Disclaimer: have not made the can yet, as I am waiting for my stamp.
I have been playing around with designs for a can for some of my rifles. It’s large, but volume is your friend with cans. It will be 10"x2", aluminum with machined baffles. Aluminum because it’s easiest to work with the tools I have…I know this isn’t the best material for the intended use, but I’m going for cost and workability on this one. At some point, I can buy the equipment to work with harder more durable materials, but that will take time. My question is will that work effectively for more than 5.56? At the range, I shoot three shot groups with breaks in between. Mostly 100-400 yards. I would like to use it on other calibers as well (300blk, 308, 6.5 cm, etc.)…I don’t expect aluminum to hold up to the higher caliber cartridges…that’d be a bonus. Any input or advice would be appreciated.
I don’t own one. I’ve done some research. I noticed barrel length was a factor for ratings of what a suppressor would handle from one manufacturer. As in the shorter barrels have higher muzzle pressure. So if you are concerned about strength using aluminum, start with the longest barrel you can test with, and lowest muzzle pressure. (300 Blackout)
Yes the bullet goes faster out of a longer barrel. Not because of more pressure. It’s more time pushing the bullet in a longer barrel. But the pressure pushing the bullet is constantly dropping off the further down the barrel the bullet travels. The volume behind the bullet increases.
I have a stamped one that’s 8x1.75 that works for 5.56, but I was thinking that the larger volume and slightly thicker tube/end caps may work for larger calibers. I have an AR-10 that currently has a 20" 308 bbl I can use to test, but the stamp is too expensive for me to blow up lol. I may end up risking it though.
My understanding of them is they are legal if you do the paperwork.
If you get approved and build your own, I would find it advantageous to put the serial number on a durable part and have wear parts be replaceable. If you mess up during building, are you S.O.L. Or do you get to keep building until everything fits right and then put your number on it?
How is it supposed to get marked? Do you have to laser engrave it? Hand engraver? Number punch set and a hammer?
The last thing I do is the sn and all the info required. That way if I mess up a baffle or hole, I can fix it before final assembly. The last one I used a hand engraver and a template. The last one I did has the info on the tube, but I suppose one could put it on a cap.
I looked at the Hodgdon reloading data center and checked three cartridges. 308 with a 150 grain bullet. A compressed powder charge of 46.5 grains gave a maximum average chamber pressure of 60,400 PSI. In 223 a compressed powder charge of 24.0 grains of the same gunpowder I chose for 308 yields a maximum average chamber pressure of 53,300 PSI with a 55 grain Barnes projectile. Now 300 Blackout needs a faster burning rate gunpowder than the other two cartridges so I choose an optimum powder and a 150 grain projectile. The maximum recommended charge weight of 17.2 grains of that powder gives a chamber pressure of 52,800 PSI.
Takeaway thoughts. They all three have similar maximum chamber pressure relative to atmospheric pressure.
The 308 holds twice the gunpowder as the others. Does it generate twice the gas volume?
Lastly the 300 blackout uses the least amount of gunpowder. Also it has the greatest increase ratio of volume behind the bullet from the loaded cartridge to the point where the bullet exits the muzzle. It has the greatest potential of the three to drop pressure. Then at the point where the bullet exits the barrel and enters your suppressor the 300 will have a smaller volume of gas and at a lower pressure to suppress than the other two.
I’m not familiar with the 6.8 cartridge you referenced. If it’s the 6.8 Western hunting cartridge, it might turn aluminum into glitter!
Thanks! I messed up the original post. It was supposed to say 6.5 creedmore, but that didn’t happen. It’s been edited to the intended cartridge. This sleeve will be tapered thicker on the muzzle end with a large expansion chamber that’s also sleeved. It’s all 7075, so we’ll see if it’s strong enough. I have a friend with an airgun compressor that goes to 4500 PSI, so I might pressure test with that after a little more research
I’m still thinking about going with the aluminum tube, but I found a spot locally that I can get 4130 chrome moly tube by the foot in the od/id I need. I’ll have to find somewhere to get the id threaded, but I can figure that out. I’ll stay with aluminum for the baffle and end caps regardless, because I can make those. Threading the id of a steel tube that diameter is outside of my ability and budget.
I don’t know if that’s necessary. The suppressor has a hole all the way through it. Someone way smarter than the people I rub elbows with could probably calculate the maximum pressure inside of it. Just a s.w.a.g. is the pressure inside the barrel behind the bullet as it leaves the muzzle, is in the 3,000-15,000 PSI range for rifles depending upon the cartridge, barrel length, gunpowder it’s loaded with, and a pile of other variables. I’m guessing that the muzzle pressure gets significantly higher as the barrel gets shorter.
I’ve watched YouTube videos where the slow motion guys got a suppressor company to make a see through suppressor for the video. It lasted for at least one shot somewhere in the video. Aluminum is much stronger…
There’s a computer program for hand loading ammunition that I have recently learned it shows calculated chamber pressure and muzzle pressure. I’ll attempt to post an example below.
Cartridge : .35 Whelen
Bullet : .358, 200, LEE C358-200-RF (Weight adjusted to 205 gr)
Seating Depth : .409 inch
Cartridge O.A.L. L6: 2.900 inch = 73.66 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : IMR 3031