Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.
I recently had a call from a guy saying that a new 22 can I made was shooting way off. I have yet to see it but the most likely cause would, I think be baffle strike, so I got thinking it would be nice to be able to check concentricity off the gun.
That said I have made a great many cans and this is the first time I have had a problem so it is likely a fault with the thread on his gun or mounting.
Anyway armed with the challenge I came up with this little jig, I cut the thread to match the muzzle (they are all 1/2" UNF here), then I drilled and reamed the bore a good tight slide fit on a bit of 1/4" silver steel (I think you call it drill rod). So the can screws on to jig, you then slide the rod down the bore and can easily see if all is ok.
A quick thing to make if you guys needed one
Cheers
Of all the things I've lost it's my mind I miss the most
You also need a device to check the concentricity of the barrel threads. I understand the factory does not always cut threads that are square and/or concentric to the bore.
quiettime wrote:You also need a device to check the concentricity of the barrel threads. I understand the factory does not always cut threads that are square and/or concentric to the bore.
Yes good thinking, though I don't usually get to see the customers gun.
I know thread concentricity is very important though if there has been a problem in the past I have found it is damage or dirt on the mating face of the barrel, that is the can tips slightly when tightened up.
Of all the things I've lost it's my mind I miss the most
quiettime wrote:You also need a device to check the concentricity of the barrel threads. I understand the factory does not always cut threads that are square and/or concentric to the bore.
Yes good thinking, though I don't usually get to see the customers gun.
I know thread concentricity is very important though if there has been a problem in the past I have found it is damage or dirt on the mating face of the barrel, that is the can tips slightly when tightened up.
I have recut factory barrels in the past, for brakes or Flash Hiders some might do but for a silencer. nope.
I have seen threads done by factory's that make very expensive guns, but having the barrel bore in the middle of the barrel or having the threads done the right way...... OHNO.
Yes it is quite surprising sometimes, I have cut few 22's down in the past for integrals, I remember some with the bore as much as 1.2 mm off centre to outside diameter of the barrel.
Of all the things I've lost it's my mind I miss the most
Bought an airgun recently like that, Industry Brand so not even remotely high-end, but it'll make a fun plinker with a regulated bottle on it and shooting 25gr pellets at about 20fpe. Bore is 1.3mm off centre so I had to make a guide rod to centre it in the lathe then turn the last half inch down for threading. Looks wonky as hell with the threads cut so far off to one side. So I'll make off-centre spacer plugs and match those to the bore then use an aluminum tube to shroud the thing, get a bit of integral suppression going while hiding the loopy geometry.
a_canadian wrote:Bought an airgun recently like that, Industry Brand so not even remotely high-end, but it'll make a fun plinker with a regulated bottle on it and shooting 25gr pellets at about 20fpe. Bore is 1.3mm off centre so I had to make a guide rod to centre it in the lathe then turn the last half inch down for threading. Looks wonky as hell with the threads cut so far off to one side. So I'll make off-centre spacer plugs and match those to the bore then use an aluminum tube to shroud the thing, get a bit of integral suppression going while hiding the loopy geometry.
Yea they sure look strange when that happens, you know you have it right, but it just looks so wrong
Of all the things I've lost it's my mind I miss the most
When faced with a problem like this, I typically put a piece of tape over the muzzle end of the suppressor, and fire a round through it. I then fold the tattered piece of tape back into place and examine where the strike occurred. Then I place a shim between the suppressor and the shoulder of the threaded barrel to see if the shoulder or suppressor is out of square. I then work to correct that problem.
I then check for a poorly threaded barrel, by re-indicating the barrel, as if I was going to thread. In this operation I place a dial indicator against a tight fitting pin gage and indicate the bore to as close to zero runout as possible. Then move the indicator to the end of the pin gage and make adjustments until both are no more than .0005 runout at the muzzle and out an inch and half from the muzzle. At this point I place a dial test indicator on the thread relief of the thread. Since the thread relief was probably done at the same time the threads were cut, this is where you will find how poor of a thread job was done. Now the simple fix is to take a skim cut on the shoulder of the barrel to square up the shoulder. This will usually fix any alignment problems. If the thread job is alright, then you look at the suppressor and square the end in a similar manner.
