30-30 reloads - primer back out

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In my reloading manuals the loads start at about 31 grains and run to about 35 for Winchester 760 with a 170 grain bullet.
My Lee manual lists 33.6 as the max for a 170 grain jacketed bullet. From my manuals, I'm running just about middle ground with this load.

But aside from that, this isn't a rimless round.
With rimless rounds you get primers backing out if the pressure is too low but with a rimmed round, shouldn't the face of the bolt be close enough that the primers can't back out regardless of how low the pressures are?
Also, this is happening with Federal and Remington factory ammo too, not just my reloads.
I'd be the first to suspect that I had something out of whack with my handloads but I doubt that two different manufacturers would screw up their ammo enough to get primers backing out.

Last, I did a little checking with my rifle and some aluminum foil. It is .001 inches thick. I found a casing with a rim thickness of .058 and added aluminum shims until I started getting tight chambering. I got that with six layers of foil, which worked out to .064 acording to both my math and my calipers. It's also just about in line with my measurements of how much my primers are backing out - .006 to .008 inches.
I'm not sure what that means and I know it's not at all scientific.

I'm also thinking I might see what the store I bought it from might do for me since I'm sure this had to exist before I bought it. Hopefully they'll help me out on this.
 
With rimless rounds you get primers backing out if the pressure is too low but with a rimmed round, shouldn't the face of the bolt be close enough that the primers can't back out regardless of how low the pressures are?
Click to expand...

No, even a rimmed round has the same headspace clearance issues as a round that headspaces on the shoulder.

There is a min and max established by SAAMI for the chamber.
 
SAAMI Maximum 30-30 rim thickness is .063".

Minimum headspace is .063"
Maximum headspace is .067"

It sounds like you are right on the money at .064". Can't get much better then that.

However your case rims are .005" under max.

About the only thing I can think of now is a very rough chamber.
Maybe the case is getting such a good grip on the chamber wall it isn't slipping back and re-seating the primer.
Seems very unlikely it wouldn't just stretch, but apparently it isn't.

I'm still thinking the medium load of slow burning 760 powder might be the culprit.
Like to see you bump it up to max, or try a stiff charge of 748, or IMR-3031.

rcmodel
 
I'll agree with RC. Give the chamber a good scrubbing and try a faster powder.
 
rcmodel...I use W-748 and I had the same problem years ago. And what you are saying about the chamber and the case not moving back to reseat the primer is correct. And above is how you solve that problem. If he is experiencing just .005 to .006" of primer setback, I think I would just ignore it and solve his chamber problem first. Then see where he's at and go from there...
 
OK.
I'll check the chamber and clean it up really well. I haven't worried a whole lot about it other than the regular cleaning because I haven't had any problems with extraction or ejection but I'll take a close look.

I'll also try a different powder after I get the headspace checked by a gunsmith. Since I have doubts about it right now I don't want to load it up with a heavier charge of faster burning powder and get myself killed.

But if it's the powder I'm using, how come I'm getting the same thing with factory ammunition?

I also didn't know that rimmed cartridges were supposed to have space between the bolt face and the rear of the cartridge, but now that I know that I'm a little less worried.
A rough or dirty chamber may be the culprit. I had trouble getting my brass resized enough to chamber smoothly so maybe that's why.
 
Pull the bolt out.

Then take some 0000 (Extra Fine) Steel Wool wound around a cleaning rod tip or slotted wood dowel rod, and chuck it up in a drill, add some solvent, and give the chamber fits for awhile.

Whatever is in there won't be when you get done.
(No, it can't hurt a thing as long as you stay out of the rifling.)

rcmodel
 
RC - I don't have any steel wool but I did just give the chamber a good cleaning with this really strong solvent I have called "parts buster".
It's enough to liquify cosmoline so I figured it would take out any gunk in the chamber.
Now I can see some very faint circular tool marks that run the whole way around the chamber for as much of the chamber as I can see.
I'm thinking that these might be my problem.

Makes sense on all counts -
- My rifle "passes" with my homemade bubba headspace gauge. It's not scientific but I know the rifle postively won't close on a thickness of more than .066 total. It chambers very hard on .065 and seems to go smoothly on .064. I still need this verified by someone with the right tools but it's enough to convince me that headspace probably isn't my problem, especially now that I know a rimmed round also needs a little space.
- The tooling marks could be just enough to keep my brass from letting go of the chamber walls the way they should. They don't interfere with function in any way so they probably went unnoticed by the factory during QC and by the original owner. I only noticed the problem because I was watching the primers while I was working on reloads.
- The tooling marks could also explain the headaches I had with getting reloading dies to resize my brass far enough.

I don't have any steel wool but I do have some 400 grit sandpaper that I could make a "patch" out of and run back and forth around the inside of the chamber. I've done this before with a trim die that had some tooling marks in it and it worked pretty well for smoothing them out.

You think that would work if I do it by hand and and take it real easy?
 
The only way to be sure about the headspace is to get the gauges or have a smith do it with a no-go and a field. It's an extremely easy procedure. However with no signs such as cratering, piercing, or incipient case tears above the rim I very much doubt you're looking at a true headspacing problem. You can also have the smith smooth up the chamber. I would NOT suggest doing that unless you have the proper tools and some experience. You can really make things worse if you're not careful.
 
You think that would work if I do it by hand and and take it real easy?
Click to expand...
Black 400 Wet or Dry paper? Yes.

Use plenty of oil to keep the paper from loading up and scratching it more.

Use in & out movements, not round & round.

Sounds to me like Marlins finish reamer was loaded up with chips, or else chipped itself.


BTW: My belted Mag headspace guage is a .220" "Go" button the size & depth of the belt. Steel .003" shim-stock is added to the bolt face to make a "Max" and .005" to make a "No Go".

The only thing wrong with your aluminum foil method is aluminum foil.

Steel shim-stock won't deform and give false readings.

rcmodel
 
So anyway...
I took the Marlin into see a local gunsmith today. It wouldn't close on a No-go gauge. He also looked at my fired brass and confirmed that there aren't any signs of anything strange going on with pressure or headspace.
So, he told me to go ahead and shoot it and not worry about it. He also told me that he's seen this before in many lever actions and also in some other types of rifles. It's apparently something that just happens sometimes. The light tool marks might have something to do with it but over on the levergun forum there are reports of this with other rifles too, especially Winchester 94's. I wonder if it's got something to do with the wedge shape of the 30-30. Maybe it expands out instead of back... ?
I'm relieved because I really like the rifle and it wouldn't make financial sense to put much money into getting it fixed. I would have probably had to get rid of it and get another. But now I can shoot my rifle without worry.

I think I'll follow Cosmoline's advice and not try polishing the chamber on my own because it does seem like something that I could screw up pretty easily.
Actually, I don't think I'll worry about the chamber at all. Chambering is smooth with the dies I have, it's fine with factory ammo, and I've never had any extraction or ejection problem with it.
I figure if it's not causing any problems, it's not a problem.
So unless I start having problems with it, I'm just going to leave my rifle alone and enjoy it.

Thanks for all the advice on this one guys.
 
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