Extra heavy buffer for 9mm blowback rifle

[Iron369]

There are a few makes of bolt action 9mm’s.

[country gent]

Tungsten is a problem to machine. Tungsten carbide is normally pressure heat formed to shapes. Otherwise it ground and grinding that buffers shape would be a long slow process.

Filling the buffer with tungsten, carbide weather shot or end mill shanks would be more applicable.

The trick is finding the happy medium where the rifle dosnt function yet is able to be operated by hand easily.

The other is a standard upper "interchangeable" a upper with the locking lugs but no gas tube would give what you want with no problems. With a upper modified to a bolt handle it would become a straight pull rifle. Any spring and buffer would be fine as all it would do is close the rifle. Even better would be a gas system throttled back to just un lock the action making it easier to operate.

[steve urquell]

Tungsten shot is about $50 per pound. Last I checked it was about a $25 increase to get the three little tungsten weights in an H3 buffer vs the regular buffer. A little airspace with the shot should give it the same dead blow hammer effect as an off the shelf buffer. No?

Yep, its a good dead blow buffer as shot.

[popper]

Case head is about the same as 223. Side charger and no gas.

[Barry54]

Tungsten is a problem to machine. Tungsten carbide is normally pressure heat formed to shapes. Otherwise it ground and grinding that buffers shape would be a long slow process.

Filling the buffer with tungsten, carbide weather shot or end mill shanks would be more applicable.

The trick is finding the happy medium where the rifle dosnt function yet is able to be operated by hand easily.

The other is a standard upper "interchangeable" a upper with the locking lugs but no gas tube would give what you want with no problems. With a upper modified to a bolt handle it would become a straight pull rifle. Any spring and buffer would be fine as all it would do is close the rifle. Even better would be a gas system throttled back to just un lock the action making it easier to operate.

I’m not opposed to that. I tried getting a 9mm brass in a 223 bolt and it was just a little too big. I thought about trying a piece of 380 brass, but I’d really rather use the more common. More plentiful and greater variety 9mm brass. I’ve got a 24” blank. The eight additional inches should let me use a couple of tenths of a grain more powder, without increasing the noise level.

How hard would it be to open up an AR 223/556 bolt to accept 9mm?

[country gent]

Not hard at all. with a carbide boring bar it cuts great. probably only need to take .010 out or so.

[Barry54]

So in theory a 223 bolt could be opened up to fit 9mm. My blank threaded to go in a barrel extension. Chambered and headspaceed. Turned down so a barrel nut and free float handguard would work and crown the muzzle.

And maybe it will still feed from the same lower that takes Glock magazines.

Regular or even lightweight buffers and bolt carriers will be enough to get it closed into battery. Fire it and I manually eject with by pulling the charging handle.

Locking lugs are good for 55,000 psi chamber pressure with a 223 based cartridge diameter?

Any chance of firing out of battery like the blowback action will?

Is that the meat and potatoes of it?

[country gent]

On the lock up upper the firing pin is to short until the bolt is rotated fully closed.
The barrel extension may need a little modification as its meant to feed from left right on a 2 stack mag.
Yes the standard springs and buffer should work actually the buffer may not be needed as your operating the action.
Theres actually a safety factor built in to the lugs they are probably good for around 70,000 - 80,000 cup

Boring the bolt out the small amount for the 9mm case probably wouldnt affect the ejector or extractor either.

You may find unlocking and cycling the action with the charging handle a little awkward and difficult. Why I recommended the side bolt handle modification.

[Barry54]

Attachment 328622Attachment 328623

Another thought. There are two versions of the endomag 9mm inserts for using a 9mm upper on a standard ar lower. The steep one is for the ordinary blowback upper. The shallow approach angle is for the cmmg delayed blowback upper.

The blowback barrels sit deeper into the upper than rotating bolt uppers. This may lead to glock magazines not working with this plan?

I’ll try to study up on how the cmmg upper functions and is constructed.

[Barry54]

Attachment 328624

Got this from a CMMG video. Radial delayed blowback. So the hole the cartridge is trying to aim for and enter is further forward. Hence the more shallow ramp.

[jmorris]

How much weight do you think it will take?

Thanks!

On a blowback there is weight and spring. As far as "how much", I have a MAC 10 9mm bolt thats 1lb 12.8 oz and not only does it cycle, it will do so 32 times in less than 2 seconds.

[jmorris]

So in theory a 223 bolt could be opened up to fit 9mm...

Any chance of firing out of battery like the blowback action will?

If a .223 BCG is back far enough to unlock the bolt, the hammer can't hit the firing pin.

[Moleman-]

So in theory a 223 bolt could be opened up to fit 9mm. My blank threaded to go in a barrel extension. Chambered and headspaceed. Turned down so a barrel nut and free float handguard would work and crown the muzzle.

And maybe it will still feed from the same lower that takes Glock magazines.

Regular or even lightweight buffers and bolt carriers will be enough to get it closed into battery. Fire it and I manually eject with by pulling the charging handle.

Locking lugs are good for 55,000 psi chamber pressure with a 223 based cartridge diameter?

Any chance of firing out of battery like the blowback action will?

Is that the meat and potatoes of it?

I've made a few AR15 DI 9mms. A 223 bolt is easy enough to open up and mod the extractor to clear the rim. Or just get a 5.45x39 bolt. I personally know they can feed out of Uzi/colt pattern 9mm and Sten. If the bolt & carrier will clear it you can make it work. The 9mm case is short enough to flip sideways between the chamber and extension lugs. It's enough to jam the gun. You can power thorugh, smooth out the sharp edges on the locking lugs on either side of the extractor and reduce the ejector tension, or grind off the fake lug on the extractor and put a roll pin in that slot to keep the case from being able to pivot too far. The roll pin mod is the way to go. I run buffers without weights. No gas system is easier, but if you put a gas system on it it needs to be short like the one in post #28 . Most 9mm lowers have an ejector built in that will need to be removed in order to use it on a DI9mm upper.

EDIT TO ADD: You'll also have to mod a standard barrel extension or get a "big bore" style. Tromix has a standard Big Bore made from a modified M4 type extension and also a purpose made one without the M4 cuts. If you're going with a single stack mag you can just flatten the bottom center lug on the extension to make a feed ramp. If going with a two place feed the purpose made wider feed ramp is better. I'll see if I've got both types out in the shop and add a pic.

[Bigslug]

Due to the increased popularity of the 9mm cartridge, we're starting to see lever actions - both mag fed and traditional tubes - chambering it. This is probably a more effective path forward than trying to kludge together a blowback autoloader in a way that it doesn't auto load, and you won't have to be a weightlifter to crank out your spent cases.

Consider the Hi Point pistols - these things use an absolute BRICK of a slide with a pretty stiff spring in order to be a functional blowback.

Consider also the British STEN and other 9mm SMG's - A lot of large diameter bolt mass, a fairly stout spring, and a long bolt travel. . .and yet they run.

In theory, you could run a standard AR bolt opened to the proper diameter without the usual gas system. This would be a manual action - - but the problem here is any gas-based system uses that pressure to operate the "lever" to cam the action open and break out sticky cases. Going manual takes away that force and puts it on your arms. The AR charging handle it SUCKS as a lever with which to accomplish that.

[Barry54]

Correct. But the 9x19 doesn’t have as much surface area as other cartridges to swell up and stick...

Show me a 9mm rifle with a 24” barrel that isn’t a semi automatic and I’ll seriously consider it. Otherwise my 24” blank going on something custom is next in line after the existing ar options are exhausted.

The heavy buffer idea was a bandaid thought to get closer to what I want with minimal expensive custom work. And it would have been easily reversed and put back to factory specs when desired. If it’s going to be a cantankerous single shot that won’t feed from glock magazines I already bought, then I’d rather have a break action that’s at least easy to put the cartridge in the chamber.

Again, I respect and appreciate the knowledge of the group here. The Hi-point example is relevant and great along with other examples provided by all.

I’ve thought about buying a new bargain Savage in 350 legend and trying to sell the new take-off barrel. Maybe it would be easier to move than another 223 barrel?

[Dantiff2]

I have been advocating for Rock Island to build a bolt action 9mm on the same platform that they have been using for their 22tcm for more than a year now. The only response I get from them, is that my idea is making it's way up the chain.. I want a 16" barreled 9mm bolt gun with threaded muzzle SOOOO BADD!

https://www.armscor.com/firearms-lis...ical-22tcm-5rd

Dan

[Moleman-]

Rifle from post #28 that is fed from sten mags, 2nd barrel and barrel extensions. Hard to see, but the red arrow pointing to the ejection port is pointing to the ground off extractor lug on the bolt. Red arrow pointing to the barrel is pointing to the ejector slot rail. The rail keeps the short 9mm cases from flipping sideways in the gap between the chamber and extension lugs. The case mouths will end up pitcher shaped from hitting the extension lugs without it. These were my first two barrels, later ones used a 1/8" roll pin which was much easier to install and works just as well. Green Arrow (Tromix big bore M4 modified) is basically same type of barrel extension on these barrels. I just milled the center lug flat and extended that to the bottom of the M4 cuts. Since Tromix started offering them for sale for $10 more than a standard extension I just buy them from him as it's not worth $10 for me to set the mill up to make the cut. There's some glare off the flat area from the flash. They work well for single feed mags. Green/Red arrow is a Tromix specifically made big bore extension without the M4 cuts. The standard big bore extensions will work on a two place feed mag, but these are a little easier to get to work. I took the bare 16" barrel in the pic off a few years ago to thread for a suppressor and apparently forgot about it. I'll cut it down some and thread it, it'll make a nice sbr barrel.

[Plate plinker]

You'd have to make it yourself or have someone make one. They're out there. The gas port ends up being about 1.25" in front of the casemouth.

Thats interesting, its like a HK Mp5 SD then sort of. could just blow the gas forward with the das block installed front to the rear and a long tube. would be a fun experiment.

[Moleman-]

Thats interesting, its like a HK Mp5 SD then sort of. could just blow the gas forward with the das block installed front to the rear and a long tube. would be a fun experiment.

Long gas tube going nowhere is similar to what happens to the gas in a standard upper with the 22lr adaptor installed.

[kenton]

I have been advocating for Rock Island to build a bolt action 9mm on the same platform that they have been using for their 22tcm for more than a year now. The only response I get from them, is that my idea is making it's way up the chain.. I want a 16" barreled 9mm bolt gun with threaded muzzle SOOOO BADD!

https://www.armscor.com/firearms-lis...ical-22tcm-5rd

Dan

How did you contact them? I looked on their website and only saw a support email address. I will gladly send an email in support of a bolt 9mm.