Question about barrel threading relief cuts

[PaulB84]

Just got my Winchester Model 70 featherlight back from ADCO. First time using them, based on a million recommendations I've read over the years and some look at their work first hand

Wasn't expecting this. Every other factory threaded barrel I have has a relief cut between the threads and the barrel that is minimum several thousandths smaller diameter than the threads. A couple random muzzle devices I have work bc they have relief cuts before the threads start. Ones that do not, obviously don't.

I'm pretty disappointed, but want to get some opinions before I contact them.

Below are pics of the threads, along with a random thread protector which obviously doesn't seat against the shoulder and a CAT 1/2-28 titanium HUB adapter on a Rugged Alaskan which does appear to seat properly.

Major thread diameter on my cheap calipers is .493 (seems on the small side to me? Max spec for 1/2-28 is .498 if memory serves) The chamfer at the muzzle looks good and the threads themselves are nice and tight on everything I've put on. But where the relief cut should be is like 8/1000ths larger than the threads and will definitely prevent certain cans/devices being used

Am I tripping here?

EDIT: just went and looked closer at their website. Every example of a threaded barrel they have shows a beautiful, properly sized undercut.

I'm irritated.

 

[PaulB84]

Factory Proof 6.5 and factory Marlin 45-70. This is what I was expecting to see.

 

[E.Shell]

I have about a dozen threaded barrels and ALL of them sow a relief cut behind the threads like you last couple pics.

If your devices don't install properly, I'd send the barrel back to get the job finished.

 

[BBob]

Max spec for 1/2-28 is .498 if memory serves)

Corrected: Max is .4989", Min is .4924". See SAAMI drawing. Chamfer at muzzle much larger than needed even if you think it looks okay, it's not. No self respecting machinist would do that unless it was called out on a drawing or spec but it would still be dumb That crown is more garbage work.

All in all they botched it and it looks like crap. Send them this:

 

[Bluefish]

The grove/relief is needed when manual threading on a lathe. You have to be able to stop the threading tool from moving along the part with the part still turning. Without the groove, the threading tool would leave a cut where the undercut is located. It also needs room to not hit the shoulder with the threading tool.

I suspect the one without the undercut may have been thread milled and not turned. It could have been done on a lathe, but one with live tooling. Not the right way to turn a barrel.

 

[BBob]

The grove/relief is needed when threading on a lathe. You have to be able to stop the threading tool from moving along the part with the part still turning. Without the groove, the threading tool would leave a cut where the undercut is located. It also needs room to not hit the shoulder with the threading tool.

I can thread all day without a thread relief. Thread reliefs, undercuts, chicken slots can certainly be helpful though when threading. The thread relief in this instance has clearance purposes for what may be attached to it other than just the threading operation itself.

 

[PaulB84]

Thanks all. My heart sank when I saw it. ADCO has been recommended so many times, I was sure they would be fine for a simple thread job. I paid $100 total in shipping, plus $140 for the job

Which is peanuts compared to the gun itself that I really love and is now mangled. It's a 22" 270 so not like I have tons of extra barrel to just chop and start over with.

Damn. This sucks.

 

[PaulB84]

BBob,

Am I misreading this?
I'm seeing max of .4989, min of .4924

 

[Bluefish]

Thanks all. My heart sank when I saw it. ADCO has been recommended so many times, I was sure they would be fine for a simple thread job. I paid $100 total in shipping, plus $140 for the job

Which is peanuts compared to the gun itself that I really love and is now mangled. It's a 22" 270 so not like I have tons of extra barrel to just chop and start over with.

Damn. This sucks.

They should be able to come in and cut the relief and shoulder as is. Or find a local smith with a manual lathe and explain what you need.

 

[BBob]

BBob,

Am I misreading this?
I'm seeing max of .4989, min of .4924

No you are not. I mistyped, fingers going faster than the brain

 

[Wrench]

Where are you located?

ADCO dropped the ball and turned that to the major instead of minor.....simple fix for anyone with a lathe. If the barrel is over about 19" I can do it without pulling the scope on my heavy 10.

 

[PaulB84]

Barrel is 22" and the barreled action is completely stripped right now. No optic, rings, bases, trigger etc.

I'm in Southeast Michigan.

 

[BBob]

He said the OD of the threads is ~.093” which is right close the min but not under. I’d be wondering what the pitch diameter is on that job.

2A and 3A thread specs for comparison to SAAMI muzzle device specs.

 

[bnewt3]

Im not a gunsmith, or any kind of machinist, but ive worked with and been around alot of machined parts. It looks to me like the job maybe got shipped prematurely, I am thinking machinist was distracted, someone new working the machine, etc. It looks like galling just below where the threads end too. I dont see anything that isnt fixable.

Every single company makes mistakes.

How they handle them is the true test of a worthwhile business.

Call and talk(not yell) with them. Communicate reasonably. Assume that they will admit a mistake and offer to make it right until it becomes clear they wont.