Abnormal case stretching?

[esoxmas]

I have been reloading for several years, kind of at the hobby level. I can turn out some great loads for my '06 and keep my family supplied with hunting ammo. I am a careful guy and have had no problems over the years and would like to keep that way.

My question is this: I seem to be experiencing excessive case stretching. My loads are not powerhouses, Nosler 150 gr. Ballistic Tips over 56.5 gr. IMR 4350. Nice performing loads for what I want without pushing limits or getting all beat up. I make an initial trim on new/once fired brass to 4.484". Often times after one loading these cases have stretched .008-.010", enough to make me want to trim them again.

I have read where most folks can get 3-4 reloadings before having to trim. Since I have a large supply of brass I just keep trimming and tossing after the third trim, but I sure would like to cut down on the labor at every load session. Am I doing something wrong? My Winchester brass seems to be the worst offender, but practically any make will stretch more than I expect on the first firing.

Thoughts........... ideas? My first time here, hoping someone may be able to steer me right. Thanks for your consideration.........

/mike

[Mark whiz]

Is the stretching evident when fired from ALL of the rifles those rounds are fired out of or is it just related to one or two specific firearms?

I do know that semi-auto rifles like BARs & Garands DEFINITELY will work brass very hard. Also if a rifle has excessive headspace (or if the brass is sized down too far), the cases will expand more than if the chamber/case fit was tighter.

[esoxmas]

Biggest offender seems to be my 20 yr. old Ruger M77. Shouldn't be a headspace problem as it has only seen perhaps 40-50 rds. annually. Very few of these have been maximum loads. Maybe it's just chambered a little long to begin with?

/mike

[DM]

Do you have your sizer die ajusted properly???? "If" your pushing the shoulder back every time you size the case, it will cause the case to stretch more than normal.

Drilling Man

[Mark whiz]

I'm with DM..............

It may well be that your dies is screwed in a little too far and your pushing the necks back a little far...............which would have the same affect on the brass as excessive headspacing of the chamber. A RCBS precision mic would tell you exactly where your cases are.................I rely on mine for loading ammo for my M1A - as they can be explosive if the ammo isn't right for the headspacing.

[esoxmas]

OK, This may be where I am having problems. My understanding, from the literature I have with my dies, is to screw in just far enough to contact the shell holder at full stroke. I have been reluctant to experiment increasing that distance for fear that I will create difficult chambering rounds. Does the case head area expand much, if at all on firing?

Is there a procedure to determine proper adjustment or a tool to assist? Sure do appreciate your help. I've learned more lately online perusing BB's like this one than I have in searching literally volumes of real print. What a terrific resource!

One other thought, I have not been in the habit of lubing the inside of the case necks for resizing and do notice a substantial resistance on the return stroke. Could that dragging expander cause that kind of stretch?

/mike

[Mark whiz]

By all means, follow your die manufacturer's instructions....................but realize, that is a "general" setting that can and might NEED to be optimized in your case. Screwing the die in further will set the neck further down, shortening the case and increasing it's headspacing. Since you haven't done that, it's unlikely that the case neck is set-back too much then on your rounds.

The RCBS Precision Mic is a VERY nifty tool for adjusting your dies to give you the exact length you want for any particular caliber. I do recommend it to anyone trying to maximize their ammo's accuracy, or if they are having problems like you are

Upon firing, the entire case will expand somewhat, but on a bolt gun - the head expansion has a chance to retract some before the case is withdrawn..........unlike a Semi-auto which rips them right out of the chamber. That's why Semi's are rougher on brass and why they have to be full-length resized in order to chamber. I'm assuming that you are full-length resizing. If so, you might try to just neck size your cases for that Ruger - that will greatly cut down on the stretching and possibly make more accurate ammo to boot. But for guaranteed feeding, neck-sized cases need to be gun specific - in other words cases fired in your Ruger & then neck-sized should not then be fired out of a different rifle.

Lubing the inside of the neck usually isn't recommended by most people. Personally, I lube my cases with Imperial Die wax on the outside and necks I stick into a pile of Motor Mica - that way both the insides & outsides of the neck have a dusting of lube on them that won't contaminate the powder charge that is to follow.

[MShort]

I've been loading my '06 with very similar loads for years. I do trim every time so I'm not sure about the 4-6 reloads between trimmings. I've also FL resized forever in my '06 - a Ruger77 MKII. For the last couple of years these same reloads have gone into a Browning A-bolt. I had to rework the load slightly to accomodate a shorter throat in the browning. Personally I've never seen any reason to do other than FL resize - case life seems to be something on the order of 10-15 reloads.

Some things I do believe to be true.

New cases stretch more for a while but seem to settle down after about about 3-4 times. Trimming seems to show that they stretch differently in the two guns I shoot them in but not much.

Cases from my M1 Garand definitely strech more but I don't shoot the same load or batches of brass in it.

The partial sizing that the others recommend will most certainly reduce stretch and prolong case life. It may or may not improve accuracy. This has only been significant in my .22 Hornet.