My take on Bolt Gap

[Teyvareb]

Having neglected to introduce myself, and having just recently purchased my CETME, I probably don't do this subject justice, but I'll wing it.

When I first brought mine home, it was in decent shape, dry functioned well, and had a good bore. Not knowing what bolt gap was, I figured eh, I'll give it a few rounds. After having to temporarily fix the floppy recoil rod, (the back end is somewhat rounded at the front and doesn't hold position well) everything went well. A few weekends later I managed to find the old forum (or what I call "Forum Classic") and learned about bolt gap. Promptly checking mine, I ended up with... 0.000

Classic for me. Find something nice and there's always a hidden issue. I managed to find Jorge's current auctions and bought a new locking piece as mine had visible dents where the rollers ride. Putting it in was simple enough, but how to check the gap now? I don't have a set of feeler gauges that span from 0.005-0.010, so I can only get basic measurements.

Inspiration! If you're looking for your gap, and at least have a set of calipers available, try aluminum foil. It's usually 0.001 thick, so a couple folds will bring it to minimum (.004). ---NOTE: It's still best to check with feelers, but this will at least ballpark it. Make sure you measure the foil first. Don't fully trust this measurement.--- A few more strips of foil, and I've got about .007 worth of gap on my original rollers, with a full size (1.835) head. I've also got a full set of rollers coming from RobRTG, so I can set gap for the best. When the rollers come in, I'll use proper feelers, and don't intend to fire this thing till then (NH is still somewhat cold), but it's at least an idea that doesn't involve spending too much money.

[arnaiz]

Having neglected to introduce myself, and having just recently purchased my CETME, I probably don't do this subject justice, but I'll wing it.

When I first brought mine home, it was in decent shape, dry functioned well, and had a good bore. Not knowing what bolt gap was, I figured eh, I'll give it a few rounds. After having to temporarily fix the floppy recoil rod, (the back end is somewhat rounded at the front and doesn't hold position well) everything went well. A few weekends later I managed to find the old forum (or what I call "Forum Classic") and learned about bolt gap. Promptly checking mine, I ended up with... 0.000

Classic for me. Find something nice and there's always a hidden issue. I managed to find Jorge's current auctions and bought a new locking piece as mine had visible dents where the rollers ride. Putting it in was simple enough, but how to check the gap now? I don't have a set of feeler gauges that span from 0.005-0.010, so I can only get basic measurements.

Inspiration! If you're looking for your gap, and at least have a set of calipers available, try aluminum foil. It's usually 0.001 thick, so a couple folds will bring it to minimum (.004). ---NOTE: It's still best to check with feelers, but this will at least ballpark it. Make sure you measure the foil first. Don't fully trust this measurement.--- A few more strips of foil, and I've got about .007 worth of gap on my original rollers, with a full size (1.835) head. I've also got a full set of rollers coming from RobRTG, so I can set gap for the best. When the rollers come in, I'll use proper feelers, and don't intend to fire this thing till then (NH is still somewhat cold), but it's at least an idea that doesn't involve spending too much money.

CETME international intesive care unit !!!

[cimmaronkid]

Be sure to check the gap on the cocking handle tube as this might give you a false bolt gap if there is not a gap. Check the threads with the search option as I believe that we already discussed that again with the bolt gap issue.

By the way, :welcome1:

[Teyvareb]

CIICU indeed! Looks like the previous owner just bailed on this one when the recoil rod went floppy.

Thank you for the welcome Cimmaron! I have yet to check the handle gap, as there is some play in it, but considering it takes as much force as I can muster out of my 135lb body, I probably should... just something else for the list. The original locking piece was badly worn though, the divots on the side were enough to balance the roller in! I'll toss a pic into that thread when I re-assemble it.

Side note: Am I supposed to slide the dime in towards the muzzle side of the cocking tube, or towards the back? I ask because I wouldn't be able to check the gap from the end of the bolt carrier as it's in the handle sleeve...

[cimmaronkid]

Read this series of posts. I think that it will help.

http://www.militaryfirearm.com/Forum/showthread.php?t=180&highlight=cocking+gap

If there is play between the cocking tube piece (never can remember the right term for it) and the stop, and the weapon is still hard to open with the correct bolt gap, then maybe the cocking tube gap is too large and not allowing the correct camming action. Also, make sure the recoil rod isn't bent and if it is, just bend it back straight. If you have an Auto Zone or any other generic auto supply store close by, get a set of cheap feeler gauges. Then measure everything so you can get some better information from the forum.

[Teyvareb]

If I'm taking from that post correctly, the bolt gap should be proportional to the handle gap, correct? If so, I'll need to wait till I get my rollers to set and check everything, by then I'll be able to get a set of proper feeler gauges. Last thing I want is to set the handle gap now, get my bolt to around .02 or so, and be around .04 on the handle.

[jfowl31]

If your gap went to ZERO, you had a gap in the cocking handle... if you didnt, the charging mechanism would have kept the gap open... your fine there... but if its that hard, you probably have too MUCH gap there... thats why the charging handle doesnt quite cam the bolt fully open and thats why its so hard to charge.

[Teyvareb]

It seems to cam well enough, might just be the recoil rod. I ordered a new assembly when I ordered the rollers, we'll see if that takes care of it.

[mprtech]

Did you order a Cetme recoil rod assy.? If you ordered a G3 set you may have opened another can o worms.

[jfowl31]

so youre saying it unlocks easily on the cam, but is hard to pull back the entire way? If so, your rod could be bent... if its only hard at the beginning, its usually an indication of the cocking tube being a little off. And you have to use your full force with no leverage to unlock the bolt. It takes minimal force to unlock the bolt when using the camming action of the charging handle, but some incredible force to do it without that cam to open the bolt.

If its your recoil rod, and you ordered a G3 set, just salvage the spring off the set you bought, and straighten the recoil rod thats on your rifle.

The G3 recoil setup wont fit on a Cetme buttstock housing.

[Teyvareb]

The whole thing is rather monkeyed over. The rear sight is canted to the left, the cocking tube has a bunch of outward bends along the opening, there's all sorts of things wrong with the receiver. It's already got a G3 recoil assembly on it from what I can tell, I'll see what's what when the new stuff shows up.

[-COK-]

Teyvareb, your the kind of people we like around here.

no bitching, crying, or laying blame.

just figure it out, and get-r-done!

i swear, these guys could fix a CETME after it got run over by a tank.
TWICE! lol

bless you, and good luck.

keep us up-to-date please.
thats how things get figured out, ya know? :popcorn:

[Teyvareb]

Damn right! I got bored and took a small mallet to the bends in the cocking tube, bends are gone, and the cocker rides a little smoother now. The sight I don't care much about since I scored one of the Hensoldt's, and as far as the recoil rod goes, I'll get it fixed one way or another. Perhaps I should change the title of this thread to: "I'll fix it or else."

[jfowl31]

If youve got a stamped receiver, youre gonna have trouble with the hendsoldt scope and claw mount................ sorry to add more trouble to the already trouble filled thread.

The scopes tend to "walk" fore and aft under recoil because there's no "saddle" on the stamped models to keep the scope still. If you lock it down tight enough to not move, typically, you pinch the receiver and the bolt binds.

If youve got some know-how and the means to do it, you can weld a saddle or fabricate something to keep the moount still while locked in.

[Teyvareb]

Actually, I seem to have lucked out on the mount. The bolt doesn't bind, and there's more than adequate pressure to secure the mount. We'll see what happens when I get real recoil going on it, but I'm feeling hopeful right now.

[-COK-]

Damn right! I got bored and took a small mallet to the bends in the cocking tube, bends are gone, and the cocker rides a little smoother now. The sight I don't care much about since I scored one of the Hensoldt's, and as far as the recoil rod goes, I'll get it fixed one way or another. Perhaps I should change the title of this thread to: "I'll fix it or else."

with your attitude twards it all,

i think "ill fix it" would cover it!

well done.

[Teyvareb]

Suppose I should get a COG number at some point too...

[jfowl31]

Actually, I seem to have lucked out on the mount. The bolt doesn't bind, and there's more than adequate pressure to secure the mount. We'll see what happens when I get real recoil going on it, but I'm feeling hopeful right now.

Good deal... some get lucky! maybe you're due for some.

[-COK-]

time will tell....

but these boys have a fix or three for that too. :)

[-COK-]

Suppose I should get a COG number at some point too...


im on it bro.

go here, http://www.militaryfirearm.com/Forum/showthread.php?t=20

and ill fix you up proper.

[Teyvareb]

...I probably should have asked what COG meant beforehand, along with the others. I've got an idea, I think, but I should be certain.

[-COK-]

well, i see your COG# in your sigi already,
so i take it you read the history brief in that link i posted?

CETME OWNERS GROUP. the COG.

easy as that.

no dues, no rules, no ranks.

as far as the others, it a whos-who from days past, but never forgotten!

ill try to give you an idea...

Founder of COG ....thats us, go figure?
COA #10434 ........CETME OWNERS of AMERICA
FOG #12 .............FR-8 OWNERS GROUP
FRAG #35 ............FORUM for RESPONSIBLE AMERICAN GUN owners
CSA #10 .............CONFEDERATE SHOOTERS of AMERICA (CETME branch)

[Teyvareb]

Actually, I read through the list first, got my number, posted my reply, then went back and read the rest. Good info for new members though.

[-COK-]

there is more to it than a brief history can describe,
but i think you can see we are not out looking for trouble.

no radical stuff going on here.

d

[Teyvareb]

So, further inspection of my receiver brings up some more interesting details. I apparantly do not have an inner sleeve in the cocking tube. Awesome. No wonder the lever rocks a little. Also, my rails don't line up with the edge of the trunion, not sure if they're supposed to, but it's a pretty sharp angle there. Third, and most importantly, the camming action of the lever is enough to pop the bolt, but not enough to clear the rollers from the trunion, which I'm pretty sure is how it's supposed to work, but there is still a considerable amount of force I need to put in to fully unlock the bolt. Again, I'll wait till my parts come in and see if I can clear up some of the little issues then.

[Big Steve]

Inner sleeve? The only sleeve that is inside the cocking tube is the one that is where the cocking tube connects to the receiver. Are your rails narrower than the trunnion or wider? If they are narrower the bolt head may be hanging up on the rails. All the camming action of the lever does is unlock the bolt. If it is still hard to pull it is either not unlocked all the way or hanging up on something inside. Try this if you can. See how much play you have in your cocking assembly. Then cut your self a shim about the same thickness as your play out of some steel or alum the same size as the end of your bolt carrier. Glue it to the end of the carrier and put the gun back together feeding it up into the cocking handle support taking up the play. Then try to cock and cycle it. If it is a lot easier then your problem is too much play in the cocking assy. DO NOT SHOOT it this way this is only a test. It does the same thing as the dime test only you don't have to take the pin out and disassemble the cocking tube assy.
Steve

[Teyvareb]

Hmm, I was under the impression there was a sleeve that went inside the cocking tube... oh well.

The rails are wider, but they seem a little too far spaced compared to the trunion.

As far as the cocking lever, I might need to replace the lever. Your idea about the gap sounds about right, I suppose the lever might not be camming all the way, which could be the source of the problem.

[nevada]

ALso, check the lever pin. If it's loose or has moved out a bit it can drag on the tube.

[Teyvareb]

Well, it's a good news/bad news day. Good news is that this thing is back together and might actually fire. The G3 recoil assembly did fit, as I've got the g3 wooden stock set, and the rollers did come in. The old recoil rod was the problem, as it wouldn't stay fixed, it would rock and act like a bent rod.

That's about all of the good though.

The bad news is that the rollers won't help. Out of the whole new set I got, 0's, +2's, and +4's, the set I had already were the largest. My gap is steady at .007 after a painful amount of cocking, but the locking piece is the only thing keeping it. There's not much more I can do at this point unless I pop the barrel and re-press it, which I may end up doing. Also, looking everything over, I'm pretty sure it's not 922r compliant, which I'm pretty sure noone would care about in this area, but if someone does notice, I'll be up a creek. I still have to do a full parts count to see, but as it sits now, I'm rather disappointed things didn't go any better.

[jfowl31]

dont get too down... Have you tried getting a new bolt head and LP? The LP develops some pinging where the rollers rest. and the inner surfaces of the bolt head can also wear. If you haven't changed those, I bet that when you do, the bolt gap will get even higher.

[Teyvareb]

That is a new locking piece. The bolt head is full size, with no serious signs of wear at the front face or roller paths. The trunnion might need to be replaced as well, might be pretty badly worn, but I'll wait till the barrel is pressed out to look.

[jfowl31]

Id try the new bolt head first... really. drine, in his rifle before he replaced the shot-out barrel, replaced the bolt head which was full-length before, and got a few more thousandths out of it. .007 is fine... your withing spec, and its settled in there. It wont change for a while unless you shoot it non-stop all day every day. And with a new bolt head, you may be able to boost it up to .010 or higher, which is perfect in my book.

And then if you decide to repress it later, your starting with a mostly new bolt head and LP to set the barrel.

YMMV, but I wouldn't be repressing it just yet. Id shoot that .007 a few thousand rounds until I dropped it below spec... and it may take more rounds than that.

You could name the Cetme: "Bond", since its double-oh-seven.