Building a 9mm AR w/16" barrel - Bullet Velocity Question

[MoneyWaster]

I'm thinking about building a 9mm AR for my fiancé, (and for me of course lol), and I' m thinking about the possibility of a loss in muzzle velocity when shooting a pistol round through a 16" barrel. Does anyone here have experience with a 16" barrel shooting 9mm ammo? If so, was there a loss in muzzle velocity compared to a pistol?

Thanks in advance.

Lou

 

[Ggmac]

Increase , not decrease . Even a 22 lr see an increase

 

[Drop Port]

A 16" 9mm is a great plinker, and with some +P+ they come alive. Love the old Colt SMG! not a lot of ass but fun to shoot.
http://www.ballisticsbytheinch.com/9luger.html

 

[Lone Hunter]

I'm thinking about building a 9mm AR for my fiancé, (and for me of course lol), and I' m thinking about the possibility of a loss in muzzle velocity when shooting a pistol round through a 16" barrel. Does anyone here have experience with a 16" barrel shooting 9mm ammo? If so, was there a loss in muzzle velocity compared to a pistol?

Thanks in advance.

Lou

I'm thinking about building a 9mm AR for my fiancé, (and for me of course lol), and I' m thinking about the possibility of a loss in muzzle velocity when shooting a pistol round through a 16" barrel. Does anyone here have experience with a 16" barrel shooting 9mm ammo? If so, was there a loss in muzzle velocity compared to a pistol?

Thanks in advance.

Lou

I have a Colt 6951 9 mm. It is fun to shoot. One thing that will surprise you is the recoil. The bolt is the recoil and there is a difference between a 5.56 and the 9 mm. It is not hardly noticeable but more than a 556. That's the only way I can describe it. Certainly not unbearable. It is a lot of fun and very accurate. Haven't run it through the chronograph but you can tell there is more velocity when you hit the steel targets.

 

[MoneyWaster]

I have a Colt 6951 9 mm. It is fun to shoot. One thing that will surprise you is the recoil. The bolt is the recoil and there is a difference between a 5.56 and the 9 mm. It is not hardly noticeable but more than a 556. That's the only way I can describe it. Certainly not unbearable. It is a lot of fun and very accurate. Haven't run it through the chronograph but you can tell there is more velocity when you hit the steel targets.

I actually have an AR "pistol" in 9mm (10" barrel), and I agree with you, the recoil is surprising. The one that I have is actually really accurate. Shooting supported, it will make one ragged 1.25" hole at 25 yards with a red dot. I'm thinking that the 16" barrel and a real scope would make a great plinker. At $0.18/round, its the most economical round to shoot outside of a .22 RF.

 

[MoneyWaster]

Increase , not decrease . Even a 22 lr see an increase

I just wasn't sure considering how fast pistol powders are. I was assuming that the powder charge was optimized for something like a 4" - 5" barrel. If velocity increases going to 16", then it is a win/win.

 

[Milo 2.0]

I just wasn't sure considering how fast pistol powders are. I was assuming that the powder charge was optimized for something like a 4" - 5" barrel. If velocity increases going to 16", then it is a win/win.

A lot of people go 14.5 and then pin a compensator or flash device on the end. Need ear pro anyway.
There was talk of recoil, most 9mm carbines are blowback, it's not they recoil more, it's a different impulse. With muzzle pressures under 1K by quite a bit, it's not recoil. There are some neat strides being made to all but eliminate dot bounce, bolt groups, buffer systems.
Sig Sauer makes a gas operated 9mm system, with the piston right off the chamber and it reduces recoil quite a bit.
Ammo selection of coarse the biggest player in controlling follow up shots. For me downloaded 124gr has worked the best.

 

[alinwa]

With muzzle pressures under 1K by quite a bit, it's not recoil.

"Muzzle pressure" has absolutely NOTHING to do with recoil no matter what the innernet hacks belch out there.....



jus' sayin'

 

[Milo 2.0]

"Muzzle pressure" has absolutely NOTHING to do with recoil no matter what the innernet hacks belch out there.....



jus' sayin'

Well it does coincide with muzzle hop or rise, which can be construed as a form of recoil.

 

[MoneyWaster]

After spending the last several years trying to shoot precision, I think I'll love having a nice light 9mm AR plinker for fun. Going to the range week after week and not meeting precision expectations can get a little frustrating after a while. Sometimes you need a break. I figure a nice 4" plate at 50 yards should provide ample entertainment.

 

[MoneyWaster]

Heck, I am still entertained shooting soda cans off of my parent's back porch with my old BB gun when I go home to visit.

 

[alinwa]

With muzzle pressures under 1K by quite a bit, it's not recoil.

"Muzzle pressure" has absolutely NOTHING to do with recoil no matter what the innernet hacks belch out there.....



jus' sayin'

Well it does coincide with muzzle hop or rise, which can be construed as a form of recoil.

"coincide with" yes, connected in any way? No

"Simply put, muzzle pressure and blast are just GONE, there is no "effect"..... Anything past the muzzle is unattached, the effect (recoil) was caused by acceleration of the ejecta.


period.

Unless you hang a device outside the muzzle, tied to the rocket and CATCH some of it......

then you can use it to pull some of the recoil off.

As dumb as this sounds, you can prove . that the ejecta is effectless. Next time you let go of the shower extension hose and it whips about the shower stall, notice that you've been observing RECOIL....

So set the nozzle on the rail and let it stabilize, now put your hand up close and see if you can "push" the water stream to move the shower head. This idea of "jet pushing on the air effect" is so widely held that back in the early stages of rocketry all the rednecks in the WORLD set around discussing whether or not a rocket could work in space.

 

[Lone Hunter]

I took my friend and his wife to the range to shoot. I let her shoot my 9MM AR-15 and she liked it so much that I thought that she was going to use up all 200 rounds of my ammo. She only weighs about 100lbs, so recoil wasn't a problem for her.
Darryll

I'm not saying recoil is unpleasant or tough. I'm saying it is surprising. It is harder than a 5.56 but certainly not unpleasant. The bolt movement has a lot to do with this. The bolt group is real heavy but the weapon is very accurate. It is a very fun weapon too. One of my favorites.

 

[kzin]

http://www.ballisticsbytheinch.com/9luger.html

16" is always faster than 4" but for some rounds the maximum muzzle velocity is at less than 16"

 

[MoneyWaster]

I'm not saying recoil is unpleasant or tough. I'm saying it is surprising. It is harder than a 5.56 but certainly not unpleasant. The bolt movement has a lot to do with this. The bolt group is real heavy but the weapon is very accurate. It is a very fun weapon too. One of my favorites.

I agree with that completely.

 

[GotRDid]

I, too, have a Colt 9MM NATO Carbine from the late 80’s/early 90s era when our Dept authorized Patrol Rifles. She wears a Trijicon Reflex II in a cantilever mount.
I put a Smith Enterprises muzzle brake on her and recoil is now linear, but that heavy blowback bolt is still “bouncing” the rifle a bit.
With the advent of Pistol Caliber Carbine (PCC) matches really taking off in participation, I suggest looking into the designs available for this game. A Shooting Buddy in So. IN has a 9MM PCC Rifle with a 5” bbl and a permanently affixed aluminum shroud that makes legal Carbine length, uses Glock mags, and a Vortex red dot sight. Super light weight and accurate to boot. Likewise, he has experimented with various buffer/spring options for optimal performance/cycling. An absolute joy to shoot and about as much perceived recoil as a 10-22.
Will update with links when he replies to text, but you can check YouTube for guys like Jerry Miculek for PCC shooting.
I will be building one soon.
GotRDid.

 

[Ggmac]

I've got an old iver Johnson m-1 carbine in 9 mm , gas operated , uses old smith an Wesson 59 mags . Awesome carbine . I wish they still made it .

 

[dellet]

"Muzzle pressure" has absolutely NOTHING to do with recoil no matter what the innernet hacks belch out there.....



jus' sayin'

So then what is the term or definition applied to the thrust produced by the gasses exiting the barrel?

There is a force generated at the point the bullet leaves the barrel, releasing the compressed gasses. The amount of that force is determined my the weight, volume and speed of the gas on exit. The amount of pressure the gas is under will partly determine the volume.

Why is that thrust created not included under the term recoil, since it applies force to the shooter?

How does muzzle pressure, not have anything to do with that?

 

[kzin]

The force is generated as the gas mass accelerates away from the chamber down the barrel.
It STOPS generating recoil force on the gun at the muzzle.

 

[alinwa]

The force is generated as the gas mass accelerates away from the chamber down the barrel.
It STOPS generating recoil force on the gun at the muzzle.

Bingo