View Full Version : Trimming the top rails of an AK-Builder flat

12-13-2007, 8:32 PM
I bought a few AK-builder flats, just in case I messed the first few up. I also bought a rail scribe. The problem is, even with the scribe, I can't seem to get the darned things properly trimmed. How close is good enough? (note -I'm using a dremmel and an angle grinder - NO MILL)! I don't want to completely put together the kit, only to find out that the top rails aren't good enough. I even went with the Tapco flats with the pre-milled top rails just to get out of it. The trouble with that is, that the lower ejector rail doesn't align properly with the other lower rail (it's much lower, due to the pre-drilled hole for the crossbar) - I would think that's not good, but if any of you have had any experience in that area as well, I would like to hear from you. What I have decided to do (for now) is use the Tapco flat with AK-Builder's rails that I can drill myself. Is that crazy? ANY advice is appreciated!

12-13-2007, 10:09 PM
Did you use a jig you made, most of the ones for sale have centering holes to line the flat up in the jig correctly so all holes line up. Do your trigger and hammer pin holes line up or they off as well?

You said the lower rails are off, you should have had to weld those ones in yourself, correct. If they are off bust them out and reweld them.

I wouldnt worry about the predrilled holes in the lower rails, drill new ones as needed or egg them out of they are close.

hope this made some sense, it did to me.

12-14-2007, 7:59 AM
Disregard those lower holes, I like the ones without. ROund them out or you can cut them off. Clamp the lower rails inplace with c clamps or vise grips and adjust unlil it works right. Lower rails are the most nerve racking because they can be a PITA and once they're in it is tough to get them out. Take your time, check fit, take the bolt out, check again (don't forget to grind the ejector if you're shooting 762) then weld. The top rails, GO SLOW! use maybe a dremmel, but a file is better and just take off barely enough to make the bolt slide. The quickest way to screw up your whole build is to cut off too much rail by rushing. Ask me how I know....twice! Also you have to smoothout those rails on the top and bottom to finction. I use a file and wire wheel. You wlii wreck a few before you get it right. Don't get frustrated. When you get it you will from then on and it's really fun.....addictive though.-John

12-14-2007, 1:40 PM
Takes me 20 mins to trim top rails complete w/ cutoffwheel and a file. Mill is just for glory.

12-15-2007, 8:47 PM
I found I had to re-trim the top rails once I put in the center support anyway.

12-19-2007, 3:06 PM
...and again after the rear trunion.

12-19-2007, 3:50 PM
Stick with the AKbuilder flats. all of their FCG and triggerguard holes are where they are supposed to be.

I always install the center support and trunnions before trimming the top rails so I only have to do it once, then I use a dremil with cutting wheels to get close to my scribe line, next I get really close with the orange grinding stones and finish with a file.

12-19-2007, 4:11 PM
Usually, the less Tapco you have, the smoother the build goes. I've found this to be true with both FAL's, and especially, AK's.;)


12-20-2007, 8:30 PM
My next build will be on an AK-builder flat. I have the reamers, but is there supposed to be a little pin or something to locate the reamer into the little FCG holes?

12-20-2007, 8:46 PM
You drill the little FCG hole slightly undersize and then ream to final size. I cheat, I just use my drillbits without a reamer, and everything always works out fine.

12-23-2007, 4:39 PM
Holes drilled... no issues. How many of the black cutoff wheels do you go through cutting the rails? I burn through black cutoff wheels like they are going out of style. They are not cheap either!

The AK Builder flats seem to suck up black cutting wheels much faster than the NDS flats I used before.

This build is going very well so far. Front trunion holes drilled, holes and ejector heat treated, rails welded in, all holes drilled and reamed.

12-24-2007, 6:59 AM
If you have an air compressor Lose the dremil and get a real die grinder 1 cutoff wheel will do at least 5 flats.