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7600 lock up issue

PostPosted: Sat Aug 04, 2018 8:31 pm
by Wigwam
Hi everyone, I have a 7600 carbine in 3006. It has been shot very little. Today I was at the range trying some loads I made for it that shoot very well. A mild load of h4895 with 150 hornady sst's. They shot fine. I happen to have 3 boxes of Nosler trophy grade 165 accubonds so thought I'd try them. 1st one I shot locked up the bolt. I got it open and the primer was peirced. I thought the case was stuck but when I worked the bolt with it empty it wont close and actually sticks so you have to use force to open it. The bolt doesn't rotate so it won't lock up. I've used the same lot of ammo in my Winchester extreme weather with no issues. The gun is spotless inside and out. I've shot about 40 rounds in it all mild hanloads toi keep the muzzle flash down. This is the 1st factory load I've shot. The previous owner said he never shot it. I've had it about a year and just started playing with it. Maybe Remington needs to look at it.
Thanks

Re: 7600 lock up issue

PostPosted: Mon Aug 06, 2018 9:46 am
by mauser9
Geez wonder if that pierced primer screwed the bolt up with too much pressure. I have a Model Four in .270 Win. and I stick with factory ammo myself.

Re: 7600 lock up issue

PostPosted: Mon Aug 06, 2018 1:20 pm
by Wigwam
I pulled it apart last night and found the culprit. Very simple teardown. In the back of the bolt is a pin that holds the firing pin in place. There's not much metal above the pin. That upper area cracked and bent back enough to create a small bulge so the bolt rubbed inside the carrier. Looks to me like a factory weak point. My cousin brought his 7600 over for me to look at as a reference and mine never slid as easy as his. Maybe this situation started in production and the firing pin slowly changed position. I have an old 7400 I can grab the bolt out of and try, I think the bolt is the same. If not I'll be getting one somewhere else. No hurry it's not my primary deer thumper.

Re: 7600 lock up issue

PostPosted: Mon Aug 06, 2018 1:49 pm
by Wigwam
Mauser9 you could be right. The retaining pin and firing pin did make contact at some point but was the bolt already out of line or was it all from the peirced primer. I've been shooting for 45 years and handloading for 35 and have never peirced a primer. Like the saying goes there's a first for everything.

Re: 7600 lock up issue

PostPosted: Mon Aug 06, 2018 4:03 pm
by mauser9
Well seemed to function OK earlier so I can't help but think that pierced primer caused the problem. Nice gun and not cheap so I would definitely send it to Remington or a qualified gunsmith for repairs if you fix does not work. No idea if the bolt of the 7400 will solve the problem.

Re: 7600 lock up issue

PostPosted: Thu Aug 09, 2018 3:33 pm
by Wigwam
Installed a 7400 bolt and firing pin. Works smoother than ever. I'll have chance to try it this weekend.

Re: 7600 lock up issue

PostPosted: Thu Aug 09, 2018 6:29 pm
by mauser9
Hope all goes well. Plan on shooting my Model Four this weekend to see if the scope is still on the money. Had it since 81. No problems but does not get much usage so cannot give realistic review concerning jams and feeding. Newer design on this one.

Re: 7600 lock up issue

PostPosted: Fri Aug 10, 2018 5:26 pm
by Wigwam
Tried it today and it works great. Shot hanloads and 165 Remington core lokt factory loads. Didn't try the nosler trophy grade.

Re: 7600 lock up issue

PostPosted: Sat Aug 11, 2018 8:09 am
by mauser9
Good to hear! Glad your solution works. In a way I wish I would have ordered a Model Six or 7600 but that ship has long sailed. Waiting for my Model Four to be a collectors item. Ha Ha

Re: 7600 lock up issue

PostPosted: Mon Aug 13, 2018 8:48 pm
by Wigwam
Compared primers from casings fired with 7600 bolt and the ones with the bolt from the old 7400 . Most of the 7600 ones are slightly cratered. All of these were lower pressure hanloads 3030 level or bit more. I use CCI primers which are usually hard. I've never cratered one that I can remember. The casings used with the 7400 replacement bolt looked normal. I compared bolt faces and used a drill bit that just fit in the ruined 7600 bolt, the bit doesn't come close to fitting in the 7400 pin hole. The 7400 bolt is from an older rifle having the original metal magazine. The 7600 has the plastic bottom magazine. Maybe an oversized pin hole due to quality control in the newer rifle. I'm installing a heavy Wolfe hammer spring just in case but pretty sure it's the pin hole size.

Re: 7600 lock up issue

PostPosted: Sat Aug 18, 2018 10:20 am
by Wigwam
Gun has digested 50 rounds including some 220 gr nosler partition loads. Works great.

Re: 7600 lock up issue

PostPosted: Sun May 05, 2019 3:20 pm
by Hummer70
I have had issues with cratered primers with the outside of the primer still nice and rounded thus it is correctly termed as reverse primer flow. Reverse primer flow occurs when the striker does not have enough sustained energy to hold the indent into the primer on firing and the pressure rises and pushes back on the striker nose and wants to flow into the striker opening.

There seems to be a issue with my 7600 in 270 with reverse flow. When I get time I am going to replace the striker spring and see if that cures the problem. On the 760s I never saw such occur. I have seen 760s with no rifling three inches in front of chamber. They were cycled out of the FBI Quantico Range circa 1980 and sent to FLETC for destruction. That was when I looked at the barrels and could not believe how much they had been fired.