I have been successfully reloading for my 308 win for the last few months, and my loads have been excellent out to 1000 yards.
I would like to thank everyone for their help and advice and at the same time discuss another issue I am having.
I am using a relatively light load of 43 grains of Varget with 175 grain Sierra's.
Some of my Lapua brass that has been loaded five times is starting to cause the bolt to stick upon ejection. Eight out of the eleven shots I fired with the brass was sticky. I also shot a bunch of other Lapua brass that had been loaded less than 5 times without any problems?
I am wondering what is causing this? There are no cracks in the case and the primer pockets are okay. Before I loaded them I checked to see if there was a donut forming inside the neck but couldn't see any. Although I didn't see a donut in the cases I believe that there could be one forming that is causing the excess pressure, what do you guys think??
Are you experiencing any difficulties chambering the case that have been fired more then 5 times? how are you sizing the cases? Have you measured the muzzle vel to compare new vs old cases? How large are the cases about 1/8" in front of the extractor groove, new vs old?
More info might give light to the problem. I suspect that the chamber is a little large at the base and the cases are growing to fit. After a few firings, the brass is work hardening and not releasing from the chamber walls. headspace will also play a role in this. Is this a factory rifle?
Answers to the questions above will help solve your problem. if you can, try some other brass like Fed Gold medal, and see if you have the same problem.
My rifle is a Robar SR90 with a custom chamber, not tight necked though.
I just happened to full length size all my brass before I fired it this time because I had fired some of it in my friends 308 win, duh, I forgot I did that. My friend has a Robar like mine though. I realize that the chambers aren't exactly the same. However, I don't think that caused the problem because the measurements all look ok?
Here are the measurement I got:
Case Head thickness
new case = .4675
twice fired = .4710
once fired case head = .4705
5-times fired = .4715
Oal of brass (chamber will accomodate 2.04)
new case = 2.0095
3-times fired = 2.01
5-times fired = 2.015
Shoulder Headspace measured with Stoney point gauge. (I zeroed the caliper on the gauge)
New Case = 1.6215
once-fired = 1.623
5-times fired = 1.623
new brass = .015
5-times fired = .0145
Rim thickness measurement
new case = .4695
5-times fired = .4705
Light load for sure,, I shoot 45gr under a 175, but I'm sure my chamber is larger than yours. I get 2700 to 2730fps from a 26" factory tube.
Did the cases cause any sticking after you FL sized them? I generally just neck size and they get tight after 4 or 5 firing. After 6 or 7, they NEED to be FL sized. If you can still open the bolt without forcing it, this may just be normal case expansion.
I did notice that I got unusual expansion on occasion if the bullet was into the lands .
If you don't neck turn, I wouldn't think you'd have a doughnut. As I understand it, that only happens in neck turned brass but I may be FOS on that one, so best to double check.
It was easy to lift the bolt the first 3/4 the way up but the top 1/4 was pretty sticky for a the rounds I'm talking about. I did let the rifle get pretty dirty, fired 60 rounds without any cleaning.
It is a light load for sure I have tried 45 grains with the 175's too without any pressure signs. I got 2770 fps with 45 grains out of my 24" Schneider fluted barrel [img]images/icons/grin.gif[/img] . I decided to use the light 43 grain load because accuracy was really good and I am getting 2650 fps which is all I really need. Plus since I am a newby reloader I wanted to take it easy for a while.
If your chamber was clean and dry when you started, 60 rounds should be nothing for a 308 with Varget. I've shot 150+ with no trouble.
If you're just feeling a tight bolt (maybe a slight hanging) for the final 1/4 of the ejection throw,, that doesn't sound like a big problem to me. It's hard to say, not actually being there.
When you have to beat the handle up with the palm of your hand,, it's too tight [img]images/icons/grin.gif[/img] BTDT
2650fps MV for such a light load is GREAT, no need for more speed. I needed to go to 45gr to get these damn Lapua cases shooting for me. I had to turn the wick up to group under 1moa at 100/200 yards,, but the extra velocity has helped at 1K. I've had my best luck with Winchester brass and 44.2gr Varget, but my misses bought me 200 Lapua cases per my request for Christmas last year,, so they WILL be used.