Suppressors that don't work

[Caster]

Okay, I've been following a guy on another forum about a 9mm suppressor he built on a form 1.  Simple aluminum tube, 1-1/4 ID, aluminum K baffles with a stainless expansion chamber.  

I've been following him because I have a form 1 filed and was planning to use his prints for a 9mm carbine.  

Here's the rub. He says he has ZERO noise reduction.  An 8 inch can with 6 K baffles, cross drilled and a nice expansion chamber.  The whole can was align bored after assembly to .390

 

What could he POSSIBLY have done wrong?  

 

When I get approval, this will be the first can I have made from scratch and I'm not really interested in repeating someone else's mistakes.  

I know there's a "first round pop" some times as the oxygen is evacuated.  BUT multiple rounds and no difference in noise?  Something is seriously wrong.  

Edited June 25, 2016 by Caster

[Wingshooter]

Yeah, that sounds a little strange.  Seems he'd have some level of noise reduction.  Did he use a meter or just "by ear"?

[Caster]

According to his post, his ears were ringing.  

[Wingshooter]

Could he be clipping the endcap? Maybe he's using hot handloaded ammo?

I thought about doing a Form 1 for one also. 

[Omega]

Could be his stack, not enough of an expansion chamber. Then again, maybe he is expecting Hollywood quite, is he using subs?

[MacGyver]

There's not much complexity to a 9mm can. 

You're welcome to check out the internals on my Tirant anytime.  

[Jct1911]

Could be a multitude of issues. Possibility he used an oversize bore? But Zero reduction sounds weird to me. I shot my form 1 22 without the baffles in, it does a pretty good job still. 

I recently just finished a 9mm form 1. Also a 1.14ID. I went with 9 60 degree cones, 8 clipped. 6 are Ti and 3 7075 aluminum. Everything else except booster/piston is Ti. 

Here's a link to pics

http://form1suppressor.boards.net/thread/795/9mm-tube-build-complete

Edited June 26, 2016 by Jct1911

[Junkstack]

On June 24, 2016 at 9:49 PM, Caster said:

According to his post, his ears were ringing.  

If he is shooting supersonics his ears will likely ring still. Some people have such high expectations with suppressors that they think they're going to get subsonic .22lr performance out of any round just because there's a suppressor present. 

[Caster]

I don't think that's it.  I have been talking with this guy on another forum for a while.  He has several suppressors.  It's not a case of hollywood-fluenza.  

 

I chatted with his over the weekend.  He says, fired at close range, a 147g plated bullet is pretty much as loud with as it is without the can.  I know the exact load because it is one I have chronographed myself.  5.3g of AA#5 and a 147g plated bullet runs 975 FPS from my Glock.  It's going to be a touch faster from his 8 inch AR but still.  

I'm trying to get him to send me a picture of his guts.  It'd be a lot easier to figure out from there.  

[Caster]

Ohh, and I told him to try what you said JCT and fire a shot through an empty can with only the end cap and see what happens.  

[MacGyver]

You ever sand cast aluminum?  

[Caster]

No but I know someone who does.  He casts from what he calls "Pistonium" which is melted down forged pistons from race engines.  Apparently he has a steady supply.

He makes some AWESOME Stuff.

 

Here's an ingot mold he made...before machining.  

 

AND, here's a modified Star lube sizer he made from scratch.  The main pieces are cast and machined from old pistons.  

 

[MacGyver]

That's pretty cool.

I've got a lathe, but I think I'd cast k-baffles if it were my can.  I might turn the first one, or just 3D print it.  I'd cast from there, though. 

[gjohnsoniv]

For educational sake, why cast? 

[Caster]

You can get more elaborate and complicated shapes from cast than can be machined.