*Updated* #22 - M77 Mark 2 7 mag Fired cases stick in chamber

[1894-44]

I have a stainless 7mm Mag that belongs to a friend of mine. I am going to try to see if I can figure out what is going on with it. He says ever since he's had it after firing a round, the case gets stuck in the chamber and he has to drive it out with a rod. It will extract the case only if it's unfired.
Is there a way to check the chamber to see if it is milled to the correct size.

Thank you!

 

[hittman]

Call Ruger.
Welcome to the forum.

Wonder if he’s shooting the correct ammo or if gun is mis-marked.

 

[Mobuck]

^^^Yeah, need more details.

 

[1894-44]

Call Ruger.
Welcome to the forum.

Wonder if he's shooting the correct ammo or if gun is mis-marked.

^^^Yeah, need more details.

The rounds chamber fine & fire. Extraction is fine on an unfired round. I haven't checked it out myself yet.
It doesn't matter if they are hand loads or quality factory loads.

 

[hittman]

Pics?
Marks on the brass?

 

[1894-44]

I'll use some dykem on a round, see how it comes out & post it afterwards. I will probably chamber & extract one then mark another to fire & check it also.

 

[Mobuck]

Need to see base of fired round especially the primer. Look for striations on body of fired brass.
Fired brass is stuck in chamber, does the extractor slip off the rim while trying to extract?
Several possible issues/probable causes. Wealth of wisdom on this forum. ;)

 

[Sam Summey]

A "look see" with a bore scope should give a proper assessment. I expect the problem is rough chamber from an insufficient lubed dull chambering reamer. Last week I received an 243 American back from NH that had had visible course scratches in the chamber. The report said "polished the chamber and replaced the bolt. The replacement bolt had "brown patina" on the body. The customer commented on the polish of the bolt (I did it, I couldn't stand the "patina"). I test fired the rifle myself both before and after receipt from the factory. Sticking was verified before, not sticking after.

 

[1894-44]

Need to see base of fired round especially the primer. Look for striations on body of fired brass.
Fired brass is stuck in chamber, does the extractor slip off the rim while trying to extract?
Several possible issues/probable causes. Wealth of wisdom on this forum. ;)

A "look see" with a bore scope should give a proper assessment. I expect the problem is rough chamber from an insufficient lubed dull chambering reamer. Last week I received an 243 American back from NH that had had visible course scratches in the chamber. The report said "polished the chamber and replaced the bolt. The replacement bolt had "brown patina" on the body. The customer commented on the polish of the bolt (I did it, I couldn't stand the "patina"). I test fired the rifle myself both before and after receipt from the factory. Sticking was verified before, not sticking after.

I just spoke to the owner of the rifle to find out some more information. He said that when you lift the bolt after firing a round it would open with no problem like there was not a case in the chamber. A light tap from a cleaning rod would remove the stuck case. I am going to check the chamber and the extractor before testing. I will post info afterwards.
Thanks guys!

 

[kmoore]

Look at the fired case and the unfired. Betting they changed shape. As in wrong 7mm ammo. If using the correct ammo would led me to believe a problem with the chamber. What problem? I would need to see it. How many different 7 mm mags type are out there? For sure Remington and Weatherby likely others.

 

[1894-44]

Look at the fired case and the unfired. Betting they changed shape. As in wrong 7mm ammo. If using the correct ammo would led me to believe a problem with the chamber. What problem? I would need to see it. How many different 7 mm mags type are out there? For sure Remington and Weatherby likely others.

Pics?
Marks on the brass?

Here are the pictures of the unfired case & a fired case with layout dye. There were some scratches from feeding out of the hinged plate mag of course. Also you can see some places where the dye rubbed off. The worst looking areas I saw were forward of the belt of the fired case.

It is a 7mm Rem mag & correct ammo. The fired case extracted with the bolt by tapping the handle with a rubber mallet. It would not open by hand. I cleaned the bore and chamber very well & could see no marred places in the chamber, just smooth and shiny.

The case measurements are listed (unfired / fired)
Belt - .5275 / .5285
Fwd of belt - .5070 / .5095
Body just before shoulder - .4835 / .4915
Neck below the crimp .3065 / .3145

Primer was normal, no signs of overpressure.

 

[kmoore]

Borescope is needed. 1 is chamber to rifling photo. The other was a nice shinny clean bore until the scope looked. Will look up from better chamber photos I have stored somewhere.
Edit: I don't have any photos of chambers handy.

 

[Mobuck]

The 'layout dye' could have affected the opening of the bolt by sort of 'gluing' the case to the chamber but you did confirm that the extractor will pull the case from the chamber. This is different than the comments from the owner that NONE of the fired cases were extracted and ALL required knocking out with a rod.
You might try fitting a round into the bolt face and gently feeding it into the chamber. This would reduce the scraping/scarring resulting from feeding from the magazine.

 

[Mobuck]

What's the chances the owner was feeding the rifle 280 Rem ammo?

 

[1894-44]

None, I confirmed in an earlier post that it is a 7mm Rem Mag & using correct ammo. I don't have a true bore scope, it's an inspection camera. I will post some shots of the chamber shortly.

I spoke with Ruger and they emailed me a shipping label to NH for sending it in to be checked & corrected. Either ream the chamber correctly or re-barrel it.

 

[1894-44]

Here are the shots I got, they're not great but they are the best I could get. The last 2 look odd because I had a bore light at the muzzle. It looks like you can see the rifling around the outer edge of the end of the chamber.

 

[planetcat]

I had this happen on a .300 win mag, but the case would not come out. Crappy brass from cheap eastern block ammo expanded and fused to the chamber after firing. It had to be machined out. I would try different ammo. If it feeds fine before firing, the brass should not expand that much after firing that it has to be pushed out with a rod through the muzzle. The reloaders on here should have some insight on the bad brass theory.

 

[1894-44]

It does this on all the ammo that has been fired from it. Doesn't matter what brand.

 

[gunzo]

Likely a rough chamber just ahead of the belt. But, the rifle could have a tight bore that's raising pressure.

A peek at the primer that's still in a fired case might be a clue.

 

[1894-44]

I've noted all that previously in this post. The primers look normal, no visual problems seen.

 

[gunzo]

Primer looks fine, no indicators of too hi pressure, so that kills the tight bore theory.

Judging from the fired case it looks like the chamber has a rough spot just in front of the belt.

 

[1894-44]

Update on the M77 .308
I sent it to Ruger in NH. They opened up the chamber & polished it. Reworked the bolt, cleaned, test fired rounds & cleaned again before shipping it back. I checked it out, fired several rounds through it & all is well!