Gunsmithing Cutting/polishing crown and polishing the chamber

[rg1911]

I have read other posts here and via links dealing with polishing a rifle chamber.

Now that my M1 Garand is back up and running, I have started work on my used Arsenal AK47 (milled receiver) to see if I can get it to shoot better than 4MOA, before resorting to a new barrel (estimated $550 barrel plus installation). So far, both our local AK guru and our lone gunsmith have told me that polishing the crown and the chamber would be almost guaranteed to help. The 'smith did specify that the spot right before the rifling started should be polished without touching the rifling, so now we're into the throat. None of the online references addressed this.

My problem is that the crown cutting and polishing, and chamber polishing, would be $200. Being retired on limited discretionary funds, I have done some initial investigation into the cost and trouble of doing it myself.

For instance, the Brownell's 45 Degree Muzzle/Cylinder Chamfering Cutter & Brass Pilot is $80, a chamber hone (as recommended in one post) is $36 plus another $15 for the required honing oil, and a Power Custom Brass Muzzle Crowning Lap is $10 (plus tax, shipping, etc). I have not yet determined how to polish right up to the lands. So I'm up to $141 plus the delivery charges. Do I want to buy the tools and try the work myself, or pay the 'smith, who has the experience? But that's a side question as I mumble to myself.

The real question is: Leaving aside the crown work, has anyone else polished the chamber of an AK and improved its performance?

Thank you,
Richard

 

[Tperry]

Polishing the chamber of an AK? What's the problem and what are you trying to accomplish? If you aren't having issues leave it alone.

Most precision rifle chambers aren't highly polished but actually slightly roughed to limit brass flow. Like 400 grit or so.

I feel like you're trying to fix a problem that doesn't exist.

I wouldn't expect much better out of an AK.

 

[rg1911]

I understand that 4MOA is within the design tolerances of the AK. I'm simply considering ways to tweak the best accuracy from mine. I don't think getting it from 4MOA to 3MOA to be excessive. Concerning polishing the chamber, I was reporting what I have read in a couple places, and what I was told by a 'smith. The idea of polishing did perplex me since I am aware that the chamber has to hold the case for a brief moment. (At least that is what the majority of the literature reports.)

I also have read and been told that a quality new barrel could be expected to get the AK down to 2MOA. I'm just not prepared to go $550+ down that rabbit hole.

Cheers,
Richard

 

[Tperry]

A recrown is more likely to improve the accuracy. I kind of doubt you'll get 2 MOA but it wouldn't hurt it. I kind of feel like if you have a local smith is trying to charge you 200 for a recrown and chamber polish you should go somewhere else. A recrown isn't 200 and a chamber polish is not needed. People have had decent success with the diy recrown jigs. Then again, if it isn't damaged at all it may not do anything for it.

 

[Hickswr]

Trying to Accurize an AK-47 is like pissing in the ocean in an attempt to raise the level.

 

[MediumSpeed]

An additional factor is what ammo are you shooting - 4MOA seems pretty good for typical AK russian steel case ammo (heck, the xm193 I shoot in my ARs seems to be a 2.5 moa ammo) - additionally, was the barrel new of part of a demilled kit - I would inspect the crown for anything obious before attempting to recrown it. I have no idea about the throat and will defer to other on that

Good luck, have fun!

 

[Bantam1]

Remember that most of the 7.62x39 ammo is not going to get you below 2 MOA at best. Yes there are some lots of some brands that can shoot better, but that is not normal. I have one lot of steel case Hornady that has shot MOA out of my Arsenal Saiga based AK a couple of times. It usually is around 1.5-2. I have another lot of the old white box Russian stuff (I think its Barnaul) from the late 90's that shoots about the same. The regular steel cased and similar is easily 2-4+ MOA.

Accept that the 7.62 AK is a combat rifle for use to about 300 yards. If you stay within the parameters of what the rifle is, the accuracy is plenty acceptable. I'm sure there are some rifles out there that shoot better or worse. I just wouldn't go down the rabbit hole of spending time and money to chase small gains in accuracy unless there is a big problem with it.

 

[camocorvette]

Unless there is a burr or something crazy in your chamber don't even touch that. Cleaning up the muzzle could help.
I've seen aks shoot 8 moa at 100yards and I have a buddies that his rack grade wasr will shoot 1.5 moa at 100.
There are probably a lot of variables coming to play. Mainly barrel and ammo.

Maybe try some Norma brass 7.62x39

For the price of the tools and the cost of experience.. I would just pony up the extra 60 and have a Smith do it. If your so inclined to go that route.

Or just go with the fact it's a commie bullet hose ment for killing men inside of 300 meters. Should still hold a 15 inch group at 300. That's plenty good for what it was designed for.

 

[Yondering]

Barrel crowning (not polishing) might help, if the crown in your AK barrel is bad. Polishing the chamber won't do a thing other than maybe make extraction easier if the chamber is really rough. (It has to be REALLY rough to cause an issue with steel case ammo at low x39 pressures.) Anyone telling you that chamber polishing will make your AK more accurate is full of something stinky, although it does sound like the type of backyard home-brew BS that some of the more ignorant AK fanboys come up with.

I wouldn't trust that smith or anything else they told you, IMHO. Sounds like they were trying to sell you work that didn't need to be done, and charging way more than necessary for it.

The biggest issue with AK accuracy, other than crappy ammo with undersized steel jacketed bullets, is receiver flex and harmonics. If you search online for slow motion videos of AK platforms firing, you'll see what I mean; the whole gun whips around. Until you can address those biggest factors, there's not much point in spending good money on things that your rifle may not even need in the first place.

 

[iceng]

Cotton tip (q-tip for you weirdo yanks), into the muzzle, and pull it out and see if you can catch a strand of hair on anything. If not, (usually) a waste of time. If you have a burr there, it will shave off some copper on the jacket, and that causes the flier. If there is NO damage, bullet it coming out fine. Not withstanding pitting, or not square face, etc..

Rub a cotton tip around, see if you catch a hair... first cheap test.