Gunsmithing Counterboring inside the muzzle of a barrel.

[338LM]

A buddy of mine recently gave me an AK-47. Inside the muzzle end the lands and grooves are all rusty and very heavily pitted from the crown to about 1.5" deep. Past that point the rest of the barrel and the chamber are in very good shape.
If I chuck the barrel up in a lathe what would be the best way to counterbore the inside of the barrel to clean this 1.5" length up? I will definitely be removing whats left of the lands and whatever else it takes to clean it up.
1) Ball nose endmill to work my way past the crown, then go in with a flat bottom endmill and take to depth?
2) Go in with a ballnose and take to depth?
3) Go in with a flat bottom endmill and take to depth?
Any advice would be greatly appreciated.

 

[gamma]

Re: Counterboring inside the muzzle of a barrel.

I think you'd be best to just cut off that part and then concentrate on recrowning it.

 

[Force_Multiplier]

Re: Counterboring inside the muzzle of a barrel.

counter boring old military rifles is fairly common, I'd want a piloted cutter of some sort personally

 

[Calibur6918]

Re: Counterboring inside the muzzle of a barrel.

Cut it off and permanently add a flash hider to comply with the black suits. BAM fixed and looks cool. Not that ak's look that great to begin with. Plus I doubt all that free bore is great for accuracy. There again, ak's don't = accuracy.

 

[jeepwilson]

Re: Counterboring inside the muzzle of a barrel.

I am no gunsmith so take what I say with a grain of salt.But it would be nice if there was a way you could use a flat bottom end mill with a caliber specific pilot you would be in business.Or can you take a round nose and put in a lathe and turn the end down to caliber specific as a guide as you`re going in the muzzle.I know it can be done in a lathe because the gun I just got built the guy that done it det the riflings back about a .250 from the muzzle.He calls it his truck crown so you can`t gump the crown when putting you`re gun muzzle down in the truck.He also told me when building 22 rimfire sporter class benchrest rifles he will set the riflings back a little at a time to tune the barrel because you can`t use tuners in sporter class.Anyways hope this helps.

 

[gamma]

Re: Counterboring inside the muzzle of a barrel.

If you absolutely have to go that route you'd be better off with a small boring bar. Through in the bore first then go in with your boring bar. You could finish off the crown then with a 60 degree centre drill running at about 40rpm.

 

[Jim See]

Re: Counterboring inside the muzzle of a barrel.

chuck the barrel in the lathe, and use a drill bit +.030 over bore dia. held in the tail stock. No need to crown it when your done. drill the last .010 slowly and it will be a very clean cut.

It's an AK not a bench rifle

 

[338LM]

Re: Counterboring inside the muzzle of a barrel.

I was wondering about using a boring bar and if this would be a better route to go? I assumed that I would run into problems finding something small enough in our toolroom at work to try boring out a 7.62mm diameter.
Also was wondering if I could get away with carefully using a drill.

 

[Brutas]

Re: Counterboring inside the muzzle of a barrel.

The bore might be chrome lined and you will need to recrown it. Cutting it off would be the easiest way.

 

[border_reiver]

Re: Counterboring inside the muzzle of a barrel.

Have done many a piloted counterbore job on target barrels, deep as you like, get the right tool for the job, or just cut the barrel back and recrown.