Author Topic: 308 Case expansion. (Read 714 times)

Bearwolf31 · « **on:** August 01, 2004, 04:42:53 PM »

I have been reloading for my 308 win and have noticed the excessive growth of the case length. I started out with new brass which was sized and came out to around 2.007". I loaded up mid range loads and after firing these the case length was around 2.010 or less. However after resizing the case length is now 2.015 and slightly over, which is at max or exceeds max length. This doesnt seem normal to me to have to trim my cases after every time I fire them?? :?

Also, I have a buddy that reloads for his 300 win mag and the cases are difficult to extract, yet the loads are at min published rates and the bullets are .020"+ off the lands? Whats wrong with this picture? the cases are at max case length or slightly less?

jgalar · « **Reply #1 on:** August 01, 2004, 05:00:02 PM »

You need to neck size your 308s. When you full length size the only way the brass can "flow" during the sizing is up or increasing the length. Your cases will be getting thinner each time, and your cases will not last many fireings. I have cases that have only been necked sized and they have been reloaded and fired at least 20 times. I seldom need to trim them.

Your buddy should trim his cases below maximum length and also check the condition of his chamber.

John Traveler · « **Reply #2 on:** August 01, 2004, 06:37:57 PM »

Cases normally stretch only a couple thousandths on each firing, assuming your loads are not excessive. If your .308 cases are acctually growing some 0.007" on ONE firing, you probably have a bad combination of slightly oversized chamber and slightly undersized FL die.

There is not too much you can do about an oversized chamber, but you can try different sizing dies, or neck sizing only as jgalar suggested.

Difficult extraction can be caused by any one or combination of factors: excessive pressures, soft brass, rough chamber, etc. And YES, excessive case length can build up chamber pressure and cause difficult extraction too.

Leftoverdj · « **Reply #3 on:** August 01, 2004, 09:15:06 PM »

Lee #2 shows the trim-to length at 1.995. This will help some. Size and measure a few cases with the expander ball removed. Excessive drag over the expander will stretch cases. If this test shows a problem, lubing the inside of your case necks will help some more if you are not already doing it. You might also lightly polish your expander ball. Just spin the assembly in an electric drill and press a cloth loaded with a very mild abrasive against it for a minute or so. Old Dutch cleanser works fine for this, but Ajax is too abrasive for my tastes.

Other than that, I agree with the other guys. Either neck size or adjust your full length sizing dies to partially resize the least that will let your cartridge chamber readily.

Catfish · « **Reply #4 on:** August 04, 2004, 06:51:15 AM »

DONOT LUBE THE INSIDE OF YOUR CASES with a lube grease or oil. I neck size only for the majority of the rifles I load for. The best way to lube case necks for neck sizeing only is to use an old box you got bullets in. Fill it about 1/2 full of number 12 shot, if you can`t find 12`s size 9`s will work well for .22 cal. and larger. To the shot add a couple of teaspoons of Mica. If you can`t find Mica graphite works well also, it`s just alittle dirtyer. Shake this up well and just dip your case necks into the box and size. I even use this method when forming brass and take it down 2 steps with 1 dip. Grease will ruin your powder charge, but a small amount of mica won`t.

Bearwolf31 · « **Reply #5 on:** August 04, 2004, 01:40:47 PM »

ive been using the hornady one shot to lube the cases and case necks. Seems like if you use a liberal amount of it then the cases just slip right in the die and out. I figure that the lee case trimmer i have only trims back about 0.005" from max length, sooo at that rate I guess I can just expect to have to trim after each firing, luckily that little lee trimmer makes the whole operation fast.

thanks, for the replies.

ooops. I forgot to mention the loads I am using are 150gr SST's and Speer Hot-Cor's are 46grain and 45.5grains of IMR4064. 47gr is supposedly the max according to my speer 13 manual.

Leftoverdj · « **Reply #6 on:** August 04, 2004, 04:33:27 PM »

Quote from: Catfish

DONOT LUBE THE INSIDE OF YOUR CASES with a lube grease or oil.

Lube grease or oil? Closest I ever heard to that was one crazy who used STP, but he was odd in other ways, too.

Lee case lube is a wax. Lubing the inside of the neck with it don't hurt nothing. I mostly use anhydrous lanolin as case lube. It could cause bridging in small calibers when used in the case mouth, but that's the only problem I know of.

I do believe that before I would trim my cases for every shot, I would shorten the tip of that Lee pilot a bit.

Bearwolf31 · « **Reply #7 on:** August 04, 2004, 05:27:09 PM »

I did happen to take the FL die apart tonite and checked out the expander ball and boy was it rough and in the middle of it was like they put the thing on a lathe and ground into it. A little rough to say the least. Looks like I need to chuck it up and try and polish it up somehow. It must have been training day at rcbs by the looks of the expander ball.

the hornady one shot is great as its superslick yet wipes off later with the greatest of ease.

sgtt · « **Reply #8 on:** August 04, 2004, 07:42:52 PM »

RCBS would probably send you a new one if you called them.

Bearwolf31 · « **Reply #9 on:** August 05, 2004, 03:02:04 AM »

Yeah I may give them a call. They have already replaced the whole die a couple months ago as the previous one was scratching up the cases.

I have been thinking about getting a neck sizing die and think I may look at Redding next.

sgtt · « **Reply #10 on:** August 10, 2004, 07:57:35 PM »

Redding makes great stuff. You might also consider the Lee collet dies. Lee products are either loved or hated.

djl4570 · « **Reply #11 on:** August 11, 2004, 07:02:42 PM »

Quote from: Bearwolf31

I did happen to take the FL die apart tonite and checked out the expander ball and boy was it rough and in the middle of it was like they put the thing on a lathe and ground into it. A little rough to say the least. Looks like I need to chuck it up and try and polish it up somehow.

the hornady one shot is great as its superslick yet wipes off later with the greatest of ease.

I chucked mine in a drill motor and went to work on it with 600g wet dry and spit. Polished out the machine marks and finished with 1500g wet dry. Takes about 10 minutes. The only time I use this die is when sizing new or once fired brass that I purchased.

I bought a Hornady expander but it wouldn't work with the new style of decapping pin my RCBS die uses. The Hornday expander doesn't have a place for little knob on one end of the pin.

For my bolt actions I use a Redding micrometer adjustable bushing neck die and size at most the top .100" of the neck. This is giving me good neck tension and some excellent accuracy. For my M1A's I have been using the RCBS X die and it really does help prevent the kind of extrusion you're describing.