Primer leakage ?

[Broz]

I reloaded some NEW RWS brass the other night for a friend. This is for the 7mm / 300 win. I sold him. We were switching over to RWS brass from Rem and WW in a attempt to get the load into longer lasting brass. Although we have not seen any problems with prior brass and the load. I just like to use Lapua or RWS were I can.

The load is 77 gr of H-1000 with a 180 Berger .115" off the lands. CCI 250 primer. This rifle has proven to be very accurate with this load.

I advised him to check his 250 yard zero as the brass change could affect velocity. He just called me and said he fired a group at 250 and the elevation was good but he had some horizontal. He also stated that the primers were leaking around the edge. He said all looks good but they all leaked. I asked about bolt lift and signs of pressure and he said they all were good.

I should add this is new brass and we had some runout due to the necking down process. I did square the primer pockets like I do on all brass, and of course I deburred the flash hole. I seated the primers with a RCBS hand primer tool and they all went in nice and tight.

I havent seen the fired brass yet but right now I am at a loss. Anyone seen this before?

Thanks!

Jeff

 

[gunrac]

If you are talking blowback between the primer an brass, especially new brass, I might consider that a pressure sign.

 

[Chas1]

I'd stop shooting and go to this link, read pargraph 10.

Primer Myths

 

[Broz]

Thanks guys. I haven't seen the fired cases yet. He stopped firing and called me as he thought something may be wrong. But he told me there was no cratering going on and the the primers are still seated and didn't appear to be loose. We have fired many rounds through the rifle with this charge and this powder lot. The only change was the brass mfg. From my experience with the 300 win and 210 bullets this is not a over max load by any means. Plus, this is with a 7mm 180 gr bullet, and he didn't experience any gained elevation at his 250 zero. However I will look at the brass later today and I will hand punch out the spent primers to see if they are loose, look it over for any sign of pressure.

I appreciate the replies. I just wanted to see if here was any other know cause other than over pressure.

Thanks!

Jeff

 

[RockZ]

I had some leakage in my 204 Ruger. I was using FED 205M with no problems and then tried CCI primers.
I was getting alot of leakage around the primer with the CCI's with the same load velocity, and accuracy as the FED 205M so I don't think it was a pressure problem.
Went back to the FED 205M and no problems again.
I just don't think they fit the primer pocket of my brass as well or didn't seal as well.
Just a thought.

 

[gunrac]

Rule of thumb; I'm sure most have read an even experienced it. Change 1 component, back off your load and work up again.

Good read their, Chas1. Thanks

 

[Chas1]

Broz, let us know what you find.

 

[Broz]

Rule of thumb; I'm sure most have read an even experienced it. Change 1 component, back off your load and work up again.

Good read their, Chas1. Thanks

I hear you and agree 100%. But we had been quite a bit higher with this load during development. We reduced it for accuracy as the sweet spot was not at max. I will take accuracy over velocity any day. So I felt we were in a safe spot but cautioned him to fire one, to check zero and watch for bolt lift or shiney spot on the case heads. He says that is all good. I will make sure before any more are fired.

This could very well be pressure and if so , bullets will be pulled and charge reduced.

Thanks
Jeff

 

[RockZ]

Just a note.
I did work up the load with the cci's and was getting leakage even at the lower load pressure /velocity levels.
Didn't notice till I shot a few though since the velocity was low and no difficult bolt lift and no marks on the case head. Now I get out in the sun and take a really good look at the primers when working up loads.

 

[Broz]

Hey Guys, Just wanted to follow up and report my findings. I just last evening got to look at the fired cases. They were definatly a bit over pressure. Here is what I found. Slight ejector pin circle was visable on the headstamp. Just enough that a very close look and you could make it out but not enough for hard bolt lift. This is the same exact spot where every pocket leaked, and the only spot. So it is my conclusion is that under this high pressure spike the pocket deformed slightly and let a bit of gas leak out next to the ejector pin. Also, the primers were definatly cratered a bit, not alot but I could catch y thumb nail on it.

I punched out the primers and put them on my primer pocket squaring cutter. The pocket are still true and round. I then seated new primers to see if the pocket was enlarged. The new primers fit nice and firm. I also did an inside mic of wall thickess right above the belt to look for a weakened area. None was evident. So I feel they are good to go again.

I believe the problem was due to the reduced inner case area of the RWS. This made the % of case fill higher and increased pressure. Also, this was the warmest ambient temps we have ever fired the rifle in. I also believe we were closer to max than I origionally thought. So all bullets will be pulled and new powder charge will be developed.

Just wanted to add my findings to the thread in case anyone else ever has a similar issue.

Thanks for all the replies.

Jeff

 

[trueblue]

I would say you are spot on in regards to the thicker brass giving less case capacity, and raising your pressure slightly.

 

[Chas1]

Broz, thanks for sharing. Looks like a couple of things were going on there. Good to hear they're still reloadable.

 

[RockZ]

Broz,
Thanks for the update.
I too noticed the rws brass has a much smaller internal capacity than the Norma brass.
2-3 grains less of h1000
I'll have to measure the water capacity when I get back in town

 

[Broz]

Broz,
Thanks for the update.
I too noticed the rws brass has a much smaller internal capacity than the Norma brass.

Tonight we worked the load back up. 2 gr less than the old load and it was happy but we found it was a bit more accurate with 3 gr less so we went with that. The interesting thing was after reducing the load it was spot on at its 250 yard zero. I don't think we lost much velocity. Time will tell on that when we shoot at distance. Whle loading I weighed one of the old Rem cases and one of the new RWS. The Rem weighed in at 243 gr and the RWS weighed in at 278 gr. So there is quite a difference.

Jeff