I have 2 308's one is a Kimber Montanna and the other a win mod 100.

I reload for both but recently I have had 2 cases rip in half( 1 inch from head).

One case ripped in half in the resizing die and the other one ripped while extracting it from my Kimber.

Does the small base dies have anything to do with weakining the cases in this area.

Loads too hot or headspace problem. If it happened in both guns, over charged.
Pete

Are you segregating the cases by which rifle they are fired in? If not, you are probably creating excessive headspace when sizing your brass. Doubtful that both chambers are identical in length.

No I am not segregating the cases, should I be?

Should I be full lenght resizing with small base dies. I know I need to for the auto but do I need standard dies for the bolt?

I do not get other signs of pressure as in flattened primers, loose pockets, hard bolt lift etc.

The load is 47 gr of 4064 with a 210 fed and a 150 ballistic tip on top.

Nosler book says 48 gr of 4064 is max.

I doubt your load is the issue. You are simply working your brass more than you need too. At least in the Kimber. When you full length resize you will set the shoulder back. Your chamber(s) more than likely are a touch longer. (all three within standard). The case is moved forward by the firing pin then has to expand (in your case move the head back) to fill the chamber. After a few fires the case gets thin just infront of the head.

To extend the case life most people with seperate the brass and only resize enough to allow chambering in each rifle. This will work the brass the least. In the case of the 100 you might not have a choice and have to full resize to get the head area small enough to chamber. Keep track of your number of reloads. If the head seperates after 4 reloads toss it after 3 or even 2 to be on the safe side. 308 brass is cheap. In the Kimber I would resize the minimum needed to allow chambering some do it with a neck sizer I think the majority simply set the die so that it just touches the shoulder and doesn't set it back. After several loading you might need to bump it back a touch because after each firing the case will more closely fill the chamber and could get tight as you try and close the bolt. Not an issue at the range but would hate to miss the follow up on that record deer.

I have never used a small base die. But would "assume" you could still use it for the Kimber. I use the same die on two different rifles. I just stick a spacer under the nut to lift the die for the one rifle. In your case the Kimber. Or just buy a sizer and use your seater on both.

I'm too lazy to read all the posts so this might have been already covered. The Model 100, I would suspect is the culprit. Most auto-loaders play havoc on brass over a few loadings, especially if you have to full length size. You should buy new brass for both rifles and keep the cases fired in the Model 100 separate from the Kimber. If you are using small base dimension dies, buy a regular sizing die and use it on the Kimber brass and try it on the Model 100 brass. If it works for the Model 100, stop using the SBD die altogether and for sure, do not use it on the Kimber. I would bet that the case head separations will not occur on the Kimber brass and will probably continue on the 100.

Thanks, I am going to order new dies for the Kimber and new brass and keep it all separate.

Appreciate the input fellas.

Ramrod has the answer!

quote:

Originally posted by powerguy:
Thanks, I am going to order new dies for the Kimber and new brass and keep it all separate..

Hey Powerguy, Looks like some excellent responses and a good plan as you go forward.

When I have two or more rifles chambered for the same cartridge, I just have a Die Set for each of them. I guess I could get by with just buying a separate Resizing Die for each, but I also keep, Seating Depth notes and a Test Bullet inside the Die Box to keep an eye on how much the Throat is receeding.

1. I'd recommend you Set-Up and use the new Die Set with the Kimber and use the Small Base Die Set only for the M100.

I also like the M100s, but they can be tough on Cases as has been mentioned above. Since all semi-autos are tough on Cases, I'd also recommend the following:

2. Buy once-fired Military Cases for use in the M100. They are a bit thicker where the Insipient Case Head Separations occur. And as a nice side bonus, they are relatively inexpensive and usually of fine quality.

3. Check in your catalogs or on-line in the "Hoppe's Products" section for a short T-shaped cleaning rod made with a flexible Delrin shaft. You can use it and a 44Mag brush to reach in through the Ejection Port to clean the Chamber.

Since the rifle's bore must be cleaned from the Muzzle, as the brush enters the Chamber, the bristles spring out and thrown all kinds of trash and residue into the chamber. This can't be wiped out by running a patch through, because it won't expand wide enough to wipe it clean. So, access must be made through the Ejection Port.

If the residue and trash is not removed, it will cause the rifle to get "out-of-time" and cause various extraction, ejection and feed failures, plus it causes the Rims to be more severely damaged.

Also, when cleaning the M100, put a Spent Cartridge in the Chamber(with the spent primer still in it) and then do your normal Bore Cleaning. This will trap the majority of the residue/trash inside the spent cartridge. Save it in your Cleaning Kit and use it everytime. But you STILL need to scrub the Chamber clean.

4. You should begin using the old "L-shaped" Feeler Gauge Trick to determine when your cases are exhibiting signs of Insipient Case Head Separations in the M100. Take a stiff wire, like a Paper Clip, and use a set of side-cutters to nip off one end. This creates a small chisel tip.

Now bend that tip 90deg so the extending Leg is about 1/16" long and will act like a small scraper.

After you fire the Cases in the M100, run the Feeler Gauge inside the Case all the way to the bottom and pull it back out slowly. If you "feel" a small groove exactly where the Pressure Ring is located, go on and toss those cases because that is Insipient Case Head Separation. It may break right there during Resizing and hang in the Die or let go on the next firing of the case. Neither of which is any good.

5. I normally DO NOT recommend Loads for anyone, but I would encourage you to use H4895, IMR-4064 or Varget in the M100. And good old Round Nose Bullets do amazingly well in them. Plus the just look right in it.

6. NEVER take the stock off the M100 " until " you obtain one of the NRA Tear Down Manuals that has it listed. It is relatively easy to crack the stock in the "thin" mortise area near the magazine well - if done incorrectly.

And if you deside to disassemble the mechanism, have some good old KY Bourbon in the frig - cooling.

It is a beautiful, complex and amazing design. But it is a nightmare to take apart and reassemble. If you start taking it apart, just do a bit and then reassemble it immediately while noting all the mechanical relationships. Then go a bit deeper and repeat.

Once you do FINALLY get it all back together, it is time to visit the frig!

Best of luck to you.

Thanks guys for the education, I truly appreciate it.

John

quote:

Does the small base dies have anything to do with weakining the cases in this area.

Maybe, but NOT because it is a small-base die. If the cases are developing incipient separations due to over working the brass, it is because you are settiong the case shoulder back when full-length resizing the brass, then it is stretching back every time you fire that case. Repeated stretching & shortening are causing the brass to thin out, then crack just ahead of the web. In addition, the Model 100 may also be working the brass too much. Semi-autos are often pretty rough on brass!

Separate your cases. Don't use the same brass in that nice Kimber that you use in the M 100. Then make sure that you set the FL sizing die out far enough so it does not set the case shoulders back when you size the brass......

I'll bet you could use a regular die (not small-base) for both rifles. I have never had to use a small base die for semi-auto ammo. Regular dies have always worked quite satisfactorily for me regardless of the type of gun.