swhiteh3 Posted August 28, 2015 Share Posted August 28, 2015 I'm writing this for a friend who is not on this forum. The other night while I was there, he was evaluating a used CZ Czechmate he had come across. He had two 9mm major loads worked up for it, and chrono'ed them both. The gun was running well. After chrono'ing the two lots of ammo, he went about accuracy testing the gun, and the targets consistently came back with two groups on them - one in the center of the target, and one 4-5 inches high (this is at 30-40'). We transferred to shooting off a bag, and the same thing happened. Both lots of ammo did the same thing. So I took the gun, and it repeated for me off the bag. I tried shooting offhand standing, and it did the same thing. I tried a lot of my 9mm minor Production ammo, and it did the same thing. Interesting, when we watched more carefully, the impacts alternated from "true" POA to a few inches high *EXACTLY* every other shot. It's the craziest thing I've ever seen. We shot over 100 rounds through the gun on paper, two different shooters, two different positions, three different ammo lots, and EXACTLY every other round goes high. The C-More *feels* firmly mounted, but we did not have metric allen keys to confirm. Everything felt rock solid though. Slide lock-up felt good. The gun ran great. Any suggestions? Has anyone ever seen this kind of issue? Link to comment Share on other sites More sharing options...
tyler2you Posted August 28, 2015 Share Posted August 28, 2015 Saw something similar with a mount that was cracked. Drove me crazy trying to figure out what was going on. Tightened mount screws, adjusted and locked down zero adjustments multiple times until I finally saw the hairline crack. Replaced the mount and all was good. Link to comment Share on other sites More sharing options...
Sarge Posted August 28, 2015 Share Posted August 28, 2015 (edited) Check out this thread from this week. Not identical to your situation but it may give you some ideas of what to check. http://www.brianenos.com/forums/index.php?showtopic=220463&view=findpost&p=2456823&hl=%2B38+%2Bsuper Edited August 28, 2015 by Sarge Link to comment Share on other sites More sharing options...
ivanlun Posted August 28, 2015 Share Posted August 28, 2015 Check the lens if it's loose. Also check for cracks! Link to comment Share on other sites More sharing options...
AWLAZS Posted August 28, 2015 Share Posted August 28, 2015 I just had the exact same thing happen. Cmore had me send it in. The up down adjustments were loose. Link to comment Share on other sites More sharing options...
mro111lland Posted August 28, 2015 Share Posted August 28, 2015 Had similar isues during dry fire noticed dot would bounce in the glass when the hammer droped found front mount screw was tight but back one was loose Link to comment Share on other sites More sharing options...
my00wrx1 Posted August 29, 2015 Share Posted August 29, 2015 I've had the same problem on my CM. It was a loose mount. Sometimes you still have to use a fair amount of strength to get the mount to move by hand. Link to comment Share on other sites More sharing options...
cecil Posted August 29, 2015 Share Posted August 29, 2015 (edited) what thread lock is the most popular for use on the scope mount screws ?? BLUE - RED ??? Edited August 29, 2015 by cecil Link to comment Share on other sites More sharing options...
HI5-O Posted August 29, 2015 Share Posted August 29, 2015 what thread lock is the most popular for use on the scope mount screws ?? BLUE - RED ??? Mount to frame I use red. Scope to mount I use blue. Link to comment Share on other sites More sharing options...
swhiteh3 Posted August 30, 2015 Author Share Posted August 30, 2015 Thank you all for the suggestions. Once he got in there with an allen key, he found one or two of the bolts were only snug, and once he tightened them down, the behavior went away. So it was the simplest fix possible, which is nice. I was surprised that it was a loose mount, given that it felt rock solid to my hands, but as my00wrx1 suggested, it could still be an issue even when it feels firm. Thanks to all who helped with suggestions! Link to comment Share on other sites More sharing options...
9146gt Posted August 30, 2015 Share Posted August 30, 2015 Scott, if I was shooting an open gun with a frame mounted optic I would use a mount like David Sam's does on the M9 Bullseye guns or use locating dowells and 100 degree aircraft screws . Or point out the gun has issues and offer less money for it Tom Link to comment Share on other sites More sharing options...
chase214 Posted August 30, 2015 Share Posted August 30, 2015 I had the same prob with mine I sent it back to cmore and they fixed it about 200 rds later it lost zero I talked to a guy this weekend said he had same prob went with the aluminum cmore and hasn't had a prob Link to comment Share on other sites More sharing options...
my00wrx1 Posted September 5, 2015 Share Posted September 5, 2015 Mine kept coming loose after tightening and trying blue loctite followed by red. Eventually I replaced the screws and used loctite 620. Link to comment Share on other sites More sharing options...
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