor and compare. Then change the round with various bullet weights and velocites.

[MikeG]

It is my understanding that hunting and LE shootings are 2 different beasts....

yes, one beast has four legs and the other has two. Duh.

[MikeG]

Update: I got to shoot two Colt AR-15 LE models (though not sure of the exact model, they weren't the piston ones)

Both had EOTech sights. One was 11.5" SBR and the other was 16". 11.5" was noticeably louder but I didn't think the barrel length was significant to me. Officer who had it did though.

As an aside, the encounter was by accident as an officer and I went to the nearest range because their semi-annual qual is coming up. Range was down for A/C repair and two other officers were also there. All four of us then went to a police range that was outdoors but unattended. Those two officers had rifles (SWAT guy had SBR but both were department issued rifles and sights. No suppressors.) Learned that for the officer I went with, the semi-annual qual for rifles was offset from the pistol quals which means they have to shoot quals every three months. That was big turnoff for them in terms of commitment :(. Also they were left-eye dominant but right hand shooter so it was hard to sight the rifle. (I am left-eye dominant but shoot rifles left handed so not an issue except the rounds like to eject into my face.). Rifle quals also require a perfect score which was a concern as well but the officers with rifles didn't think it was that difficult.

They swore by the EOTech sights.

Also shot the Glock 35 which the SWAT guy used for patrol. I liked that better than Glock 22.

[Switchback]

EoTech's ROCK!

...and the she shorties always get louder. You should hear my little 6.5"er!