Gunsmithing "Dialing in" pistol barrel for threads and crown?

[Hellbender]

I have 3 each 5.5" Ruger MKII's I'm getting ready to cut, thread and crown to 4.5" for a new suppressor.

I know how to put it in the 4 jaw to center the muzzle bore, but how will I align/dial in the bore?? Do you make a long sleeve to lengthen enough to get to my spider?

Or am I worrying about nothing and just dial in the muzzle?

These pistols will out shoot most rifles and I don't want to mess up the accuracy.

Thanks!

 

[jacq220]

Re: "Dialing in" pistol barrel for threads and crown?

just dial in the bore on the muzzle end and thread.

 

[300sniper]

Re: "Dialing in" pistol barrel for threads and crown?

if it would fit, i'd use my receiver truing jig. i've precision threaded several sbr 10/22 barrels.

 

[jonaddis84]

Re: "Dialing in" pistol barrel for threads and crown?

I made an extension to reach the rear spider. Those barrels bores are normally cut dead nuts center down the middle anyway, but just another variable to eliminate. I usually have the 3-jaw in before I start, so I part it at 4.5" in that chuck, and I swear it looks like you could thread it in there the bore spins true enough.

 

[hero's machine]

Re: "Dialing in" pistol barrel for threads and crown?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">if it would fit, i'd use my receiver truing jig. i've precision threaded several sbr 10/22 barrels. </div></div>

Me too

 

[LRI]

Re: "Dialing in" pistol barrel for threads and cro

Stuff it in the chuck and run it.

If they shoot as good as a rifle with 1/4 the barrel length then I bet they are pretty straight to start with.

Making an extension just for the sake of indicating a part that isn't even part of the barrel just invites a tolerance stack that gains you nothing.

If you have a collet chuck, try using it first. See just how far out it is. Clamp in a collet, check the tir at the muzzle, then reach into the bore with a long stylus and see how much it changed.

If its out, pop the collet, rotate the part, lock and check again. You prolly got chit betwwen the barrel and id of the collet.

Hope this helps

If your just super paranoid make a mandrel that sleeves the bore. Run it between centers and go for it. It'll be as straight as your tailstock is. This way center is center regardless of how banana'd the thing is. You'll know right away cause if its goofy your mandrel won't even go 1/2 way down the bore before it seizes up.

Good luck.

-id still just use the chuck. . .

C.

 

[jonaddis84]

Re: "Dialing in" pistol barrel for threads and cro

My issue with only using the chuck is Ive tried a few, with the indicator rod and two dials on it you cannot adjust for both indicators with only two axes of adjustment. Because the bore is centered at the muzzle does not mean the entire length is parallel to the spindle.

Im not indicating the extension, Im using the extension to indicate the barrel on all 3 axes.

Again, Im sure it would be fine on 90%, but Id rather not buy someone a new can if I can avoid it.

The other issue is that at 4.5", there is really only about 3" of barrel protruding from the receiver. My 4 jaw chuck is longer than that so I cant get enough muzzle sticking out to even thread it. Also if doing a gun thats gonna get coated its not an issue, but on SS barrels Id rather not run the chuck right into the barrel without something between it, then youre inviting more runout if you do.

Just some food for thought. Not saying Im an expert, but Ive done quite a few of these already and these are the things Ive noticed.