I recently loaded seventy rounds of .300 WSM using 180 grain partitions. I used 100% once fired brass and all the primers were seated with some but no where near the usual pressure. The brass was from three different rifles and all of them had the same "loose" fit of the primers.

I also loaded several .325 WSM rounds for the same guy a couple years ago and the same "fit" was noticed there.

It's not to the point that the primers might fall out or cause a problem.....just obviously not the snug fit I'm used to.

If you reload any of the WSM rounds, have you noticed the same loose fit?

Its not just related to WSM cartridges, check the diameter of your primers. I have had some lots of primers that were undersize, and you would get the loose fit in unfired factory new brass. This was not just one lot of brass but several lots and several brands. I eventually measured the primers and found they were undersize. I now take calipers and measure the primers before I buy. Hope this helps.

The unplated Winchester WLR & WLRM primers that I have measure undersize and fit loose in good primer pockets WSM or not.

There are specific dimensions for primers and these primers are out of spec.

They can fall out of a primer pocket.

The WSM series factory loads generate pressures well in excess of factory loads for other calibers (which is the only way you can get similar velocities to those yielded by larger cases.) I've experienced sticky bolt lift with a .300 WSM shooting factory loads. When you get sticky bolt lift this means that the case head is expanding; if the case head expands then the primer pocket will expand along with it. Excessive pressure from the initial firing of a factory load may or may not be your problem, but it is certainly suspect with WSM's.

The unplated WLR & WLRM primers I have measure undersize.

It's not the primer pockets.

quote:

Originally posted by Savage_99:
The unplated WLR & WLRM primers I have measure undersize.

It's not the primer pockets.

can you tell us what they measure and how you're measuring them and what they are supposed to be?

And BTW.....I was using Remington magnum primers!....not Winchester primers.

do a search on boardreader.com

quote:

Ignored post by Savage_99 posted 27 May 2014 00:08

for the record

It does sound like a pressure issue with the first firing. I have loaded a lot of 6.5WSM made from 270 WSM W-W cases. Having worked these loads up with no published data I was probably on the moderate side of the pressure scale. I was easily matching velocities from the published data on the 264WM and had great case life with very consistent primer tension through many repeated loadings. These cases weren't FC headstamps by chance?

just what stony said. and here i thought you were a genuine 06 guy next thing i know you'll beshooting a blaser

I have shot a blazer before!! It was a 79 model somebody dumped out at the quarries. It was fun until we had all the glass out of it and got used to the sound of the bullets punching through the doors. Those Blasers are reliable. I bet we went through over a 1000 rounds with several different calibres with no malfunctions!

quote:

Originally posted by butchloc:
just what stony said. and here i thought you were a genuine 06 guy next thing i know you'll beshooting a blaser

stony knows his stuff.....and seems the most likely explanation.....and yes.....I'm an "06" kind of guy...and no....Blasers are not in my future.

These are all Winchester cases from once fired factory loads.

The .300 WSM is on a Remington Model 7 that I rebarreled from a .300 RSAUM.....The SAUM ( Remington factory gun and Remington factory loads) was so overpressured that the owner had serious trouble opening the action after firing.

I must say that the .300 WSM also has a slight bit of reluctance to opening as well.....but a far site better than the SAUM combimation.

Remington refused to stand behind this issue as they wanted over $300 to rebarrel it.

It also seems the .300 WSM is simply a short action .30-06 with a 100 FPS advantage.

quote:

It also seems the .300 WSM is simply a short action .30-06 with a 100 FPS advantage.

When loaded to similar pressures that's about right. However, I get 5-down in my '06 magazine and if you're lucky you get 3-down in a WSM magazine. Ideally, it just takes "one", but in a hunting rifle that magazine capacity difference can be significant. I can remember several occasions in which, but for the last round in a 4- or 5-shot magazine, a beautiful trophy animal would likely have been lost.

I notice loose fit with Winchester primers in most of my cases regardless what caliber.In my 300 WSM,I bought some range brass when I first got it.I was amazed at how expanded some of those primer pockets were.Some of those pockets were so loose you could set a primer in it and feel it move with your finger.That had to be some extreme pressure to expand it that much.OK,let me tell you about my rifle,the throat is virtually none existent.I'm usually seating .030 off the lands and loading 3 to 4 grains less than most of the book max loads.To give you an example.I'm loading 64.5grs of Winchester 760 with a 165gr bullet.I'm getting 3125fps with this load.Hornady manual is showing 69.1grs @ 3150fps.That's exactly what I got with 65.0grs of Win 760.Now can you imagine what kind of pressure my rifle would have if I loaded the max from the Hornady manual.My Lee manual shows 65.0grs of Win 760 @ 3069fps @ 63200psi.So I'd say I'm shooting right at max.Those extra four grains would put me way over max.I think some WSM rifles have more freebore than mine and can handle the extra few grains with no problem,but I'm sure there are also others like mine that get loaded way too hot,hot enough to expand those primer pockets like some of the brass I've seen.