Extra heavy buffer for 9mm blowback rifle

[Barry54]

Attachment 328572

All the off the shelf 9mm buffers are Carbine length. I’m using a full length rifle buffer tube and A2 stock. I got an aluminum spacer made to go in the rear of the tube and it works well. The rifle buffer weighs 5.1 ounces and the 9mm buffer is 8 ounces. There’s a 10 ounce version for $50

I’m wanting to go heavy enough to defeat semi-automatic cycling. Does anyone have experience with the 10 ounce buffer? I assume that it will still function as a semiautomatic or people wouldn’t want it?

How much weight do you think it will take?

Thanks!

[elmacgyver0]

You got me curious, why do you want to defeat semi-auto cycling?

[jdgabbard]

I used a 10oz buffer with my 9mm build when I was using it with a pistol brace before the pistol brace rule. It worked well with a standard AR15 spring. Some suggest using a 308 spring though... That said, I don't know how it would react in a rifle length buffer tube. Try it and find out.

[jdgabbard]

You got me curious, why do you want to defeat semi-auto cycling?

Likely because 9mm cycling is pretty violent. To the point that I have broken hammer pins due to the violent recoil of the bolt. You need a heavy buffer to slow it down...

[elmacgyver0]

Likely because 9mm cycling is pretty violent. To the point that I have broken hammer pins due to the violent recoil of the bolt. You need a heavy buffer to slow it down...

Slowing it down is a lot different from stopping it completely.

[Barry54]

I don’t want it throwing my brass all over creation for starters. Two, I don’t want the noise of the reciprocating mechanism.

[Barry54]

I used a 10oz buffer with my 9mm build when I was using it with a pistol brace before the pistol brace rule. It worked well with a standard AR15 spring. Some suggest using a 308 spring though... That said, I don't know how it would react in a rifle length buffer tube. Try it and find out.

I don’t want to throw $50 at it and it not accomplish my goal. I’m considering making the aluminum spacer out of brass and adding it in between the bcg and buffer so it adds to the reciprocating weight. Or maybe even have an entire brass buffer made?

[elmacgyver0]

Perhaps you are looking to make a mag fed pistol re-cocked after each shot that you can suppress?
Now it is making sense to me.

[elmacgyver0]

Excuse me, I mean rifle.

[Barry54]

Perhaps you are looking to make a mag fed pistol re-cocked after each shot that you can suppress?
Now it is making sense to me.

Eureka!

So how much weight will it take?

[Moleman-]

You might try making a SS version of the rifle buller + sleeve only with a full diameter top. SS should be the same or slightly heavier than brass and you could add tungsten weights to increase it from there. No idea if that would keep it locked or not but would give you your best chance. They're not as reliable, but gas op uppers with the gas turned off would be a straight pull action.

[K43]

Gas block with no gas port or blocked gas port/gas tube opening. Or, remove Bolt Carrier Key, though that will let gas blow into the receiver.

[Barry54]

It’s blowback. There is no gas system.

[elmacgyver0]

Perhaps one of those old mercury recoil reducers used behind the buffer?
I made a bolt action .38/357 rifle from a demilled Moisen Nangant rifle action for use with a suppressor, because I had the parts.
I understand you want to use what you have and not reinvent the wheel.
I wish I could help you with the weight for the buffer.

[K43]

It’s blowback. There is no gas system.

Sorry, I have no clue then.

[steve urquell]

Barry, I have a 10.4oz buffer in my AR9 pistol. I have used the carbine spring as well as a .308 spring and it cycles pretty much everything including light subsonic loads. Check out Blowback 9's Overmnass project, He has 37.5ozs of buffer in this video. Maybe contact him on this endeavor.

[Barry54]

Well that’s good to know. I just checked my bolt and it’s 14.5 ounces with the original weight in the rear. I’ve got a long way to go apparently.

[jdgabbard]

I guess I must have misunderstood your intent. You're wanting to completely stop the rifle from cycling? If so, I doubt you're going to get there with a buffer. At least not with normal metals, they won't have enough weight really. Tungston has a elemental weight of 74. Lead is 82, Bismuth is 83. You're getting into some pretty rare elements to get the weight up higher than those. Really, you'd need a locking mechanism in order to keep it from cycling.

One option would be to use a Custom McGowen barrel with a barrel extension, and chambered in 9mm, and without a gas port drilled. You'll need to use a 5.45x39 bolt, they can be found: https://www.redxarms.com/545x39-Bolt-p/5102.htm

With those two items you should be able to construct a non-cycling repeater. I'd probably have a side charger if I were going to do such a thing.... It'll be expensive though. Just a guess, about $300 for the barrel. Another $60-75 for the bolt. But it could be done... Whether it would feed easily or not is a different story. But shouldn't be too different from CMMG's delayed locking system they have.

[Barry54]

So in his part five video, he rattled off some parts and I was able to comprehend four kynshot weights after listening to it about half a dozen times and clues from the comments. The specs on the weight say 3/4” long stainless steel and 2.5 ounces. So that’s ten ounces of what’s in his build. My aluminum spacer is about 2-3/4” long. So a custom made solid brass buffer with the diameter left as large as possible might be sufficient.

[Barry54]

I guess I must have misunderstood your intent. You're wanting to completely stop the rifle from cycling? If so, I doubt you're going to get there with a buffer. At least not with normal metals, they won't have enough weight really. Tungston has a elemental weight of 74. Lead is 82, Bismuth is 83. You're getting into some pretty rare elements to get the weight up higher than those. Really, you'd need a locking mechanism in order to keep it from cycling.

One option would be to use a Custom McGowen barrel with a barrel extension, and chambered in 9mm, and without a gas port drilled. You'll need to use a 5.45x39 bolt, they can be found: https://www.redxarms.com/545x39-Bolt-p/5102.htm

With those two items you should be able to construct a non-cycling repeater. I'd probably have a side charger if I were going to do such a thing.... It'll be expensive though. Just a guess, about $300 for the barrel. Another $60-75 for the bolt. But it could be done... Whether it would feed easily or not is a different story. But shouldn't be too different from CMMG's delayed locking system they have.

I’m using the AR platform because it’s relatively cheap and they don’t require a lot of specialty tools to work on in the garage at home.

If I was going to spend real money, I’d find a 223 bolt action donor rifle and get my 24” 9mm blank installed.