populating RPK barrel tutorial

[croc4]

Hey Guys,

I have been searching the web and so far no joy, does anyone have a link on how to install the RSB, gas block, FSB, etc on a virgin barrel?

I picked up one of the apex kits and it shows up this weekend, so its time to figure out what to do net .

Thanks,

Croc4

[Rizzle]

Head space your barrel to the front trunnion to begin with. Once it is head spaced drill and pin for the new barrel pin. Then just start populating the barrel.

[tujungatoes]

If you read the build party tutorial written by 69Mach1 there is a bit on barrel population.

[SJgunguy24]

croc, hit me up and I can give you a rundown on what you need to do. I can give you a hand at my place since all of my tools are at home now.

[nicoroshi]

Head space your barrel to the front trunnion to begin with. Once it is head spaced drill and pin for the new barrel pin. Then just start populating the barrel.

This^^^
Remember everything stacks off the front trunnion so set head space FIRST.
Back of RSB is flush with back of front trunnion.
Space GB using gas tube off RSB (don't forget to put the hand guard retainer on before you press the GB on!).
Space FSB using a barrel nut or slant brake to know how far to press it on.
Check all barrel journals BEFORE you press anything for proper tolerance (.002" is perfect).
Be sure to align the GB, and FSB before pinning (avoid cant).

I have done 4 of the Romy RPK using GM rifle barrels.
Those required minor knurling on the FSB, and RSB as well as turning down of the hand guard retainer area. I hope the profile of the Apex barrel is better than that.

[Rizzle]

nicoroshi,

Any tricks to aligning the RSB, gas block, and FSB? I always get them close and then hit the range to make sure they are shooting straight. I would love a way to get the alignment perfect without having to go to the range everytime.

[croc4]

Thanks for the feedback guys, SJgunguy will do.

Nico, the barrels that came in are not undersized, I did a quick check of them earlier, RSB does not go does not go to where it should, meaning that the barrel will need to be turned down a tad in that area, same for the FSB. The lower hand guard retainer fit fine, it could be a tad tighter, but I'm sure once the hand guard is installed the small amount of paly will be taken up

BTW Nico, nice pics!

Edit: Actually the barrels may not need to be turned, I have not measured them, my point was that they are not undersized.

Croc4

[nicoroshi]

Thanks for the feedback guys, SJgunguy will do.

Nico, the barrels that came in are not undersized, I did a quick check of them earlier, RSB does not go does not go to where it should, meaning that the barrel will need to be turned down a tad in that area, same for the FSB. The lower hand guard retainer fit fine, it could be a tad tighter, but I'm sure once the hand guard is installed the small amount of paly will be taken up

BTW Nico, nice pics!

Edit: Actually the barrels may not need to be turned, I have not measured them, my point was that they are not undersized.

Croc4

If you have a micrometer you can check the barrel journals (calipers can lie you know but a micrometer is dead nuts).
Good that they are slightly larger (hopefully .002" larger *fingers crossed for you*). Easier to take a .001 or two off with emery cloth than to knurl an undersized one.

I align barrel pieces mostly by eye but do use clocking rods as well to double check my eye.
RSB is easy. Space evenly between the ears of the front trunnion (if there is a space).
GB, and FSB are aligned by eye, and checked with clocking rods like this (My M85 under construction which live fire sighted the front sight post dead center BTW)>>

[SVT-40]

nicoroshi,

Any tricks to aligning the RSB, gas block, and FSB? I always get them close and then hit the range to make sure they are shooting straight. I would love a way to get the alignment perfect without having to go to the range everytime.

I built a "jig" using some steel.



I clamp the rear sight base to the upright which is exactly 90 degrees to the base.



I use these two upright pieces which are also exactly 90 degrees to the base to set beside the gas block and front sight base. When the gap on each side of the piece is the same it's exactly in line with the rear sight. base.

[wash]

Your front sight spacing is determined by how you want the bipod to fit. I pressed mine on for a slight drag fit so mine doesn't flop around when retracted.

Mine was carefully aligned by eye and looks fine.

Chiz was a huge help, I couldn't have done it as well without his help because I've never populated a barrel before. I could probably do it now but not as fast and probably not quite as well aligned.

[nicoroshi]

Nice jig SVT-40!