Does slop between barrel and action threads affect accuracy?

[25WSM]

First you need to identify what caused your chatter so you can prevent it next time. I'm glad you look at this as a learning experience. I'm still learning little things here and there. The only time I ever experienced chatter on a barrel shank was when I did it between centers and my tailstock moved a little. After bringing the center back snug I took little tiny bites till the chapter was gone. I learned a lesson that day too. A loose tool bit will chatter too. Keep at it and be mindful of your setup and you will be cutting perfect threads. It's good you tried to see how it shot and it's doing good. What the worse that could happen. It shoots bad and then you start over or it shoots good and your done. Good luck on your next one.
Shep

 

[Mram10us]

I have to say the rifle I just did, my first ever, I would be terribly embarrassed to let any of you guys see the threads. They are rough and loose, enough that it had me considering just chopping it off and starting over. I picked up a little chatter on my second to last pass and instead of trying to clean it up with a file, i just tried to cut through it, but it was too deep and i just botched the whole job...but i decided to go with it to see, and surprisingly enough it shot just as good as any rifle i own, and with factory ammo. While i know that is not the precision you all are after, it is sub moa so far and was a great learning experience for me.

I love your honesty! I butchered my share of tenons when I was learning (practice). My first real job was a CA carbon barrel. Talk about nervous with a $600 barrel chucked up. My threads were crumby when I first started learning(before I actually built a rifle) because of a couple things:
1. Tried to take too big of cuts (.020"). I start with .010" now on the first pass and go right to .005" for the next couple. After you see the V starting to form well I go to .003" then finish with light cleanup passes at the end
2. I actually had the half nut engaged just off the number at times! Talk about rookie mistake. I posted pics and had some guys help and others say give up.
You are going to be great at this stuff because you are humble enough to show mistakes and learn vs the guys that post like they are perfect. Keep it up!

 

[bigngreen]

Lathes are different too, I can run carbide lay down inserts and run beautiful threads to spec but my buddy has to run a different type of insert and holder. If your running carbide inserts and your not having a rigidity issue you need to really check your tool hight or change speeds, its usually the last couple passes. I keep a HSS tool on hand just in case it happens, if your too close to give it a real pass pick it up with a HSS and you can usually just ease through. It really help to just keep plugging along as long as you have someone helping, once you have rigidity and tools set you can really smoke threads on and nail specs.

 

[Alex Wheeler]

If you understand a thread joint, you will realize that only one face of a thread is engaged. The back side has clearance. It has to. Clearance is clearance, if its .001 or .005 it doesnt matter for this application. A loose thread, even a very loose thread will not harm accuracy. A tight thread on an action thats not perfect will. I have handled quite a few record setting barrels, not one was fitted tightly. My advice is error on the loose side. In the past many things were tightened up in rifle building, because tighter has to be better. The crank on fit used to be popular, fitted necks, bolt dimensions, chamber specs, among other things. Much of that has gone the way of the dinosaur as testing proved it was the wrong direction. You want some room in a thread joint to allow the shoulders to mate without any bind. You can feel it when its right. Many wont fit up like that with a snug thread. After its torqued the barrel doesnt move.

 

[birdiemc]

I only use HSS for now, my problem was in my setup, too much barrel hanging out unsupported. Next time I'll thread with a live center and shouldn't have an issue. Also as bigngreen mentioned my tool height was probably just a hair too high. Running that barrel did boost my confidence a great deal, and since then I've done a whole bunch of little projects that have helped to move me along...unimportant stuff where the tolerances aren't critical, but I've been shooting for perfection, yesterday I turned down a pin for a table saw fence for my dad and last pass took .015 cut and nailed my dimension within .0003 so I was pretty pleased with that. Just gotta keep getting better the more I run it.

 

[25WSM]

Thanks Alex you just said exactly what I said in post 30. I'm glad we're on the same page. I still have a few aluminum actions that need timed. I'll get them there eventually.
Shep

 

[bushmotornv]

I've only ever done 4 barrels before,but quite a bit of turning of threads for misc parts,but I've gone away from carbide inserts for threading,to hss inserts. It has made a tremendous difference in the threads for rifle barrels. Just my two cents.

 

[birdiemc]

I've only ever done 4 barrels before,but quite a bit of turning of threads for misc parts,but I've gone away from carbide inserts for threading,to hss inserts. It has made a tremendous difference in the threads for rifle barrels. Just my two cents.

What kind of speed are you running threads?

 

[bigngreen]

I started with HSS, really like the Warner HSS insert tooling but after learning what type and how to use carbide I'd never go back, also like cermet inserts. I thread with full form lay down inserts, you can put in high quality threads right to the shoulder, I've cut hundreds of tenons and Im on the same insert!!

 

[Mram10us]

I started with HSS, really like the Warner HSS insert tooling but after learning what type and how to use carbide I'd never go back, also like cermet inserts. I thread with full form lay down inserts, you can put in high quality threads right to the shoulder, I've cut hundreds of tenons and Im on the same insert!!

I use hss for a couple things, but carbide has taken over my shop also. Wish I never would have started with hss. Now I have green grinding wheels and hss blanks I'll never use.

 

[bushmotornv]

What kind of speed are you running threads?

As slow as possible,which is 60 RPM on my lathe. The improvement in thread quality is astounding. The improved finish in general turning is great also. I do still use carbide inserts for roughing though.

 

[Edd]

When you get it figured out, your threads will look like these.
https://www.warner-tool.com/custom-rifles/

 

[25WSM]

Here is a barrel shank I did.
Shep

 

[coontz74]

I use hss for a couple things, but carbide has taken over my shop also. Wish I never would have started with hss. Now I have green grinding wheels and hss blanks I'll never use.

If you would be interested in letting go of your green wheels and blanks, I may be interested in dabbling in HSS....PM me if so inclined....