8mm Mauser Form 1 can

[lemonysword]

Hello gents, I'm reposting this thead from a couple forums that don't seem to have the userbase or many folks who have made F1 cans before.

I have a Yugo M76 kit that I am slowly working towards getting built, about to place the order for the receiver and I'm on the backorder list for a GM barrel. The flash hider has interrupted threads on it, allegedly for a proprietary Yugoslavian slav magic suppressor, that I think I could get a solvent trap endcap custom threaded for to make a pretty sweet QD setup. Fortunately the flash hider/front sight assembly is not attached to the barrel so I can send it out with an endcap to have the threading done right, and I've already sent some inquiries. Right now I am thinking about doing an 8" D cell tube, though I am willing to go up to a 1.75" OD if a D cell won't cut it. However, one of the places I reached out to has said that he doesn't believe the interrupted threads would be strong enough to support the can without some sort of interior support on the tip of the flash hider. What do you guys think? Has anyone done this before?

- Does the inside of the can need to support the muzzle brake?

- Is a D cell tube going to be wide enough for 8mm Mauser?

- Will less than 5" of baffles be effective enough to make this endeavor worth it?

- If I needed to go up a diameter size, about how heavy could I expect it to be?

- Would premade cones or modified freeze plugs work better as a baffle stack?

Finally an aesthetic opinion question: the M76 will be nicely blued when it is finished (Two Rivers arms is going to build it). I think the deep purple anodizing from SDTAC looks similar to the purple color some steel turns when it's blued and would look awesome on the gun, but what are your thoughts? Pic of annodizing options below.

[lemonysword]

If I had a machine shop make me a precise donut of sorts whose OD was the suppressor tubes ID, and whose ID was the tip of the flash hider's OD held in place between the baffles and the front of the can by a spacer tube, do you think that would be enough to hold support the body of the can? Reference my poor MS paint drawing.

I understand that coarse threads on a flash hider pinned to a barrel will likely not be super concentric. My plan to mitigate this is to do what the DA Wolverine does and have the bore of the baffles get progressively wider towards the end of the can to accommodate for nonconcentric cans.

[whiterussian1974]

I'll try and tackle a few of your questions, but I'd sleepy and won't be able to cover them all.

1-No. Your can doesn't need to support the brake. Just be completely aligned with the bore.
2-Yes, a D-cell should be plenty wide enough. That is the most common size that F1s use for medium caliber rifle builds.
3-6 baffles in a 5" length is the BARE MINIMUM needed to suppress your cartridge. 10 cones in a 6.5" length would be FAR better. But 6 is what some commercial users build. https://www.griffinarmament.com/optimus-9-silencer/
4-Your question is poorly worded. The diameter's "weight" is dependant upon wall thickness and material. A Grade 5 Titanium .050 wall would be much lighter than a 314SS .085" wall.
5-Standard 60* notched cones, or "radials" would work great. There are several suppliers.
Bonus- I would go for Bronze Purple because it looks a lot like Stainless or Titanium. But Deep Purple looks great also. Have you thought of Cerakoting it?
https://www.cerakote.com/project-gallery
I like the Blacks, Grays, Tans, and Browns. Perhaps you will find a shade there that you'd like better?

The body of the can is self supporting. The threads on the muzzle brake attachment point are the only things which hold a can in place. It must be rigid enough not to require any internal bracing.

The threads on both contact points, the muzzle brake and the endcap MUST be true and concentric. Same with the can's body and its attachment to the endcap. Yes, slowly tapering the holes larger as the bullet progresses down the stack is typical of design to help mitigate baffle strikes.

[lemonysword]

Thanks for the reply.

1: So even with the interrupted threads that only really stick out on the top and bottom of the flash hider, it should be OK? I'll throw a pic at a different angle at the bottom.

2: If this was your can, would you stick with a D cell or would you marginally go up in size?

3: So it looks like a 10" tube is what I would want to make this whole endeavor worth it.

4: I plan on doing a titanium tube no matter what. This is going to be a large heavy can at the end of a long barrel, so mitigating weight where possible is necessary.

5: I'll keep my eye out for those.


http://aassniper98.com/en/accessoires/9 ... -m76-.html
This is the only insight I can get on a commercial suppressor for this. I have no idea what the OG military cans were like. I wish there was some amplifying information about it, like the overall length. They have quite a few baffles in there considering how much of the tube is taken up by the flash hider.

[whiterussian1974]

I imagine that the birdcage flash hider is machined from the barrel itself, and not threaded onto the barrel?

I didn't know that the threads were interrupted. No, they probably wouldn't be able to keep your can on, as the shots will torque it and it will come loose and tilt or even fall off. Your cap would need to be spring loaded to stay on a 3-lug mount, and your threads are a bi-lock without enough "meat" to secure even under tension.

If you can remove the flash hider and thread the 1/2" muzzle behind it, that would also give you a great deal more options and better performance.

For this project with the fixed front site armature, I'd use the largest diameter possible without obstructing the sight line. 2 1/8" OD if that is possible. Then you could create a coaxial design with volume around the inner stack. Or simply use the 2" OD cones.

Yes, silencer-zastava-m76 has 9 baffles which is nearly perfect. However, they don't notch the cone mouths, and thus create a laminar flow and central jet of gas. Now we use double notches 180* opposed to create turbulence and prevent the laminar flow and central jet. Also, that short tube covering the flash hider is counterproductive. Your idea is MUCH better to harness and trap the gas in a blast chamber prior to entering the baffle stack.



Here is a "universal rifle" suppressor design that I created and like. It can fire .22 lr - .375 Cheytac. D-cell OD and 12" long, but you would only be using the front 8" as the front sight prevents the reflex volume that I included. You can increase the OD if you wish, it helps by adding volume, but all studies have shown that length attenuates better than diameter for any given volume. And there are reasons for these physics, if you wish to read the research books. Some are Publicly-funded and available online. You would need to contact Capt. Link or Historian for the titles. I forget them. But those 2 Site Members are excellent resources.

[whiterussian1974]

Here is an X-ray of various older model suppressors. We've come a long way since there. I post them only for reference.

Notice how close your design is to #16. The holes in the 1st 2 cones are to create a cross-jet across the central gas jet and use pressure to create turbulence and also shove it off-boreline and force it along the side of the following cone, rather than allow it to simply go through the next cone's mouth. It also relieves the high pressure within the first chambers, so that the metal can be cheaper (weaker) and still not fail from fatigue.

[Capt. Link.]

Just a opinion but a nice carbon steel tube done in a matte blue would look spectacular. You can buy DOM tubing and choose what you like for baffles. The weight is low for this material and life long if cared for.

While you won't quiet the sonic boom with any suppressor, length is better than width..or so I have been told my whole life.

Hiram Percy Maxim's suppressors were 9x1 in 30-06 cal and did a very good job. US1482805A
Using clipped cones and a slim tube should do much better and be very strong. I would suggest 9-12 baffles in a 1.25-1.375 tube.

Dad


I would give thought to cutting the flash suppressor off of the sight tower and setting that back so threads can be machined into the barrel. You can add internal threads to the flash-hider and screw that on when you are not using the sound suppressor.
-CL

[lemonysword]

Thanks for the detailed information guys, that’s pretty much the exact sort of input I’ve been looking for. I’ll have to do some measuring but I believe if I do a 10” can I’ll be able to get quite a few baffles in there. Based on your input I think I’ll trash the 8” idea and go to a 10” can. I’m still not sure yet if I’ll be comfortable with a D cell, or if I’d want to go up to a 1.65” OD can for a bit more volume.

As to the mount, that’s the big question. I have zero desire to modify the rifle in any way. Unlike most AKs, there is no detent pin on the M76 sight post, so I’ll have to rule out a DA wolverine style lock.

Now.. everything I’ve seen about these threads calls them interrupted threads. My browning SA22 has interrupted threads on the quick detach barrel and all you do is put it on and twist it 90 degrees because the recover and barrel both have opposite interrupted threads. I do not know if the intent of these threads were to be a one turn mount like that. I see the reason for the threads being interrupted as more a way to protect the threads from sticking out the side of the rifle and get damaged. The exposed threads are protected by the front sight post itself and the bayonet lug. I’m envisioning a normally threaded endcap that you still have to thread around and around like a normal can. would that make any difference in how strongly it’s mounted?

[whiterussian1974]

Glad to provide you with pretty much exactly what you wanted, lol.

Based on your input I think I’ll trash the 8” idea and go to a 10” can. I’m still not sure yet if I’ll be comfortable with a D cell, or if I’d want to go up to a 1.65” OD can for a bit more volume.

Absolutely! More volume is rarely bad. As long as it doesn't interrupt your sightline, use the bigger OD.

I’m envisioning a normally threaded endcap that you still have to thread around and around like a normal can. would that make any difference in how strongly it’s mounted?

Since you have only top and bottom threads, I think that it might have a bit of wobble. If the threading it tight enough, perhaps not enough to notice.

Looking at your photo, perhaps you could make a 2nd attachment point BEHIND the Sight Tower. It could be threaded, and then after that slide a brace backward and twist to secure behind the Sight Tower. Or simply slide down the threads, 1/2 turn to engage,and the slide a U-shaped block across the barrel behind the Tower. Ruger 10/22s sometimes do this or a set screw to secure a muzzle brake. (No telling how tight the total unit will be, though. Hopefully enough to allow a reasonably tight baffle mouth.)

[lemonysword]

I think I’ll go with the SDTA A cell tube and two blank endcaps. My first challenge is to find a machine shop willing to measure the flash hider threads then drill and tap and endcap for it. From there I can mount the assembly on the flash hider and see how much movement I’ve got. If it seems to lock up tight enough, I’ll proceed with the can. If not, I’ll pass on the idea and sell the tube and endcap on AKfiles, maybe someone else would want to give it a try.

[whiterussian1974]

Yes. These would seem to be perfect for your build.

The 9.7" L, I would imagine? Good choice.

https://sdtacticalarms.com/product/opti ... el-shroud/

"They are made of grade 9 Titanium with a OD 1.75″, ID of approx 1.642 +-.002, .054 wall thickness and lengths as listed. They are 1 11/16″ X 20 thread."

[lemonysword]

So I'm finally getting around to buying the 9.7 1.75" tube and blank endcaps (thanks bidenbux). Still looking for a machinist to custom tap the endcap.

I'm looking at SPC since they have cones for this, but they've got the "pro" cones and 50' cones. Which one should I go with, and, in a 10" OAL can with at least the first 2.5" being taken up by the flash hider, how many cones will I need?

[lemonysword]

https://www.pureperformancearmory.com/p ... cst=custom

I am hearing that these are better than the SPC cones, but they are heat treated stainless. That sounds H E A V Y by the time it's full.

[Capt. Link.]

This may cause you some difficulty in alignment, gas sealing suppressor attachment etc.

1) Cut the flash cage off and thread it internally. Single point thread the muzzle w/a shoulder. Mount the sight tower to barrel. Screw the flash hider cage on for non suppressor use or as a thread protector. A lighter more effective suppressor can now be built without a major change in looks.
2) Cut the cage/half-thread off and make a new one that uses full threads and a shoulder the suppressor can align against. This can be a QD type of mount. You will still need to mount this on the barrel.

This design modification will give you options no matter how you do it.
Build the rear end cap so adapters screw into it. This way the adapter is not a regulated item.