Pressure Issue?

[shotguntom]

I used some Sellier & Bellot eXergy Blue 150gr in my 7x57 the other weekend and noticed that on pretty much all the fired rounds (approx 20) the primers were raised about 1mm and on 2 rounds the firing pin penetrated through the primer.

No other signs of pressure, such as a stiff bolt or marks on the bolt face.

Any suggestions?

I emailed S&B and they could not give me a definitive answer. They looked into the lot number and it is within their acceptance protocols - The pressure was 300MPa with the C.I.P max is 390 MPa. They suggest it could be a mix of slightly higher pressure, primer lot with bottom thickness at the lower limit, rifle chamber clearance or firing mechanism.

I’ve shot all sorts of ammo through the rifle (Heym SR20) and never had the issue before.

 

[KimE]

I can not see pressure issues on the primers or cases, it might be headspace is too short so the primers jump back before the case has expanded, or thin primers so they just are pierced.

 

[HonestJohn]

its not over pressure, its under pressure. dates back to legal risks of the 7x57 being used with small ring mausers

 

[Smellydog]

No issue at all.
Typically during firing the case grips the chamber without moving rearward except for the cartridge head but first the primer naturally backs out. Then the cartridge head backs out over the primer again.
In your case there wasn't sufficient pressure to force the cartridge head back over the primer.
A non issue.

 

[HonestJohn]

its not over pressure, its under pressure. dates back to legal risks of the 7x57 being used with small ring mausers

solution - reload or buy RWS/Norma, both run relatively hot in 7mm mauser. federal are the worst for aenemic ammo in 6.5 swede and 7x57 as they worry about getting sued for blowing up a rifle/injury via old military rifles not proofed or tested to large ring mauser standards

 

[WildBoarHunter]

I l've had the same issue using 6.5×57 Sellier Bellot 131 gr SP. Most of their loads are underloaded. The above mentioned is downloaded about 10% and is the same as the rimmed load 6.5×57R.

 

[shotguntom]

Thanks for all the responses - very insightful! The rounds group well in my rifle and performance on deer was very good too - 3 fallow bucks shot at 200 yards on or just behind the shoulder and none went more than 10m. So, im hesitant to move away from them.

 

[25 Sharps]

Thanks for all the responses - very insightful! The rounds group well in my rifle and performance on deer was very good too - 3 fallow bucks shot at 200 yards on or just behind the shoulder and none went more than 10m. So, im hesitant to move away from them.

They are good bullets but, you don’t want escaping gases damaging your firing pin or bolt face!

 

[Bowland blades]

I used some Sellier & Bellot eXergy Blue 150gr in my 7x57 the other weekend and noticed that on pretty much all the fired rounds (approx 20) the primers were raised about 1mm and on 2 rounds the firing pin penetrated through the primer.

No other signs of pressure, such as a stiff bolt or marks on the bolt face.

Any suggestions?

I emailed S&B and they could not give me a definitive answer. They looked into the lot number and it is within their acceptance protocols - The pressure was 300MPa with the C.I.P max is 390 MPa. They suggest it could be a mix of slightly higher pressure, primer lot with bottom thickness at the lower limit, rifle chamber clearance or firing mechanism.

I’ve shot all sorts of ammo through the rifle (Heym SR20) and never had the issue before.

Well any of the dealers i have used and continue to use have all taken back such ammo and sent them back . You have no contract with anyone but the dealer that sold them , its for them to return and i have never known an issue or even a grumble ( this sort of thing keeps us all safe at the end of the day )