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223 mix-master AK rebuilt

5K views 26 replies 8 participants last post by  mtdew 
#1 ·
I put this together on the cheap years ago. Worked great but was butt ugly. Bulgarian bbl, bolt, Romy parts kit. I just added refinished Bulgy 74 wood, Childers Polish receiver blank. Sandblasted everything, parked and painted with Baking laquer. I like it alot better now. This is the one I rebuilt using the virgin trunny. I will shoot the crap out of it and report on how the trunny holds up.
 

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#2 ·
Was your barrel from K var with 23mm dia. ? If using the Romy trunnion 23mm? I ask because I want to build one and from other forums they mention the gas port on the barrel doesn't line up with the gas block. I may just use the barrel from AK builder but would like to know how you did yours Looks Great.
 
#4 · (Edited)
Yes, its the k-var bbl and bolt. What I did to make the gas port line up with the 47 gas block was to figure out where the hole in the GB needed to be then drilled a hole from underneath like a 74 trunnion is drilled. I just had to make sure that the hole I drilled intersected the gas passage in the 47 GB. This puts the hole directly thru the rear pin hole, but I was still able to pin it. Top: 47 GB, Bottom: 74 GB
Now the easiest way would have been to get a 74 GB and be done with it, but when I built this thing I was very poor!
 

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#7 ·
That's something I'd wondered, what would be ,,or is there a "standard amount" of gap to open up a comp/flash hider to, compared to the bullet dia,,any specific measurement/spec for best performance ? Or just enough so it don't jangle through.

Damn now I've built and AK platform,,it opens up all kinds of other questions I'd never really though much about ,, just doing mostly 99% bolt guns before.
 
#15 ·
That's something I'd wondered, what would be ,,or is there a "standard amount" of gap to open up a comp/flash hider to, compared to the bullet dia,,any specific measurement/spec for best performance ?
I read up on that once. .015" is a popular figure. Less is good; it was just that .015" seemed to accomodate the usual centerline errors from the barrel, bore, barrel threads, brake threads, and hole(s) in the brake.

Remember, some bullets wobble as they leave the muzzle and stabilize downrange. So if your brake opening is very tight, one brand of ammo may work fine while another with a different bullet shape may see strikes on the brake opening.

Efficiency degrades as clearance opens up, so starting tight and enlarging until you don't see any strikes is fine. Production stuff has to leave enough clearance for worst-case ammo and tolerance stack.
 
#8 ·
I don't kno w about standard amount of gap all I know that when I put my 74 muzzlebrake on my 47 It was going be a tough squeeze to get a 7.62 projectile through a 5.45mm hole so I opened mine up. I put it in a vice and drilled the opening up to well beyond 7.62mm, eventually I went back to the slant ( tapco) brake
 
#11 ·
I just checked 2 stock 74 brakes and they measure .339 & .340. Way more than needed for .224. Of course you have to take into account the brake not being concentric to the bore. I like to use a length of close fitting rod to check the clearance.
 
#12 ·
:dunno:The reason I'm asking is that I've been watching several video's on brakes being put on bolt guns with good results and I have a "Long Tom" 06 I'd like to shorten up some, and add a break to,,another Springfield 03 that I'd built probably,,,, 25-30 years ago or so ago.

It's a really nice gun and all but just a bit ungainly for anything but a bench or long range truck gun, lots like some of the old Weatherby's. You sure get tired hauling that beast around all day let me tell ya, it's all there. It needs an updating,or at least a diet!! But not sure just what I'll do on it just yet,,it's pretty damn nice as is, but just a bit ungainly. And I'd just like to improve that somehow.

The thing I'm having to consider carefully is that optimal barrel length in 06 with slower burning powders and heaver bullets, that I like to use in that gun, is in the 22-24" range, and it's 26 now,,so I'm not going to gain anything really there on either count and it's a bit to fancy really to put into a composite stock to shed some weight and still have it look right. Bolts chromed, polished finish, ect,,see what I mean about not really fitting in a composite sock, and looking right?

But I do have a 8mm Mauser that could use it more,and probably would fit the bill better in a composite stock configuration and a break. I may just do something to that one?

I just want to try out a brake on a harder kicking bolt gun,,just for the shits of it, if for no other reason and those are the only two I can think of I want to do something different with. And I like gathering all the info I can get before hand, it makes things much easier,and better.

That's why all the brake questions.
 
#13 ·
No problem, t. I like brakes/comps but the folks next to me at the range don't! Its not too bad for them when its just a 223 but when someone gets out their .500 martian magnum with a boss brake on it and your sitting beside them the concussion will flatten out the side of your head!
You know, one of the best brakes I have found for a 30 cal is one you already have. The AMD 65 brake does a fine job of keeping the recoil down and I swear I think it helps accuracy. I have put them on .308 win, 8mm mauser, 7.62x54r with good results. And their cheap!
 
#14 ·
Ditto!!! I love the AMD-65 brake on my PSL's. I swear it has less kick than a standard 47 with a slant brake.
 
#17 ·
Good stuff, TRX. I have also looked into this subject and found that some go as little as .010 over. That's pretty tight, but like you said, smaller is better. I also read that too big can degrade accuracy over a bbl with no brake/comp. DK about that, but it is interesting.
 
#18 ·
Another good thing about the AMD 65 brake is they have a lot of "meat" on them. They can be turned down, or machined flat on the sides, and you can remove the "cone" on the front.
 
#20 ·
Today I put 30 rnds down range with it, ran great. When I got home I field stripped it to look at the trunnion locking lugs. Remember we had some questions about the heat treatment and such of this unknown trunny. Well, so far, all is well. No peening or anything out of place. I know 30 rounds is not enough to tell whether this trunny is gonna last, but I have a feeling its gonna be allright. I'll put more rnds thru it when I get more time and let you folks know how she fares.
 
#23 · (Edited)
Update on the front trunnion. After about 200 rounds the right locking lug is starting to peen over. Just a tiny bit, and it may last forever, but it's not something I'm comfortable with. I have found out that it's one of those Polish V-Project civilian company CAST trunnions. I have ordered a comblock forged trunnion to replace it with.
 
#25 · (Edited)
I used what I had on hand, a 45 deg gas block. The holes didn't line up, but I fixed that. Originally this had a romy 47 trunnion but I converted it to use AR mag, but wasn't happy with the right locking lug being so much smaller after converting, so that's when I got the crap trunnion, not knowing it was cast. Live and learn. Anybody need a weak trunnion for a low pressure or blowback build? EDIT for lol!
 
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