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Para Driver
October 09, 2006, 09:30
put together a kit on a Armory receiver, and the bolt carrier is really tight.. the bolt won't slide without major foce.. probably need to relieve the rails a few thousands.. anybody been through the same exercise?

instr8
October 09, 2006, 11:04
Been through that with every build. It is to be expected. Top rails have to be trimmed. Deburr the edges with each test, carrier can hang on those too and you'll think it's too tight when it's really burrs holding it. Use just the carrier, do test slides and I use a dremel sanding drum for the finishing, which is what you are doing. Also, I normally hit the edges with a file after I take the drum off of it. The file leaves, not a polished finish, but smoother than the drum. You can also spread those a bit with your hands too. Just don't spread past where they need to be.

You will want to leave the step-down in the rails, just so you know. You can remove some of it if needed, just make sure you leave some.

Valkyrie0002
October 10, 2006, 12:17
Was your receiver a 47, a 74, or a combo. The ejector on the 74 is longer and rubs the carriers on a 47 kit. I did not have any probs with the top rails on the Vulcan receivers I got a couple years ago.

ftierson
October 10, 2006, 22:33
Originally posted by instr8
Been through that with every build. It is to be expected. Top rails have to be trimmed. Deburr the edges with each test, carrier can hang on those too and you'll think it's too tight when it's really burrs holding it. Use just the carrier, do test slides and I use a dremel sanding drum for the finishing, which is what you are doing. Also, I normally hit the edges with a file after I take the drum off of it. The file leaves, not a polished finish, but smoother than the drum. You can also spread those a bit with your hands too. Just don't spread past where they need to be.

You will want to leave the step-down in the rails, just so you know. You can remove some of it if needed, just make sure you leave some.

Actually, after a couple of dozen builds using OOW, AUSA and DCI receivers, this has not been my experience.

In fact, I have only had two cases, one with an OOW 5.45mm receiver and the other with a AUSA 7.62mm receiver, where I had to trim the rails for proper functioning.

Perhaps I have just been lucky...

I have also 'helped' with a number of other builds. Most have also required little tweaking of the rails. except for builds using Ewbanks receivers (which required work on the upper and lower rails and other stuff as well)...

For what it's worth...

Forrest

owlcreekok
October 11, 2006, 08:30
:rofl:

You've not lived until you get one of the VBD "bend-by-hand-and-weld-the-seams" flats into "sliding condition"

Hoo boy ! fun fun fun ! :cry:

I forget the thickness of the blank, but it is , if memory serves, a tad OVER what the 1.5 mm ones are. I don't do metric as I lost my metric tape measure. :rolleyes:

Anyway, the top rails are about four thou thicker than the slot in the carrier. There are NO cuts in the top rails for front trunnion, bolt and carrier. You grind and cut and file and grind and sand till you have Gary Jeter - Popeye forearms. I have one running. Boy do they look and feel great. I never seen me no milled receiver, but these things are heavy and SOLID when done.

Worth the effort ?

Nope. Not unless you are demented like me.

I knocked a Global x Romy together last night. The carrier slid to and fro with hardly any binding at all. No lube on it either. Last Global I put together I had to do a medium amount of relieving.

There is another trick to slicking them up. As I have said before, I will STFU about it. The only time I mentioned it, I got flamed all to hell. But it WORKS ! :shades:

instr8
October 11, 2006, 08:31
Originally posted by ftierson


Actually, after a couple of dozen builds using OOW, AUSA and DCI receivers, this has not been my experience.




Hmmm. I don't know what you could be doing wrong to make the BC work on the first try without having to trim the rails. Maybe you could squeeze the toprails inward a little before you insert the BC. That should work.

ftierson
October 11, 2006, 12:38
Originally posted by instr8
Hmmm. I don't know what you could be doing wrong to make the BC work on the first try without having to trim the rails. Maybe you could squeeze the toprails inward a little before you insert the BC. That should work.

I hadn't thought of that...

I'll have to try that on the next ones...

:)

As I mentioned, maybe I've been just lucky (however, given my normal luck :), I don't think that explains it all)...

Forrest

Para Driver
October 12, 2006, 08:54
I'm going to dremel the rails into approximate position, with a very slight drag.. then lap them with some valve compound to smooth it up... that should result in a smooth glide for the BC, and keep the tolerance tight.. It's not a Swiss Watch for God's sake...

ftierson
October 12, 2006, 10:43
Originally posted by Para Driver
I'm going to dremel the rails into approximate position, with a very slight drag.. then lap them with some valve compound to smooth it up... that should result in a smooth glide for the BC, and keep the tolerance tight.. It's not a Swiss Watch for God's sake...

It's easier to keep the edge being worked on straight with a file compared to using a Dremel. Unfortunately, the top of the receiver is somewhat difficult to get at with the top rail just below it...

You might try straightening the edge with a file after hogging out most of what needs to go with the Dremel.

One of the two receivers that required work on the top of the receiver rail (not the actual top of the rail itself) also required that some material had to be removed from the end of the ejector to allow the bolt to clear it. Some care is certainly needed when doing that because it would be easy to remove too much from the tip of the ejector and end up with too little to catch the base of the cartridge case to eject it. I'm trying to remember, but I'm pretty sure that it was the AUSA 7.62mm receiver that required that extra touch.

Good luck with your receiver. Your plan sounds fine to me...

Forrest

Para Driver
October 16, 2006, 15:46
this turned out fairly easy, Global says the spec is 25.0~25.1mm.. I figured that as .984 on the minimum.. so I used my calipers, and opened the rails with my dremel and grinding wheel in nice smooth strokes until they were .980-.982.. I figured a little snug is better than too loose.. so guess what, it runs smooth without any further work..

now off to the range next weend for a few test shots...

ftierson
October 16, 2006, 17:01
Congratulations on a job well done...

Have fun shooting that hummer...

:)

Forrest

Para Driver
October 16, 2006, 17:09
I may still lap it with some valve grinding compound, just to really slick it up... but not very much..

troubleticket
October 24, 2006, 07:08
How do you adjust headspace on an AK?

owlcreekok
October 24, 2006, 07:26
How do you adjust headspace on an AK?


You know how the barrel pin is across the barrel, through the trunnion ?

That hole is drilled so as to position the barrel at the proper place for headspace. How one would go about changing that dimension would be, in my opinion, not worth the hassle. ie- weld up the notch in the barrel, turn it down and re-drill. I would not want a rifle that had the barrel welded up like this. That is a lot of weldment and a lot of heat. I would dump the barrel and buy a matching kit.

YMMV

Para Driver
October 24, 2006, 09:04
1) you can try different bolts, that worked for me recently...
2) you can move the barrel to obtain the correct HS, then redrill the hole for an oversize pin.. I think the standard is 7mm and you can move up to an 8mm pin??

owlcreekok
October 24, 2006, 09:08
Duhh, thanks for that, Paradriver. I had posted all I knew about it. After learning that <$100 gets a matched up unit, I pretty much forgot the rest.

Lol

Para Driver
October 24, 2006, 11:46
OWL,
you are 100% spot on, not to weld on those barrels.. I nicked one hard, and I'm probably going to deep-six it.. because they are heat treated and hardened and welding could weaken that.. a new barrel is only $50 anyway.. why risk it?