Keyholing cetme after about 100 rounds....

[heavy_weapons_guy]

I just recently built and test fired a cetme built from a centerfire kit with a new barrel.. that I know of before today's shoot it hadnt keyholed any. Today I got about 10 feet from my target, fired 2 rounds and hit the target.. Both bullets keyholed as they hit the front of the target. The ammo used was south african and the barrel is NEW with maybe less than 70-80 rounds down it before todays keyhole event.. btw: the accuracy at 100 yards is totally pitiful too.. I was shooting at a target roughly 1 foot across and 18 inches tall and couldnt hit it worth crap.. However I can hit the same target with my century cetme easily.. Any Ideas as to how I can stop the keyholing or anything??

btw: I was using open iron sights while shooting the cetme.. I am very good with the open irons at 100 yards normally with my century cetme.

Thanks

UPDATE::: Please see http://www.militaryfirearm.com/Forum/showthread.php?t=995

[jfowl31]

Is the pin on the FH protruding into the bore? maybe a REALLY jacked up crown.

[heavy_weapons_guy]

nope, I'm using a screw-on flash hider...

[jfowl31]

screw off the FH and shoot it. It could be threaded crooked, and clipping the bullet as it exits. Usually when bullets keyhole, something is clipping them upon exit... OR the twist rate is COMPLETLY wrong for the bullet weight.

Id bet theres either a burr on the end of the barrel, or its threaded badly and the FH is hitting it. I am pretty sure that the new barrels from centerfire had a normal twist rate.

[rep30cal]

I have to agree with jfowl on this. It could be a burr on the crown or
like a friend of mine experianced, the bullets were hitting the flash
hider, take a close look, there might be signs of copper jacket on the
inside edge of the flash hider.

[jfowl31]

Even most severely shot out bores will stabilize a bullet enough that it wont keyhole.

I could be wrong, but something has to be wrong somewhere around the crown.......

Or... I once heard about a barrel getting warped and bent a bit that caused bullets to tumble. And Ive also heard about barrels that had a bulge in them where the bullet would lose contact of the rifling and then when the bulge would stop, the bullet would do all sorts of weird stuff.

Check the FH for some signs of contact with an exiting bullet, and/or a burr or really messed up crown.

[M1 Tanker]

As JFowl said, the bullet is probably hitting something. Check that barrel REALLY good.

[Geilt]

You said the barrel was new. Was it a BRAND NEW barrel or "mostly new"? Did you thread the barrel for the break yourself or was it already done?

If the crown is deformed you can probably recrown it.

[okie shooter]

Just wondering what changed as you shot the rifle, you said you only noticed the keyholeing after shooting 100 rounds, did the flashhider get dammaged? If it was a problem in the build, shouldnt it have shown up when you started?

[heavy_weapons_guy]

You said the barrel was new. Was it a BRAND NEW barrel or "mostly new"? Did you thread the barrel for the break yourself or was it already done?

If the crown is deformed you can probably recrown it.

Yes, the barrel was a brand new barrel that was pre-threaded for me..

[heavy_weapons_guy]

Just wondering what changed as you shot the rifle, you said you only noticed the keyholeing after shooting 100 rounds, did the flashhider get dammaged? If it was a problem in the build, shouldnt it have shown up when you started?

nope, the flash hider hasnt taken any damage and the keyholing was noticed somewhere around round #90 or so.. But the thing that gets me is that it only keyholed on 2 rounds but no more... I dunno??? Another thing I noticed too is that its accuracy sucks... I tried shooting it offhand with open iron sights at a target 12inches across and 17inches tall and couldnt hit it from just 30 - 50 feet.. I think I need a new barrel?? I dunno..

thanks

[leonidas]

I have never heard the term 'keyholing'. Can anyone explain what this is exactly? thanks

[MicroPilot]

Keyholing refers to the bullet passing through a target sideways. It rather looks like an old skeleton style "keyhole".

https://www.midwayusa.com/guntecdictionary.exe/termlisting?TermID=2973

searched for an image of a keyholed target but couln't find anything.

[jfowl31]

Whats the bolt gap? Those new barrels that came from Centerfire had the barrel pin slots drilled in the wrong spots...... perhaps he installed the barrel to that wrong spot, and its totally screwing something up?

Id guess that the keyholing problem and accuracy problem are 1 in the same. sometimes it makes the bullet tumble, and other times it just screws up the accuracy. Did you ever check the FH or the crown?

[cbear]

You might want to mic the bore and your ammo. What make barrel did you use?

[jfowl31]

If its the normal in the white barrels that came with the CFS kits, they shouldnt be shot out.... I think theres a problem with the assembly.

could be that maybe something got installed outta whack and the bullet gets messed up upon feeding.

I see now that you said there was no contact with the FH. Have you tried unscrewing the FH and shooting it? Checked the crown?

And check what i said before about installing the barrel to the existing predrilled slot. Drine has some pictures of those slots being drilled about 1/8" off... so far off that youll still get a bolt gap that may appear to be in spec because its on the front side of the indents on the trunnion rather than the back side where they should be. If you installed it there rather than rotating and redrilling, you could be narrowly avoiding catastrophic failures.

[heavy_weapons_guy]

Whats the bolt gap? Those new barrels that came from Centerfire had the barrel pin slots drilled in the wrong spots...... perhaps he installed the barrel to that wrong spot, and its totally screwing something up?

Id guess that the keyholing problem and accuracy problem are 1 in the same. sometimes it makes the bullet tumble, and other times it just screws up the accuracy. Did you ever check the FH or the crown?

The bolt gap is 0.. No bolt gap, just like my century made cetme. I installed the barrel in the right spot after I initially saw that the groove cut in the barrel was way off..

[heavy_weapons_guy]

You might want to mic the bore and your ammo. What make barrel did you use?

an "in the white" "new" barrel that came with the kit

[jfowl31]

The bolt gap is 0.. No bolt gap, just like my century made cetme. I installed the barrel in the right spot after I initially saw that the groove cut in the barrel was way off..

Its not installed in the right spot if the bolt gap is ZERO.

Thatd be what we call... the wrong spot.

Dont have a clue if that can cause a bullet to keyhole or accuracy to be horrible, but Ive heard guy say that when they got their gap into spec, accuracy increased. No clue of any truth to that though from personal experience.

How did you install the barrel to the right spot and get 0 bolt gap? Did you set the gap, and not install a pin or something?

I guess my question is... whaddyamean the "right spot".

btw, the Century rifle aint in spec either if its got no bolt gap.

Should be between .004 and .020"

and bolt length should be 1.835" If shorter, its been ground, and should be replaced.

[heavy_weapons_guy]

If its the normal in the white barrels that came with the CFS kits, they shouldnt be shot out.... I think theres a problem with the assembly.

could be that maybe something got installed outta whack and the bullet gets messed up upon feeding.

I see now that you said there was no contact with the FH. Have you tried unscrewing the FH and shooting it? Checked the crown?

And check what i said before about installing the barrel to the existing predrilled slot. Drine has some pictures of those slots being drilled about 1/8" off... so far off that youll still get a bolt gap that may appear to be in spec because its on the front side of the indents on the trunnion rather than the back side where they should be. If you installed it there rather than rotating and redrilling, you could be narrowly avoiding catastrophic failures.

Nope, I havent shot it without the FH yet.. but I will do that this upcoming monday. The crown of the barrel looks good, passes the "bullet test" and is nice and tight. Yes, I did rotate and re-drill the barrel after I noticed how far off the original groove on the underside of the barrel is off. One thing I forgot to mention (that may be the source of this) is that when I put the barrel in the trunnion, there were a LOT of metal shavings and I had to press the barrel completely back out 3 or 4 times to get it right. could taking the barrel out and putting it back in a number of times have caused my problem? The funny thing is that it keyholed twice consecutively at 10 -12 feet when I fired 2 rounds of SA ammo fast into my target BUT when I got back about 30-40 feet, there was no more keyholing that I could see.. the bullets went straight in and out the backside - no problem.. I am going to test fire this gun some more and come back with a range report.. This time with no FH installed. Btw: do you think that using a bipod on the end of the barrel just behind the FH could cause the barrel to bend upwards (and cause keyholing) if it gets hot? Typically when I shoot I fire 10-12 rounds, let the gun cool for several minutes by laying it on the ground without its bipod then I resume shooting.. Do I need a new barrel to stop the keyholing? If I do, whats a good source of barrels??
Thanks

[jfowl31]

Dont shoot the rifle anymore until the bolt gap issues are addressed is my advice...

[heavy_weapons_guy]

Its not installed in the right spot if the bolt gap is ZERO.

Thatd be what we call... the wrong spot.

Dont have a clue if that can cause a bullet to keyhole or accuracy to be horrible, but Ive heard guy say that when they got their gap into spec, accuracy increased. No clue of any truth to that though from personal experience.

How did you install the barrel to the right spot and get 0 bolt gap? Did you set the gap, and not install a pin or something?

I guess my question is... whaddyamean the "right spot".

btw, the Century rifle aint in spec either if its got no bolt gap.

Should be between .004 and .020"

and bolt length should be 1.835" If shorter, its been ground, and should be replaced.


Yeah, I set the gap and installed the barrel pin and everything.. How I got 0 gap is beyond me.. The "right spot" is where the barrel and the inside of the trunnion are flush with each other. if you look on the inside of the trunnion, theres a ring where the barrel goes, I put the barrel right on that ring and drilled / pinned the barrel in..
What do you mean about bolt length?

[heavy_weapons_guy]

should I replace the rollers to get more gap?

[jfowl31]

1. Theres no "set" spot where the barrel goes... the barrel is pressed into place until the gap is perfect. at that point, the barrel is end-milled, drilled, reamed and pinned with an oversized pin so that it wont move but possibly just a couple thousandths during break-in. If thats not followed, and steps are skipped, then bad stuff can happen.

2. The lngth of the bolt head should be 1.835"... Century ground the back of the bolt heads on some rifles to get a flase bolt gap and fool the average consumer into thinking their rifle was in spec.

3. The stickies are your friend... http://www.militaryfirearm.com/Forum/showthread.php?t=296

AND... if you gauled the barrel when pressing it multiple times with metal shavings... it cant be good. Same thing happened to Drine in a past thread... a little searching should bring that one up. search for gaul, and I bet it comes up... or just search through Drine's posts.

[jfowl31]

Im going to bed now... but please do yourself and the rest of us a favor and dont shoot this rifle until you figure out whats wrong.

The accuracy can take a back seat for now. It sounds, from looking at your past posts, and from reading about issues here in this thread, that you just kinda threw this rifle together or something without a really guided way to build the rifle.

One of your posts is quoting a VERY ROUGH outline of how to build a Cetme that Perro posted... All he did was TOUCH on the basics of how its done, and he didnt give ANY specifics of how to do everything the way it should be done, and he even stated in the post that its not near as simple as he worded it. It kinda sounds like you just built your rifle off that one post, and didnt take the time and effort to do it right.

This isnt a rifle that can just be put together... its really got to be "built", with precision measurements, and precision drilling and pressing......... not just pinning everything together and blasting away.

I hope I dont sound insulting if you did take the time and effort to do it all right, but looking at your past posts, and the stuff youve described here in this thread about just installing the barrel to a line, and the bolt gap going instantly to zero, with keyholing bullets and shoddy accuracy, I sorta assume i was built pretty.... well.... nevermind.

I want to stay awake and figure this one out, but Ive got to be up early for work, and I know that there are other guys on here that are more knowledgeable than I that can help you... But I wanted to get it said before I went to bed that you should NOT fire this weapon anymore until the problems are diagnosed just in case you didnt read this thread again until after you shoot it again.

[texlurch]

+1. You have to check the BG while pressing the barrel. Sounds like you didn't, and your gap is way off. Could be the bolt is unlocking too early and bleeding too much pressure off. That needs to be fixed before it gets shot again.
Accuracy.. is it all over the place, or just off to one side, i.e. does it group well, but not at POA? That could be the triple frame being cocked.
The 2 keyholes could have just been a coincidence; squib rds.

[M1 Tanker]

Heavy Weps guy, as they said you didn't install the barrel correctly. The depth is determined by bolt gap...not some set place.

You need to press the barrel out, rotate it and try again. Read what Jfowl has posted man.

[jfowl31]

Hey M1... have you ever heard of a rifle being inaccurate even to the point of keyholing from a bad barrel press? It sounds possible, but Ive never personally heard of it to that extent. Ive heard of guys getting more accurate with an in spec bolt gap because of recoil issues, but can it be so grossly off that it will effect the inherent accuracy of the rifle?

[M1 Tanker]

No Jfowl, I haven't...but we do not know how far the rifle was off from spec. If it was built incorrectly there is no telling what it is capable of. I suspect the barrel maybe bad, grossly out of spec...but with the rifle not be assembled correctly I don't know. For the round to keyhole I thought he had a barrel obstruction or a flash hider smacking it.

[tump]

at 10-12 feet i doubt its keyholing. at that close distance it could be muzzel blast and if your shooting into a burm it could be throw back from the impact. i wouldn't worry about it and concentrate on jfowls tips.:thumbup:

[heavy_weapons_guy]

at 10-12 feet i doubt its keyholing. at that close distance it could be muzzel blast and if your shooting into a burm it could be throw back from the impact. i wouldn't worry about it and concentrate on jfowls tips.:thumbup:

It was definitely a keyhole at 10 feet.. there was no ricochet or anything, no throwback from a berm or anything.. If it had have ricocheted at the distance I was shooting, I would be dead right now... The bullet went sideways into the target like this / instead of making a circular hole like it should have..