Polishing the chamber

[40CalGuy]

Thanks for all the replies guys. As far as I can tell, it is entirely possible that the cases are just expanding beyond the point where they move freely inside the chamber for extraction. With my MagLite, I can see the rust inside the chamber. It's barely a faint brown, and nothing very serious. I would think any of these solutions would work well. And perhaps, the end result will allow me to shoot the cheap ammo. It is also possible that I will simply need to get some brass ammo and try that as well, but I am still only carry 7.62x54r in steel at the moment. I appreciate all the info so far guys.

[Harley Quinn]

dfaugh:
Sounds good to me, I would not use carb cleaner though, I'd use hoppes.
Then clean it up with a few patch's, then a light coat of hoppe's, and shoot it. I believe it would do the job.

HQ

[Unclenick]

I think Dutchy brought the thread back on topic. Actually there are three things that can make a case stick:

1) Overpressure: the barrel and case are both expanded beyond normal limits, but the barrel steel is more elastic than the cartridge case and springs back more than the case so it traps the case like running one into a sizing die without lubricant (though less extreme).

2) A rebated chamber flaw deeper than the spring-back of the case: Even under normal pressure and with normal spring-back the part of the case that fireforms into the defect is still trapped by it.

3) Gluing: as by steel case varnish or other sticky contaminate. This acts like rosin. A Q-tip with a little liquid paint stripper rubbed on a chamber wall would remove enough to diagnose the problem.

4) Surface build-up of rust or other foreign matter: This may trap a case for the same reason given in 2).

In 2), 3), or 4), changing to brass cases should not fix the problem as they will have less elasticity than the steel. In the case of 1), there is either an ammunition load or headspace or chamber dimensional matching problem. That needs to be assessed, perhaps with a chamber cast. All the above would be corrected by setting the barrel back and rechambering, but 3 can also be fixed by cleaning and 4 may also be addressed by the earlier posted methods and without having to access tools for rechambering. Keep in mind that rechambering will create a fresh throat, and will be the most desirable solution if the throat has significant wear.

Nick

[BigO01]

cntryboy1289 since you're a gunsmith I'll phrase this suggestion as a question and direct it at you .
Wouldn't it be better if he used a wooden dowel "$2 at a hardware store" that will fit in the neck area of the bore , wrapped his wet/dry around it and if needed put a little rust remover on the sand paper and work it in and out of the chamber in the direction that a round would travel rather spinning it in the chamber , and then coming back with some 600 grit to finish polising it ?
The reason I suggest this is that if he leaves any small scratches in the bore this way it shouldn't cause the case to hang up on them since it isn't providing a "shelf or lip" for it to catch on .

I was reading up on how to polish a 1911 feed ramp and this same technique is suggested by a pistol smith for this reason . He states that a few minor scratches aren't that much to worry about if they are verticle along the direction of the ramp and not going across it .

It will be a slow process doing it by hand but it shouldn't take more than say an hour by working it for a minute then checking it with a light to see how things are progressing before he continues .

I did my 1911 ramp and it took me just about that much time using first 400 grit then 600 .

[cntryboy1289]

If I am polishing a chamber that I have just cut with a reamer and I have the barrel chucked up in my lathe, then yes, I use a shaped wooden dowel with the same grit of paper wrapped around it with oil on the paper. This would include the 45 barrels like what you read about as well.

If I am polishing my ramps, I start out using a dowel with the paper wrapped around them like you are talking about, but I start with 300 grit paper and then move to 400 and then if i have to, I move on to 600grit. Starting out with too high a grit of paper can make this job take a lot longer than it should also. Nothing wrong with that, but it just isn't necessary.

In this case, the barrel is attached to the gun and there is no reason to remove it just to polish the chamber. This is when I use a length of spring stock in my Foredom tool with the paper taped to it and wrapped around a few turns and then let the loose flap do the polishing for me. I would move it back and forth like I mentioned in my post so as to make sure I didn't leave vertical scratches in the chamber. This can and will do a fine job of polishing the chamber of a barreled receiver. This way won't remove as much material as the wooden dowel so I can really work the paper back and forth to get the surface rust polished out. The wooden dowel can and will remove too much material when the barrel is chucked up in a lathe though and you won't be able to really work the paper back and forth with a dowel in this particular situation.



As far as it goes, I haven't seen the need for a barrel setback just yet. If there is rust in the chamber, it can cause sticky bolt lift as well as make the case hard to extract. Like Nick mentioned, a chamber covered in varnish can cause the same problems so both can be the cause of either problem and the Russian ammo is normally caked with the varnish and causes a many a gun to not function correctly.

I would need to drop a field guage in the rifle before I could say one way or the other if the barrel needed to be set back. You have to remember that this is a military weapon and as such, it was never meant to be shot using reloaded ammunition. I am certainly not saying you cannot shoot reloads, just the rifle wasn't meant to be shot in battle using anything but factory ammo. With that being said, the rifle was meant to be able to function with a wide variety of ammo and within certain specs which vary a good bit between what we as American hunters would consider to be bad headspace. As long as the cases were extracting and the gun wasn't blowing hot gases back into a soldiers face, they went right ahead and shot the rifles. So like I said, I would need to drop a field guage in it to check and see if it actually needs the barrel set back to bring the headspace back into specs.

I do apologize for taking the post off in a different direction and am glad it got back to the topic.

Aminyard, if you are still reading this, I want to apologize for getting ticked at you. I know you most likely just didn't understand where I am coming from with this topic, and that shouldn't be a problem. Any time a gun comes into my shop, I use the best possible solution to a problem. That will also normally be the cheapest and quickest fix as well, but I will never compromise anyone's gun simply to save money. In this and every case, I would start off with the easist fix first and go from there. That doesn't mean the fix isn't as safe as one that would take hours to solve the problem either. Besides, which would you rather pay someone for, a job that took all of about 20 minutes to solve the problem and only used sandpaper and oil to solve it, or one like Nick suggested which would involve using chemicals which there is nothing wrong with, or one that involved me pulling the barrel right off the bat and then chucking the barrel up in a lathe and then polishing the chamber out. I'll hush and let everyone decide which they would choose. Neither of the three would be a wrong way to do the job at hand, but each would cost different from a man hour point as well as parts cost as well.