.308 sizing issues

[silicosys4]

I am having problems with a .308 Swedish Mauser.
When resizing once fired 7.62 LC brass with rcbs .308 dies, I have to screw the die down in my rock chucker until it cams over pretty hard against the die. Just a moderate or light cam over wont do it, the bolt won't close when a round is chambered unless I screw the die down to the point that I feel I might be doing damage to my die or press....at the point that I almost can't push the handle fully down from the cam over without putting body weight on it, and the release is hard.

What am I doing wrong? My only other .308 is an FAL which doesn't require nearly as much sizing to chamber reliably.

 

[rodregier]

Chamber dimensions can vary quite a bit, which can determine how much sizing a case needs.

I would guess the chamber on the FAL is looser than for the bolt-action Mauser.

Keep in mind some of the once-fired mil-spec brass can be fired in some pretty loose chambers, which can include GPMG's. Those can be a serious challenge to get resized enough for a tighter chamber. Small base dies is one of the solutions to that issue.

 

[MtnCreek]

You need to figure out where the resistance is coming from. Is it the dia of the body or the length of the case from head to shoulder.

Do you have a tool for measuring case length from head to datum of shoulder?

 

[USSR]

Welcome to the wonderful world of machinegun-fired 7.62x51 brass. The web area of the brass is expanded beyond specs, and a FL die doesn't size far enough down the case to bring it back within specs. Also, by screwing the die down further, while reaching a little further down the brass for sizing, you are at the same time bumping your shoulder back farther and likely shortening the life of the brass. With any once-fired 7.62x51 brass that does not have a headstamp that includes "Match", "NM", or "LR", assume that it is machinegun fired and resize it using a small base die. Then, once you have fired it in your rifle's chambers, you can return to using a regular FL sizing die. Hope that helps.

Don

 

[james layman]

I believe their is a case length difference between military & commercial ammo. Some of my .308 chambers too deep and does not fire. I had to back off on the sizing die to get it to function. I plan to measure the chamber, to get the exact headspace. I'am told the .223 & .556 is also a problem. Suggest you try a different brand of die.

 

[rodregier]

+1 what USSR said.

 

[silicosys4]

Ok that makes sense, most of the brass is just LC, and about half of it resizes with a lot more resistance and comes out of the resizer at upwards of 2.025"+ case length.

 

[TIMC]

I have 2 .308 rifles with really tight chambers and had to buy small base dies to make my resizing issues go away.

On clearance sale right now for a really good price.
http://www.midwayusa.com/product/681255/rcbs-small-base-2-die-set-308-winchester

 

[silicosys4]

Thanks everyone, sb dies are on the way, sounds like that should solve my problems.

Why is it that the machine guns stretch brass so much?

 

[tightgroup tiger]

Small base dies should take care of your problem.

What USSR said. +1

 

[joustin]

The chambers on machine guns are loose to aid in extraction and reliability. More room for error / dirt /fouling etc.

 

[fguffey]

silicoys4, I will start with a question: Have you ever used new, factory, over the counter unfired 308 military ammo in your rifle?

To start with you have an advantage, you have a Rock Chucker that cams over, I have 4, not one of my Rock Chuckers will cam over. There is something about the design that will not allow the ram to go up, turn around and start down again. without lowering the ram.

When sizing cases it is possible to determine of the case had more resistance to sizing than the press can overcome. It is not necessary to remove the case from the press and or chamber the case before deterring if the case was sized before lowering the ram. If the case was was sized to minimum length/fulkl length sized there will not be a gap between the top of the shell holder and bottom of the die.

Terms that have no value, ‘screwing the die down until you think you could be doing damage’. And that part where you are required to put body on the handle. There is an adjustment of the die to the shell holder with contact, after contacting the shell holder with the die there are fraction turns of the die that can be converted to degree and thousandths, from the beginning there was the additional turn of 1/4 = to 90 degree= to .017+ thousandths. I screwed a die down 2 complete turns or .142” when attempting to sixe a case in another reloaders AMMO MASTER PRESS, once the ram was up and locked? the gap between the shell holder and bottom of the die was .017”, what did that mean? The case he was trying to size whipped his press, the case he was trying to size had more resistance to sizing than his press would overcome. He insisted on using Imperial sizing wax/lube or Dillon in a can or bottle. As always I had my stuff but that was not an option.

I am not the fan of abusing a press, problem, you did not check the gap between the shell holder and bottom of the die before lowering the ram. If the die made it to shell holder the press was doing all it could do, removing metal from the top of the shell holder and or bottom of the die would increase the die and shell holder’s ability to size the case.

Then there is the purchase a small base die’, first I determine if I need a small base die, I have small base dies, lots of them, I do not use them because I always find a way to size a case without them. But, if I needed a small base die, I would first use a forming die, the forming die can be used on those tuff to size cases and as always after using a forming die a full length sizing die must be used size to final caliber.

F. Guffey

 

[silicosys4]

^^Actually, after reading through that, none of that makes any sense or was helpful in the least, a lot of it is contradictory, and seemed to be mostly an exercise in snarkiness and self praise. Perhaps someone with a less lofty opinion of themselves and their reloading abilities can translate that into something useful.

Edit: I'd did get one part. I'm not going to grind on my shell holder though, its used in a few of my machines and ruining it for all of them except my single stage is not going to happen, especially since I posted that I have a small base die set on the way.

Thanks to everyone who's chimed in with useful info!

 

[Dthunter]

Lol!

 

[gamestalker]

Actually F. Guffey has provided some very valuable in depth knowledge that has helped me better understand various elements of reloading, so I personally value his in put. He can be some what blunt at times, but I find he is mostly always on target, if you can get past the long winded paragraphs of explanation. He might not have the best bed side manner, but he is very, very knowledgeable, so please try to refrain from making personal attacks on his offer to help, I would hate to see him leave our forum.

To paraphrase some of what F. Guffey said is, when the ram is a full extension, you will almost always find that there is a measurable gap between the shell holder and the die when the brass is being resized, regardless of how much cam over is present. This is due to the fact that the brass did in fact whip the press, I see it with every piece of brass I run into the press. This is where a feeler gauge will identify how much gap applies to various degrees of shoulder set back, head space, bump, what ever term you prefer to apply.

We are all here to offer, and seek advice, best of luck with your issue.

GS

 

[W.E.G.]

sb dies are on the way, sounds like that should solve my problems

Maybe.

Maybe not.

What gage are you using to measure your loaded rounds in the dimension from the base of the case to the shoulder of the case?

If you are not measuring this dimension, anything else you are doing is just guesswork.

 

[Laphroaig]

Maybe.

Maybe not.

I agree. It sounds like your problem is either due to a chamber that is too short, or one that is too tight. A previous poster asked if factory ammo will chamber properly. IMO, if it does, you probably have a tight chamber, and the SB dies will fix your problem.

If your chamber is too short, the SB dies won't help. I've has this problem with 7.5x55 and ground my shell holder 0.005 which helped. I need to go a few thousand's more to totally fix it. If you don't want to alter your shell holder, get another one.

The hard cam-over that you describe probably isn't doing you all that much additional sizing wise and is likely putting a lot of stress on your presses linkage. Fortunately, Rock Chuckers are tough animals.

I've never done this, but I remember hearing that RCBS will regrind dies that don't work in your rifle if you send them a couple of once fired cases. I'd give them a call if the SB dies don't fix your problem. They've always done what is right by me, sometimes going above the call of duty.

Laphroaig

 

[ranger335v]

Put a good layer of case lube on the lower body of your cases and the extra effort should be greatly relieved. The length of a sized case makes no meaningful difference to the sizing effort.

"Cam over", as such, also means nothing - just size your cases until they fit your rifle. Do your usual sizing and, with a case fully inserted inside the die, look to see of a sliver of a gap is between the die and shell holder - if there is, screw the die in and try again, keep it up until the gap disappears. If there is no gap, sand or grind a tad off the bottom of the die and try again; keep it up until the empty sized cases will chamber easily. (It hardly seems logical to "fix" a shell holder to get a too long sizer die to work right.)

A SB die is going to make it more difficult to FL size your cases, not less, but plenty of case lube on the thick part of the cases will make it easy enough.

 

[Laphroaig]

sand or grind a tad off the bottom of the die and try again; keep it up until the empty sized cases will chamber easily. (It hardly seems logical to "fix" a shell holder to get a too long sizer die to work right.)

what's the difference?

 

[xfyrfiter]

The FAL and the bolt gun are two very different animals and as such it takes different diets for each. My AR and my varmint rifle take different loads and as such I only reload rounds for the bolt gun that have been previously been fired in it and I neck size only. The fl sb die I save for AR fodder.

 

[medalguy]

I second this comment. I also have an FAL and it eats just about anything I feed it. The chamber is slightly oversized I think, as are most military chambers, not just MG chambers. Commercial rifles are generally tighter chambered I've found. YMMV.

 

[ranger335v]

Quote: "sand or grind a tad off the bottom of the die and try again; keep it up until the empty sized cases will chamber easily. (It hardly seems logical to "fix" a shell holder to get a too long sizer die to work right.)"

what's the difference?


Difference is that shell holders are supposed to be interchangeable with other dies; that's why the standard deck height is 1/8". If we "fix" a shellholder to correct a die problem we won't have an interchangable die OR shell holder and, used normally with another die, a thinned shell holder could easily result in dangerously increased headspace problems. So, fix the die; it will still be vertically adjustable to match other needs too.

Redding's costly "competion" shell holders would only make this problem worse, those shell holders have HIGHER decks, not lower.

 

[Laphroaig]

I dunno, I'd still buy another $10 shell holder, and customize it for the rifle that has a short chamber. I did one on a belt sander without a lot of effort.

As for grinding down a $35 die, depending on your machine shop capabilities, you could bubba it destroying any resell value. That's some hard stuff. Then you have to readjust said die every time you reload for the other rifle.

Maybe the SB dies will fix the OPs problem, and this will be moot for him.

Laphroaig

 

[MRH]

I'd try modifying a shell holder.

Regarding post #12. Is there something wrong with or a limitation for Imperial Sizing Wax? I've been using it for MANY years without problems.

Mike

 

[rodregier]

Imperial Sizing Wax is often touted as one of the best "purpose made" resizing lubes when applied in the right places. (FWIW).