30-30 reloads - primer back out


August 29, 2008, 06:58 PM
I've been noticing that with both factory ammunition and my reloads some of the primers are backing out slightly upon firing.
On average, the primers seem to be backing out somewhere around .006 to .008 inches according to the best figures I could come up with.
At first, I noticed this with handloads and thought that it was probably because I wasn't loading hot enough to get enough pressure to push the primer back in after initial expansion, but now that I see it with factory loads I'm wondering if it might not have something to do with headspace.
BTW - I tested a primer only and upon firing and it also backed out .007 inches.
Function on both my reloads and factory Remington 170 grain and Federal 150 grain ammo is fine and there are no signs of anything strange going on with my casings and no bulges showing up anywhere.
Also, I've noticed variation in the thickness of the rims, which would seem to affect headspace as well.

Does anyone have any experience or knowledge about this?
If there's any reason to think my gun is unsafe I'll have to either invest in a set of headspace gauges or have it checked out.

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Larry E
August 29, 2008, 07:43 PM
The pressures aren't high enough to push the case back to the bolt face which is what makes the primer and case head level after firing. It's just an indication of low (safe?) pressures for a .30-30 lever gun.

August 29, 2008, 07:58 PM
That's kind of what I was thinking too. I've seen it in other lever action 30-30's but I still figured I should check into it.

I really don't want to blow myself up.


August 29, 2008, 08:01 PM
whats your charge. powder bullet primer. what are you using then whats your cartridge overall length.

August 29, 2008, 08:02 PM
This is jostling an old memory in my brainmass. Are you shooting from a Winchester 94?

August 29, 2008, 08:04 PM
we need more info.

August 29, 2008, 08:26 PM
I would check the headspace to be on the safe side.


August 29, 2008, 08:26 PM
Marlin 336, I don't know how old it is but it's a pre-safety model.
I don't remember the OAL of the round but it's a Hornady 170 grain Interlock in a Federal casing. Charge is 33 grains of Winchester 760 with a Win standard LR primer. The bullet is loaded and crimped at the cannelure.
I don't have any loaded rounds right now but my dummy round for this ammo is 2.54 OAL.
Also, I'm getting the same thing with the Remington and Federal Factory loads and I've been seeing the same thing with the primers since I started loading for this rifle. As I said, at first I was sure it was low pressure. Not so sure about that now.

August 29, 2008, 08:57 PM
That's not the best powder to use but it works. It's a little too slow burning to generate optimum velocity and pressures. I would guess that you have a small headspace problem but not a dangerous situation. The fact that just a primer alone backed out would indicate to me that you have some free space to the bolt face. The usual difference between a go gage and a no-go gage is about .006 with another .004 difference to a field gage. The fact that you notice some rim thickness differences just adds to the problem.


August 29, 2008, 09:01 PM
I remember now. I had the same issue with a Win 94, but with no signs of cratering, too much HS or overpressure. Apparently this is something that just happens with certain leverguns. I remember I had a thread on this topic on the levergun forum a few years ago.

August 29, 2008, 09:10 PM
I know Win 760 isn't ideal but I figured it would be OK for playing around for reloading. I'll probably switch to 748.

I don't see any signs of cratering or anything else strange going on with the brass. No strange wear or shiney spots or bulges or anything that indicates that anything strange is going on with my brass.
The strange thing is that this is the same gun that I couldn't get reloading dies for. It took three tries to get dies that adequately resize my fired brass - I'd think that sloppy headspace would mean that it would be more tolerant of cases what weren't fully sized.
Anyhow, there also isn't any evidence of any gas leaking around the primer.
The primers are backed out just enough to be able to feel it with your finger or to just barely see the difference.
I'm thinking I'm going to get it into a smith next week to have the headspace checked just to be sure.
I wouldn't be surpised if it's messed up though - it's my luck.

August 29, 2008, 10:27 PM
748 or H4895 are very good powders to use.
i just got finished loading 100 rounds of 30-30 as we speak. used 748 as im out of h4895

The Bushmaster
August 30, 2008, 10:01 AM
NO no no people...His problem is that his chamber is a bit on the long side and he needs to move the case shoulder forward just a bit. If he (goon) is getting an .008" primer backout then take a .008 to .010" feeler gauge and set your resizing/decapping die off the shell holder by that much and try it again. If you still have primer backout increase the amount a little at a time until it stops. (My 60 year old Mod 94 requires .030" off the shell holder). You will be fire forming the case to fit your chamber. Be careful not to move the shoulder too far forward or you will have hard chambering. That, by the way, will be your indicator you need to move the shoulder back just a bit.

The .30-30 headspaces on the rim, but it also needs to "fill" the chamber or you have the problem you are experiencing. Therefore you want to head space a bit on the shoulder to help push the chambered round back against the bolt face. I have not had any of my primers back out for the last 20 years and I have had this Winchester for the last 48 years...

Try it ...It works...By the way...I use 32 grains of W-748 under a 170 grain Speer FNSP. Very accurate in my "Ol' Jack Handle" I might add...

August 30, 2008, 10:21 AM
You have excessive headspace. Do what bushmaster said, But use a faster burning powder and stay away from a maximum load. The Win 760 does not build a lot of pressure at light charge weights.

August 30, 2008, 10:59 AM
The .30-30 headspaces on the rim, but it also needs to "fill" the chamber or you have the problem you are experiencing. Therefore you want to head space a bit on the shoulder to help push the chambered round back against the bolt face.

Brass will last longer also.

This is a common issue with reloading any bottlenecked case that headspace on a rim or belt.

Reloading was NOT a consideration for these cases.

Set the die for a minimum (a few thousandths) of shoulder bump when resizing.
You want just enough to allow for easy chambering in your rifle.

August 30, 2008, 12:36 PM
For reloads, I'm not sure if I can do anything about it.
I have my dies adjusted as tight as they'll go right now just to get my brass to chamber. This is the same rifle I had trouble getting the brass sized for. It took me three sets of RCBS dies to get something that will push the shoulder back far enough for brass to chamber in my rifle.

Different question, but what is involved in fixing the headspace?
Rebarrel or can something be done by maybe swapping the bolt?

August 30, 2008, 01:36 PM
your rifle needs to go to the gunsmith or better yet, ship it to the factory service center http://www.marlinfirearms.com/customersupport/repairs.asp

The Bushmaster
August 30, 2008, 01:56 PM
Yer kidding...I agree with 243winxb. You have something wrong. Manufacturers tend to give plenty of room for various cartridges and their tolerences are loosely defined. If you have primers backing out the case head is not meeting the bolt face upon firing. .30-30 cases tend to grip the chamber wall quite well as was stated above, low pressure round. Hence the primer backing out. If you are just seeing a few thousands of backout I really wouldn't worry about it as long as the rounds are accurate. In my 60 year old worn chamber (.030"), to me, was a bit much. What I posted above solved the problem, but it sounds like you have a chamber dimention problem also...

Loading hard...Are you sure you are not just feeling the extracter riding over the case rim? To some this might feel like a hard chambering...Insert the loaded round into the chamber by hand and see if the rim is making contact with the chamber mouth. Then close the bolt and see if it feels hard to close. That would be the extracter engaging the extraction rim of the case...

August 30, 2008, 02:08 PM
I also agree.
Call Marlin and find out your repair options.

I thought from the start when you were having the sizing die problems there were extenuating circumstances with the rifle of some sort.

That there just ain't normal with 30-30 chambers.

As for replacing the bolt, setting back the barrel, gunsmith repair, etc.

You would be far ahead money-wise to trade it off for another one that works right.

It's new owner probably won't be a reloader.


August 30, 2008, 02:28 PM
I would probably be better off to get rid of it but I just got it and I like it.
And I'm sure it's replacement would also have something wrong. Every gun I buy needs fixed. It might not seem logical to anyone else but it makes just as much sense to me to get this one fixed and just keep it and like it.
I'm planning to contact Marlin next week. If I have to get it rebarreled maybe I'll see if they have any 16" barrels around from their 336 Spikehorns that they could put on it.

Bushmaster - it's the chamber. I had a thread on this a couple weeks ago and it's definitely something going on with the shoulder of casings. I did get my brass sized to the point where it's chambering smoothly.

August 30, 2008, 02:39 PM
See, that's the part that don't make any sense.

If you are headspacing on the shoulder (With the tight dies) instead of the rim, there can't be any excess headspace leaving room for the primers to back out.

The whole thing is a puzzlement!


August 30, 2008, 02:54 PM
I disagree that this is a serious headspacing problem. Excess headspace with rimmed rounds causes cratering, blown primers and incipient tears in the brass above the rim. I've seen it on some old Mosins, and believe me it's a heck of a lot more dramatic than just having the primer back out a tiny bit. You can check one way or another by having the headspace checked with a no-go and a field.

The Bushmaster
August 30, 2008, 05:25 PM

The headspacing on the shoulder to solve primers from backing out in Winchester mod 94 due to a longer chamber was taught to me by a gunsmith. Mine were backing out .030". By moving the shoulder forward I solved my primer backout problem.

It does seem that he has another problem besides the small primer backing out.

August 30, 2008, 05:26 PM
Yep, it's a tricky one.
With my dies adjusted any looser than they are now I start to get trouble chambering. They won't go any tighter than they are right now either so it's a good thing I finally got the cases sized far enough.
I'd also think that since the 30-30 headspaces on the rim, the primer shouldn't back out any no matter what.
Correct me if I'm wrong, but there should only be the tiniest amount of space between the rim and the bolt face with the action closed, shouldn't there?

Is it possible that I have a tight chamber and loose headspace?

Vern Humphrey
August 30, 2008, 05:36 PM
Hornady 170 grain Interlock in a Federal casing. Charge is 33 grains of Winchester 760 with a Win standard LR primer
This load is below the recommended starting load, which is about 35.0 grains according to most of my reloading manuals.

August 30, 2008, 09:16 PM
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.

August 30, 2008, 10:34 PM
http://www.surplusrifle.com/shooting/headspace/index.asp There has to be some clearance for different rim thickness, how much i dont know on a rimmed case. On a bottle neck case its around .005" I would guess you have a headspace or chamber problem or both.

August 31, 2008, 11:16 AM
http://www.thefiringline.com/forums/showthread.php?p=2156799 Read post starting with #12. Could your extractor be keeping the rim from locking into your bold face? Have you had any extractor/ejection problems? http://www.marlinfirearms.com/pdfs/manuals/MFC_Centerfire.pdf

August 31, 2008, 11:32 AM
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?

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.

August 31, 2008, 11:54 AM
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.


August 31, 2008, 12:33 PM
I'll agree with RC. Give the chamber a good scrubbing and try a faster powder.

The Bushmaster
August 31, 2008, 12:47 PM
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...

August 31, 2008, 12:55 PM
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.

August 31, 2008, 01:11 PM
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.)


August 31, 2008, 01:58 PM
Very interesting thread got to keep an eye on this on. Good stuff RC


August 31, 2008, 02:35 PM
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?

August 31, 2008, 02:37 PM
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.

August 31, 2008, 03:30 PM
You think that would work if I do it by hand and and take it real easy?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.


September 2, 2008, 05:27 PM
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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