Gunsmithing Feeding reamer too fast or maybe chip? Chamber/brass issue

[Dshooter]

Hey guys, had a question for some pro 'smiths out there. Just had a 300 rum built. Stiller predator with a Brux threaded in. I had a dummy round sent to PTG and they made the reamer. This is the first and only cut on it so far. First of I noticed they have it tight spec'ed. Neck and body are tighter than SAAMI. I've shot about 150 loads through it and it's a real hammer! 1 1/8" groups at 400 so far. On the shoulder of the brass though; there are very distinct machine marks. I'm not sure if the smith fed the reamer too fast or maybe didn't blow it out after each cut?? Any ideas? There is also a small bur in the chamber at the body/shoulder junction as I see the mark on every piece of brass. Left photo is fired through my gun, right was fired through a sendero. They aren't as distinct in picture due to SS tumbling....

 

[LRI]

It's a ringed shoulder. I've had this happen with HSS reamers more than once. Polishing it out doesn't work as it typically just alters the shoulder angle.

The best way I've found to resolve it is to take the reamer and feed it literally by hand with the spindle running at a very, very slow rpm. Like10 to 20 rpm. The other way Iis to rotate the tool with the spindle shut off. There's a trick to it. You apply pressure to get the tool cutting. Then back off and let it just rub/burnish for a few turns. You'll feel the tool start to rub and stop cutting. Pull it and check. It's either still there or gone. With the tool fully supported across its length there's little worry of it wandering and distorting the chamber. You'd really have to work to goof this up.

This of course will alter the headspace value. -why it's best to catch this before the barrel is pulled from the spindle as all a guy has to do is push the tennon shoulder a few thousandths to bring it all back into the proper distance.

If you look at your chamber I'd bet a buck the shoulder looks like a vinyl record.

At this point your easiest solution is to prolly pull the barrel, squeak the chamber with the reamer, then assemble to check the HS value. Once you have this you either peel the shoulder or grind the recoil lug. If it's only a couple thousandths you could sand the lug on a granite tile or surface plate. Hopefully your barrel isn't fluted, fitted with a timed brake, or engraved in such a way that it will look goofy once it's put back together.


measure 2x, cut once...

good luck.


c.

 

[Dshooter]

Thanks for that valuable info Chad! Did not know that about those reamers. Yes it should have been caught at the shop it was done at, which amongst other things, is why I'm looking at other smiths to do future work for me. Yes it does have a brake timed on it. I don't have any equipment to do the work here at home. I would more than likely send it out to be corrected with the reamer. I have a spare barrel here for it, for when I burn this one out. It's a bartlein 5r still a virgin. Maybe I'll just run it a while longer until I do the barrel swap then. Thanks for the info!

 

[MikeeBooshay]

Other than not pretty brass, though, it should not hurt anything. If it is extracting OK, and shooting that well, I'd be inclined to leave it be. As Chad says though, that ought to be visible by a little white light inspection. And should have been caught at initial assembly.

 

[skeetlee]

As a fella who spends a great deal of time and pride attempting to cut perfect chambers, I wouldn't want the ring here in there either. However, if your rifle is shooting as well as you say, don't mess with it. Shoot the barrel out, and start over. I wouldn't think less of the boys at stiller either, if they were the ones cutting your chamber. Sounds like the barrel shoots lights out! Shit happens, and that is minor. Not necessarily acceptable, but still minor.
I hate to admit but I have had this happen to me before I knew what to look for. I know look for everything, and I have developed a few little tricks to eliminate situations such as that. I don't have a flush system as some do, but my chambers usually come out picture perfect! Lee

 

[buffybuster]

If the cases extract normally, then this is largely a cosmetic defect. Like a wart on Kate Beckinsale, it's not ideal but won't affect function. Unless it really bothers you, I'd run it until the throat wears and then set it back.

 

[Dshooter]

Thanks guys. Yes I'm going to leave it alone. I was just wanting to make sure it's not hiding a larger problem that could come up. It out shoots me on my best days. I'm very happy with the performance. If I could post pics from my phone or if I figure out another method, I'll post em. No stiller did not do the work. They are and always will be top notch guys in my book, especially Russ. Pierce did the work