Thread: Gunwork incl. Barrel threading in Auckland

Originally Posted by Jhon

This 14x1 thread was cut by DPT

Attachment 252936

I didn't undercut the threads on my rifles like this (Personal preference) so it's likely that is what @Jhon encountered. Any suppressors I've made have the internal thread recessed so it's not an issue but maybe DPT don't make theirs like that. In that case a DPT wouldn't fit my rifle as it'll foul on the thread before it hit the shoulder.

Originally Posted by No good names left

I didn't undercut the threads on my rifles like this (Personal preference) so it's likely that is what @Jhon encountered. Any suppressors I've made have the internal thread recessed so it's not an issue but maybe DPT don't make theirs like that. In that case a DPT wouldn't fit my rifle as it'll foul on the thread before it hit the shoulder.

All of our suppressors feature an internal thread relief of approximately 2.5mm in length. Occasionally, we encounter issues when muzzle threads lack a relief cut. These problems often arise due to the non-threaded section being excessively long or having a diameter larger than the threaded portion.

thread relief cuts are common and good practice in any engineering application requiring a shoulder to index against.

I always cut a relief on my threads, when I see one’s without it can suggest the thread has been cut with a die, which is a concern as they should be cut on the lathe. I always insist on having the actual suppressor and cut to achieve a good fit.

As for the shoulder, the minimum I will do is 0.5mm, that being the uncut diameter of barrel is 1mm more than the nominal diameter of the thread……. I prefer more if possible

Originally Posted by LOC

About to get a Kimber cut to a more ‘normal’ thread - do you mind posting a picture of how the shoulder should look in DPT’s view please?

Originally Posted by hakka_ranger

Just out of curious, is that kimber brand new?

Forget to add the quote.

One common threading problem that most engineers are not aware of (and a few 'gunsmiths' as well) is that rifle bores are frequently not concentric with the outside of the barrel, and are seldom truely straight. It is necessary to ensure the bore is running true for the final few inches before the muzzle before threading and this is achieved by correct setting up in a 4-jaw chuck with a precision fitted rod that extends 100mm past the muzzle both internally and externally then checking and correcting the run-out at 10mm and 90mm in front of the muzzle with a dial gauge. Often wedges are needed at the back of the headstock bore to support eccentric barrels. Luckily, modern production methods make this a decreasing problem in quality rifles but it is still prevalent in some makes. Going one calibre up in the suppressor bore can eliminate most minor misalignment problems with no significant degrading of sound suppression.

Originally Posted by hakka_ranger

Just out of curious, is that kimber brand new?

vanished from Timaru if thats what you are thinking

Originally Posted by gundoc

One common threading problem that most engineers are not aware of (and a few 'gunsmiths' as well) is that rifle bores are frequently not concentric with the outside of the barrel, and are seldom truely straight. It is necessary to ensure the bore is running true for the final few inches before the muzzle before threading and this is achieved by correct setting up in a 4-jaw chuck with a precision fitted rod that extends 100mm past the muzzle both internally and externally then checking and correcting the run-out at 10mm and 90mm in front of the muzzle with a dial gauge. Often wedges are needed at the back of the headstock bore to support eccentric barrels. Luckily, modern production methods make this a decreasing problem in quality rifles but it is still prevalent in some makes. Going one calibre up in the suppressor bore can eliminate most minor misalignment problems with no significant degrading of sound suppression.

That's what I found when I started threading my own. rimfire barrels were all over the place, badly bent and the outside running out 0.4mm to the bore at the muzzle. When I checked my Tikkas however I found no bend or runout worth stressing about.
I did thread them setting off the last 100mm of bore as you did, however it was a real challenge getting the shaft 0-0 over the length.

Originally Posted by LOC

vanished from Timaru if thats what you are thinking

Nay just curious where could we buy kimber nowadays since i'm keen on kimber for my next project