semi auto reamer?

[tensnxs]

I bought a Douglas XX barrel from them and had Douglas chambered in 308win and threaded it. I installed & headspaced it on my semi-auto gun but no gas port yet. I want to shoot it bolt action like first as a baseline for accuracy before I drill the port.

It seems to function well, picks up rounds from the mag and feeds, ejects just like it should. But, when I fired it, the case get stuck in the chamber. It takes a rather hard wack with a mallet on the charging handle to extract it damaging the case rim. There doesn't seem to have a chamfer around the breech end like other barrels.

The breech end of the barrel covers over the fattest part of the case just above the rim/head groove. The fired case just above the rim groove looks has some circular marks all the way around maybe creating a mechanical lock.

Should I cut a slight chamfer? or polish the chamber or is there such thing as a semi-auto reamer I should use to clean it up? What do you suggest I do?

 

[jlmurphy]

If there are grooves in the chamber, it could cause problems, and you can't clean them up without making the chamber oversize. I would polish the chamber, but not too much, the friction of the case against the chamber walls is necessary. Go ahead and drill the gas port, it isn't going to shoot that much differently, and you need the extra force for extraction. Shoot a few dozen rounds and if the ring marks are still there, the barrel will have to go back to the gunsmith.

 

[rcw3]

tensnxs

You have not given sufficient information for one to provide a meaningful and informed response here and supplying some immediate missing information might make things a little more clear:

1. What type of semi auto rifle is it,i.e. an AR-10, SR-25, DPMS LR-308, M1-A, Garand with a 308 barrel, etc.)? There is a significant difference, depending on the type of rifle we are speaking of, in how hard it would be to manually extract a fired case. AR-10 type rifles extract fired cases very hard manually to begin with,as they were never designed for manual operation). If you have an AR-10 type rifle,or SR-25 or DPMS LR-308) and you are hammering on the charging handle to get it open, that is the wrong way to extract a case from the chamber anyway as there are better ways to remove a stuck case, jammed round, etc.

2. Is the ammo you used factory ammo, if so what? Was the fired ammo hand loads, and if hand loads, what's the load, bullet, and brass manufacture? Heck, if the loading is hot for a rifle, in a semi auto like an AR-10, SR-25, DPMS LR-308, I could see why you feel you need a hammer to get the action open and extract the case. If the brass is soft stuff,like Hornady, Norma and Federal) that can exacerbate the situation. Heck if you are running a hotter loading in a bolt gun it can be hard to extract fired cases manually,yeah I have seen a shooter or two that had to resort to hammering on their bolt handle to try and get their bolt gun open and extract a fired case when shooting hotter loads.

Keep in mind, you are trying to do something with a semi auto rifle that is was not really designed for,i.e. to fire it and cycle it manually). You find it difficult to do that and are thinking there's a problem when there may be none.

Robert Whitley
www.6mmAR.com

 

[tensnxs]

The rifle is a FN FAL type with an Imbel receiver. The ammo was Lake City 150gr FMJ. I've shot many other FALs built with surplus kits with the gas regulator turned off and only a few with slightly harder manual extraction. None required banging on the charging handle that hard.

Hope that helps.

btw, what is the better way of removing a stuck case/round from an AR?

 

[tensnxs]

Well, upon closer examination of the fired brass. I discovered there is a protruding ring around the brass 3/8' of below the shoulder. I believe this is creating a mechanical lock preventing smooth ejection of the brass.

I'm thinking using the fired brass, filled it up with JB Weld and use it to polish the chamber just a little. Will that work you think?

What's the proper way of polishing a chamber?

 

[jlmurphy]

The ring in the chamber was probably made by a chip under the reamer when the chamber was cut, I did the same thing when cutting a .22-250 chamber. That barrel is toast. To eliminate the ring you would have to cut a new chamber until the fresh cut had passed the depth of the ring, on a relatively straight walled case, that would mean a long cut. The barrel shank, shoulder, and gas port would all have to move the same amount. You can't polish the ring out, the chamber would be grossly oversize. Whoever cut the chamber owes you a new barrel. My condolences, not the information you wanted to hear.

 

[tensnxs]

Well, I did a little 'chamber polish' search on the web and went ahead and did it before I saw the last post. I used the cased fired from the barrel and made a polish mandrel out of it. I only did a few turns at a time till I can barely feel the ring on the inside of the chamber. I believe I used 800 or 1000 grid polishing compound.

I fired it again with 2 more rounds, they both came out as easy as pulling the charging handle back with an empty chamber. I measured the diameter of the newly fired cases and compared to the old ones. they're only .0005' larger. I was careful in not polishing the shoulder or neck and used lots of cutting oil in the chamber.

BTW, Douglas cut the chambers. The other barrel has the ring too but seems a lot less than this one. We'll see how it goes.