Suddenly my cartridges won't chamber...

[Hooda Thunkit]

So, I'm loading for my trusty Finnish Sako M39, a rifle I have fired, quite literally, thousands of rounds through.

I'm loading some used (but new to me) Lapua brass with the tried and true Lee C312.185.1R, sized to 312. The powder charge is immaterial.

The rounds are very difficult to chamber. I can push the bolt closed, but this isn't right. I need to check it out.

Back in the reloading room, I do some measuring. OAL is fine. Brass length is fine, even .015" under allowable.

Maybe the brass is too thick at the neck? I measure with a tube mic, right at . 311/. 312. Loaded cartridge neck diameter spec is .336".
A .312 bullet plus the .011 neck wall (twice): 011 + 312 + 011 is 334", well within specs. Even a 312" neck thickness will just get in under spec (336).

Quick check of SAMMI, chamber specs allow .338" at the neck. It should fit. I've fired many thousands of this exact load through this rifle, albeit with different brass.

I sit and ponder this over a cuppa. Hmmm. Thousands and thousands of rounds...

I screw a brass brush for 38 Spl on a section of brass cleaning rod, chuck it in a drill. Run it in the chamber neck for a couple seconds. Mop it with a fat patch dipped in Eds Red, spin the brush another couple seconds. Repeat.
Replace the brush with a .410 barrel mop, spin that in there.

Cartridges chamber easily now. When WAS the last time I cleaned the chamber?

 

[JmacD]

Btdt! In my case it was a 308 after a difficult pursuit of a whitetail into a bunch of cattails and cornfields. That junk gets in places you can’t imagine. Hence the bolt stuck. And nothing would chamber…

 

[GeoDudeFlorida]

So, I'm loading for my trusty Finnish Sako M39, a rifle I have fired, quite literally, thousands of rounds through.

I'm loading some used (but new to me) Lapua brass with the tried and true Lee C312.185.1R, sized to 312. The powder charge is immaterial.

The rounds are very difficult to chamber. I can push the bolt closed, but this isn't right. I need to check it out.

Back in the reloading room, I do some measuring. OAL is fine. Brass length is fine, even .015" under allowable.

Maybe the brass is too thick at the neck? I measure with a tube mic, right at . 311/. 312. Loaded cartridge neck diameter spec is .336".
A .312 bullet plus the .011 neck wall (twice): 011 + 312 + 011 is 334", well within specs. Even a 312" neck thickness will just get in under spec (336).

Quick check of SAMMI, chamber specs allow .338" at the neck. It should fit. I've fired many thousands of this exact load through this rifle, albeit with different brass.

I sit and ponder this over a cuppa. Hmmm. Thousands and thousands of rounds...

I screw a brass brush for 38 Spl on a section of brass cleaning rod, chuck it in a drill. Run it in the chamber neck for a couple seconds. Mop it with a fat patch dipped in Eds Red, spin the brush another couple seconds. Repeat.
Replace the brush with a .410 barrel mop, spin that in there.

Cartridges chamber easily now. When WAS the last time I cleaned the chamber?

That kind of thing could NEVER happen to me.

I really like 28ga and .410 shotgun barrel bronze brushes for cleaning bottleneck chambers. I use Hoppe’s and Shooter’s Choice usually but for cleaning a chamber I prefer Ballistol first followed by Sweets 7.62 then finish it off with Hoppe’s and a light machine oil.

 

[JmacD]

That kind of thing could NEVER happen to me.

I really like 28ga and .410 shotgun barrel bronze brushes for cleaning bottleneck chambers. I use Hoppe’s and Shooter’s Choice usually but for cleaning a chamber I prefer Ballistol first followed by Sweets 7.62 then finish it off with Hoppe’s and a light machine oil.

I thought shotgun brushes etc were my own “brilliant” idea. HahahahahHA. I cleaned up a very old sporterized 06 once that had so much built up that I declare you could have measured it with a tape measure! It was a mess! The best one I found was an old savage 270. It didn’t have a bottom drop mag. There was some little seeds down in the bottom from busting brush etc… you could see where one of them had started to get a sprout out of it. No, not growing or taking root just sprouting.

 

[bigpower491]

I had that problem with a 91/30. Apparently hours of soaking and scrubbing with mineral spirits when I first got it home wasnt enough to get all the cosmoline out.
I still get a little here and there after an extended session with it. It's the nasty gift that keeps on giving, and those Russians at the arsenal sure weren't shy with packing it on there

 

[Hooda Thunkit]

I had that problem with a 91/30. Apparently hours of soaking and scrubbing with mineral spirits when I first got it home wasnt enough to get all the cosmoline out.
I still get a little here and there after an extended session with it. It's the nasty gift that keeps on giving, and those Russians at the arsenal sure weren't shy with packing it on there

I think the Ruskies applied cosmoline the same way Henry Ford applied paint to Model T autos: just dip it in a vat for X amount of time, pull it out and let it drip for a while.
Done.

Although, I think my problem was carbon. Lots and lots of carbon. A few thousand rounds worth. I don't recall ever scrubbing the neck of the chamber, at least for several years.

 

[Varminterror]

Head diameter of the fired brass?

 

[BW460]

If the chamber is clean, do you need to set the necks back?