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Discussion Starter #1
Actually, it is my wife's Cetme. Several years ago, I traded for a century built cetme. It fired well, no problems. I knew nothing about them at the time. A little while later I found out that they needed something called "bolt gap". I researched and learned there was supposed to be a gap between the bolt head and bolt carrier measuring between .004" to.020". (Four thousandths of an inch to twenty thousandths of an inch).
To measure this gap properly, first clear the weapon. Pull the charging handle all the way back and lock it open. Then, no mag or ammo, do the "HK slap" smacking the handle to let the bolt carrier fly forward and lock into place. Pull the trigger so the hammer will maintain pressure on the bolt carrier. Then use feeler gauges to measure the gap between bolt head and bolt carrier.
If you do not have enough gap, it can be improved by replacing worn parts- rollers and bolt head are easiest, or the trunnion and locking piece.
 

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Discussion Starter #2
Century's Drunken Monkeys Strike Again
If you are looking for a cetme, there are some things to look for.
First,after clearing the weapon, how does it cock? The end of the folding charging handle should easily pull away from the cocking tube about 1/4 to 1/2 inch before you feel resistance. If the handle is hard to pull out, or folds out 90 degrees with no resistance, and if it is hard to cock, there could be internal trouble.
Second, measure the gap as stated above. The gap measures "headspace" and timing.
Third, disassemble the rifle. When century built cetmes, the kits were used, some quite worn. So, in century fashion, instead of replacing worn parts to achieve proper gap, the monkeys surface ground the backside of the bolt heads, making a false gap. Sometimes, they ground on the bolt carriers as well. These molested parts should be replaced.
 

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Discussion Starter #3 (Edited)
My cetme had zero gap, my bolt head had not been ground., nor my bolt carrier. All in all, a good build for a century!
To improve my gap, I ordered +4 rollers from RTG and a new bolt head from APEX. +4 rollers are the largest rollers that can be installed in a new bolt head. I did not want to replace the trunnion as it requires welding to the receiver, and pressing the barrel. Cheaper and easier to try the drop in parts. Unfortunately, all new cetme locking pieces are made of unobtainium as no new parts have been made in decades, and HK locking pieces will not interchange.
Replacing the bolt head and rollers brought the gap to .009".
Recently I bought a used locking piece from APEX hoping to improve the gap further, and it did, but only by .001" for a total of .010".
 

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there are cetme parts all over the place nowadays. some nos some "good to exc". on mine i just got (century cetme 308 sporter) bolt gap is at .007". ordered +4 rollers for the sweetspot of .015" bolt gap hopefully. luckily my bolt had not been ground nor the carrier. slightly hard to open but not bad. not use to a long hard pull since im an ak guy. my handle comes open .5" before it starts to push on the carrier.which is in spec.
 
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