Range Trip...

[laylandad]

I loaded up some 180gr PT and 165gr AB to try in my new to me Rem. 700 30-06. I loaded them up in new Nosler brass with WLR primers and IMR 4350. Velocity and accuracy were good for the most part with the PT. The AB will need some work! I did have a problem with the third string of PT. With 53.0gr of IMR4350 I had a blown primer! I have never had this happen to me. It scared the #$%^# out of me. I was hesitant about continuing, but with no sticky bolt lift or bulged case, I proceeded with caution. Here are a few pics:

I think I'll stick with the #5 load. That should take care of anything in North America! My average velocity with that load was 2677 fps.

Here is the primer in question. This was a middle of the road load and new brass. It was the only one like it. The load was 53.0gr IMR 4350. Any suggestions?

 

[Oldtrader3]

I tried to assist Bill (Elkman) with a similar situation about two years ago. Bill mysteriously blew a Remington primer in a normal looking R-P case which upon examination with a gauge block appeared to be in dimensional spec. The outcome of a detailled dimensional analysis, a little stress and strain analysis and measurement with calipers and the RCBS gage block with dial indicator, over all relevent surfaces on the the case, did not yield a straightforward reason for that particular primer to have failed in tensile. It appeared to have been a primer material failure. I do not think that Bill has had a repeat of this problem?

At this point without actually seeing the case and primer and doing a detailled dimensional profile and examnination likke that which I did for Bill, I can not offer any greater insight into your issue. If I can help you in any way, let me know?

 

[DrMike]

Your choice on the 180 grain load looks quite solid. As to the primer blow-by, it happens occasionally. I'll suggest there was a weak spot in the metal or the pocket was marginally out of spec. It happens. You have a good load worked up, it would appear to me.

 

[laylandad]

Thanks for your reply. It does appear to be a primer issue. It looks as though the side of the primer cup gave way and vented at an angle. I can tell you that when seating the primers, a few of the primer pockets felt loose. Could this be part of the problem?

 

[laylandad]

You're right Dr. Mike! I am very pleased with this load. I wish that I could have held that last round in the same hole as the others. I think that it was a combo of trying to keep it in and barrel heat.

I also wish that the AB would have grouped a little better than it did. The velocity was right on with Nosler #6. Maybe a different powder or playing with seating depth will help.

 

[DrMike]

A final round walking out of the group is not that uncommon; I had it happen at least twice today with a 7STW I was working up. Still, the data was good and the accuracy was there. AccuBonds can be frustrating. I have a 300WSM that just doesn't shoot them all that well, though it assuredly likes Partitions. Go figure! Still, your groups look pretty good from this vantage point. Five shot groups will never happen in the field, though they do tell you quite a bit about the load.

 

[Oldtrader3]

Loose pockets allow the primer cup more rooom to expand and shear from tensile stress. You are increasing the OD of the primer pocket which allows more stretching of the primer metal. I did some stress alaysis for Bill on the cup and primers require being seated in firm contact with the pocket wall brass or they can blow. They usualy shear and blow in the corner as you described. This tendency to shear is brand specific because of materials and hardness of brass cup.

I have a couple of instances as well, where PT's were more accurate than AB's. I am still trying to figure out why the difference? However, one bullet is flat base and the other is boat tail and hey do fly with very different physical properties.