Blowing out primer at below recommended start load 300WM

I started getting this problem when I switch from Berger 210 BTLR to 210 VLDs.

Click to expand...

The VLD may have a longer bearing surface, thicker jacket then the other bullet. Seating the VLD base deeper into the case may raise pressure. Brass that is heavier then the brand used in the load data may raise pressure. The ogive into the rifling may raise pressure. http://www.bergerbullets.com/wp-content/uploads/2013/03/COAL.pdf How are the primers "blown out" Pierced/blanKed, faling out of the brass, gas leakage between primer and brass, hole in rounded corner of the primer cup??

You may want to confirm the load data from another source.
The next stop should be the powder manufacturers recommendations if possible. Normally they are available on line.
Luck
T

Berger tests regular vs. thick jackets with Bartlein - Unexpected Results

http://benchrest.com/showthread.php?59141-Berger-tests-regular-vs-thick-jackets-with-Bartlein-Unexpected-Results

We started shooting the thick jacket bullets but 11 of the first 15 rounds had blown primers.

Click to expand...

02-06-2009,

My first guess would be the brass is a lot heavier than what the load data is using. But if you read post #4 above, it may be the bullet construction?? A bullet jammed into the rifling will raise pressure.

I'm BELOW the recommended start load

Click to expand...

This may cause problems also. If your loading using the exact same componants used in Berger's manual for 210 gr VLD target, then the below recommended powder charge may be a problem??

Like said above, that bullet is very long and it's possible you are into the rifling.

You gave us a lot of information you got from the Berger load manual but you did not tell us what COAL they tested the data at. Did you keep using the same OAL as you were loading with the Berger 210gr BTLR when you switched to the 210gr VLD bullet? If you did you are probably into the rifling like the above posts suggested and that will raise the pressures, sometimes by a lot.

Bullets look about the same. Construction & Bearing surface may be different? Had to tell.

Norma brass is the heaviest, thickest brass available. It will reduce case capacity by a few grains.

Did you use Norma brass before with the other bullet?

If you want to, fill a Norma case with water then pour it into a different manufacturers case and see how much difference there is.

Does Berger call for Norma brass in their load data?

Are you shooting over a chrony?

Have you checked with ALLIANT for a recall on that batch of RE-22?

Have you checked with Norma for a recall on that batch of brass? Perhaps it was "super-sized" from the factory.

Have you measured the diameter of bullets from Berger to confirm they are proper diameter?

Have you slugged your barrel to check diameter?

Does the barrel heat up very quickly compared to the previous loads, indicating a bullet to bore problem?

Have you checked head space?

In revolver rounds, which I have lots of experience with, if you go too low, the primer can back out.

With proper loads, the case is pushed so hard against the recoil shield that either:

A. the primer isn't allowed to start to come out

or

B. the primer starts to come out, but is reseated when the case is pushed back against the recoil shield.

I'm not well versed on rifle reloading (all I have is an AR-15).
Is it possible your below standard load is too soft???

At least this gives you another avenue to consider.

Generally there is little mystery to reloading mishaps, at least in my experience. As for this problem, I can only use past experience to try and diagnose the cause.

Not too long ago my Son picked up a bunch of 7mm RM from a yard sale. The loads were all below, in fact significantly below published minimum using a slow burning powder IMR-4350. Rather than let me pull the bullets and re-do the loads, my Son insisted on just shooting them up so we could get to loading the brass. What happened, is most of the primer's were backed way out, black sooty brass, and obvious signs of blow back over the case shoulders also. Some primers actually pierced, most all leaked, and extraction was stiff, very similar to that of an over charge high pressure load.

Slow burning powders such as RL22 do not perform well when taken down below published minimum. I load regularly with this powder and have seen how it behaves.

Providing there are no unmentioned issues such as brass that is exceeding maximum length, what is the resized length of the brass? 300 WM does have a short neck to start with, and is some what prone to pinching in the throat when not maintained within spec..

Other wise I strongly lean toward light powder charges simulating high pressure effects as the likely culprit here.

Another possible is seating depth, although I doubt at that powder charge that seating into the lands would raise pressures enough to result in blown primers. It's never happened to me, and I commonly seat right up to the lands, and even slightly into them with powder charges at or above mid table.

GS

As far as highpowered rifles are concerned; I have read and heard that less powder can build up pressure quicker than more powder. I am not an expert, I have only been reloading for about 2 years. However, I am still not clear why you went outside of the data? I am honestly asking.

It might be from the flash, but is that a mark on the right bullet Also looks like a ring from the seating stem right above it. If the VLD round was chambered in the rifle, you may have a short, tight throat/leade in your custom barrel.

Just a thought, but check your case length.


405

You are loading your VLDs into the lands, correct.

Loading into the lands will cause a higher pressure situation than what your manual intended.

Back the charge down or seat the bullet deeper!

Loading into the lands will cause a higher pressure situation than what your manual intended.

Click to expand...

Maybe, but maybe not. Berger suggests seating the vld to the lands; their manual may be based on that.

FWIW, I had a fast lot of Rx25 a while ago.

As mentioned above, check your brass length. I would also clean the barrel.

Do you have check weights? Your scale could be lying to you.

BTW, I'm reading everybody's responses. The thing is, I didn't have a problem with pressure with the BTLRs before. However, I have since changed R-22 lot numbers. So, I'm now thinking that the powder lot may be hot as someone suggested. I'll see if I can call them tomorrow.

Click to expand...

Powder is blended, Accuracy Arms told me the industry standard is + - 10%. If you changed powder lot, primers, case, bullets, anything, don't assume pressures will stay the same.

If you are blowing primers, cut your loads. I would cut by a grain, then continue to cut by a half grain till the primers stop blowing.

Books are guides, each gun is different.

At this point, I'm betting that the technician reviewing your chambers blue print is going to yield some possible answers. I'm kind of leaning toward a shorter or tighter than industry standard (SAAMI) throat that may be causing the mouths to get pinched or restricted, even though the brass is trimmed to minimum and even with projectile not into the lands? Your chamber may need some additional work, might be too tight one way or another by just a smidge.

GS

It was suggested the bullets could be load specific.

F. Guffey

Question, do you turn your case necks at all?