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DLT, December 18, 2017 in General Discussion - Any topic is welcome here!!!
Cool test. I'll see if i can replicate it. In light of our discussion, I decided to see if any of my AKM bolts would hand fit on the C39, and to my surprise both my MPAP 92 bolts would fit and rotate. Howeve, both fit a little too tight and the bolt would not unlock when moving the carrier back. I had to rotate the bolt from the tail to get it to unlock. The geometry appears the same with the exception of some extra cuts on the yugo stem. I found info on other sites where folks are using Polish 1960 bolts and carriers as drop in replacements, but alas that well has now run dry.
If you try a substitute bolt, I suggest hard mounting the gun and firing it with a VERY long string from behind something bulletproof.
Full measurements of gun and ammo before and after firing of course.
I'd suggest a minimum of 10 rounds, fired and measured to be safe.
There are fairly cheap somewhat good hardness testing files sets readily available. Some are designed for steel. Others for softer whatever. Also, if you want to, where that lug is scratched or gouged can you match it up where it would rub against the trunnion? I would be curious.
Respectfully. Also consider why that AK may have been for sale?
The scratch just lines up with the locking lug portion of the reciever. There is absolutely zero wear on the reciever. It must be signifinantly better/harder steel than the bolt to continue to appear like it was made today! I was watching a mel64d video on extra bolts and he did say that the bolts are not so hard that they can't be scratched with hand files. As a matter of fact, thats how he fits spare bolts on his rifles, so I'm not really sure what is to be gained by running a file on my current bolt.
Just enjoy the rifle and keep track of the round count you have put on it. If it craps, you have learned something and you can either fix it or just get a different AK. If it doesn't, live happily ever after. That's how I see it.
DLT: Respectfully ...
Smoothing out what appears to be, (not sure also) a ding in your bolt is your decision and we respect that. I was thinking what caused the ding. Are you going to determine the head space .... before firing that AK? Nope, it appears you may have already skipped that basic safety inspection? Have fun. Be safe. Trust but verify.
A pawn shop AK.
Why does a U-Tube video on fitting bolts with files and not very hard stones not surprise me? WE did use very fine dry emery paper to polish bolt head locking lugs way back in the day to fit various surplus bolts with proper head space to what ever project including the $15 buck total Mauser and Springfield projects. Long ago.
Am I that old now? Yep. Yikes!
HB, not really sure what could have caused it. Perhaps the bolt was initially a little too tight and it formed that step after cycling a few rounds. I cant really say. It is already pretty smooth, so i dont want to try and match up the rest of the bolt lug with it. I'm just going to get me a set of gauges and check her periodically after range trips. I greatly appreciate all your advice and that of the other members.
Took her out again today and decided to measure my brass (steel actually...Tula) cases before and after firing to see if there is significant expansion. Well, being a tapered round I really couldn't measure the width, so I measured case length only. To my surprise, it all came back shorter after being fired. What gives with that? Is it because the case is getting fatter?
The shoulder will blow out and sharpen up at the corners, shortening the OAL of the case. "Fire forming." I shoot a few different wildcats that are based off the 223, 6.8SPC, and 308 cases. The first time they're loaded after forming, the case capacity will be less than after they are shot the first time. Usually the brass shortens. The brass that goes to the shoulder has to come from somewhere.
I'd imagine the steel case will do the same thing.
Mixed...your conclusion makes sense. On another note, I decided to cover the finish wear with a sharpie to observe wear firsthand since the bolt already had the wear showing when I acquired it. I'm curious to see how many rounds it will take to start showing the same wear again. Also. I had a friend of mine with extensive manufacturing and fabrication experience look at the step on the bolt and he thinks it may not have formed, but was actually built into the bolt at the time of manufacture to facilitate bolt to receiver lug engagement. But since I've never seen a virgin bolt, I can't verify that. Anyone got a non fired C39V2 laying around to examine?
I would be watching for metal displacement on the lugs, locking area, and the hammer reset nub on the back of the carrier, not so much wear. You might use some calipers to measure the lug thickness from front to back where they actually lock into the trunnion and look for a change in that dimension, assuming that has not already been mentioned. I'm not sure how the locking area in the trunnion could be directly measured with any degree of accuracy without buying an internal caliper. They can be had for as little as $40 or so. Fairly cheap protection for the face and fingers and I am sure you could find fun uses for it elsewhere.
Already knew about the ras. But the C39v2 is a different rifle. I'm not going to worry about it. I've got reference pics to look at to eval wear. If it starts going south, I'll either repair or sell as scrap.
the only difference between the RAS and C39v2 is the receiver. same everything else.
I think they are nice looking rifles, if Century would just keep the QC consistent
modifying the locking lugs on any surplus AK bolt for headspacing is a risky business.. be aware that the lug surfaces are not truly flat, they are helically milled
but I rebarreled a Yugo SKS using a Chinese barrel that would not time up or headspace correctly, and ended up breaking out the file set until it did.. so I'm not one to talk.
Since DLT is in a musical kind of mood.
Another one bites the dust.....
Yep. Definitely gotta keep an eye on it. Haven't had the opportunity to shoot much lately, but I am keeping a round count since I purchased it. At this rate, I'LL reach 1500 in about 40 years!
I keep seeing new posts here by you, DLT, and every time I am thinking it is a catastrophic failure update. Just in case, if it does happen I hope you have some decent eye pro on and some serious $90 secret squirrel operator gloves on, so we can see if the gloves are worth it
Just peeked at it in the safe. Still intact! But seriously, I don't shoot that often anymore due to work and family. If it really starts to concern me, I'll sell it. Really sad though....I wanted something replaceable to shoot instead of my Saigas. Something US made. But I guess the US has yet to figure out the AK.
Shoot the Saigas. Don't worry about preserving them. Live a little and leave some well worn stuff to the kids.
Oh, trust me, I get it. I rarely have time to do any personal shooting. Test firing is about all I get to do anymore. I am making some moves that may change that soon. A separation of the chaff, if you will. I'll still be test firing, but I'll have time to shoot my own stuff again. Party time!
Ammunition is getting so cheap that it may parallel reloading.
Just a brief update. Been shooting the rifle and still no issues. However, after reading on all the drama surrounding the bolt and headspace on these rifles,I decided to invest on a WBP replacement bolt and a set of cip gauges. I noticed some rather interesting things. First, the rifle will not close on a "go" gauge using the original bolt. Hmmm....ok. secondly, the replacement bolt was too large so I had to adjust it to fit. 9 hours later, she finally closed on "go" with pressure. It's nowhere near closing on the "no go" so all is right. I now have a replacement bolt if necessary.
Now here's what I find interesting. The bolt face of the new bolt sits deeper than the original. This translates to a significantly less sloppy fit of the bolt when locked. Even though the old bolt is too tight to close on "go", it wiggles a heck of a lot more when closed. I'm wondering if this slop coupled with too tight a headspace is why the original bolt developed the step on the right side locking area? That basically the receiver lug cut into it due to slight misallignment and fit? What do you all think?
Generally, headspace is checked with the bolt stripped (remove the extractor).
I can't comment on those inquiries from afar. I wish I could help, but there are too many factors to say anything about it with confidence. If it hasn't blown up, spent hulls do not have any alarming characteristics, and it runs good, keep shooting
Tell me about this WBP replacement bolt... what does WBP stand for? Sorry, so much work and communicating to do that I don't have much time to keep up with anything outside of that.
Yes, headspace was performed on fully stripped bolt. WBP is an AK manufacturer in Rogow, Poland. Not sure exactly what WBP stands for. Weapons Built in Poland???
Wytwornia Broni Jacek Popinski (WBP)
Ok. Finally shot it. No explosions and the bullets went exactly where they were supposed to go. I was careful though. I sandbagged the rifle and reached around a piece of plywood between me and the rifle in the event that it went kaboom. Anyway, before going out the ranch a surplus 1960 Polish milled bolt in the white that I was able to locate on gunbroker finally arrived. Since I had all my gauges with me, I decided what the heck, let me check...and guess what PERFECT FIT. Closes on GO with only a few pounds of force and doesn't budge at all on the NO GO. So I took both with me and tried them both out.
So now I've got two functional bolts along with the original. I decided to keep the surplus 1960 in the rifle since it seems to cycle the smoothest of the three.
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