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Help with 300rum

 
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  #1  
Old 01-11-2008, 09:39 PM
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Join Date: Jul 2007
Location: HB New Zealand
Posts: 17
Help with 300rum

Hi everyone, I'm currently developing a load for my Sendaro sf11 300rum, using Nosler Brass ADI AR2225 powder Fed 215m primers and 210vld projectiles. The problem is that the primers are cratering once I get above 90gns, 92gns gives me an ave velocity of 2930 fps using a Pact XP Chrono which I would not have thought enough to bring on excessive pressure, no other pressure signs are seen ie sticky extraction, flattened primers etc although case head expansion seems to be getting near max,
These are my views on what could be causing the cratering

- Too much Powder
- Primer pockets to deep causing metal to flow back before the primer moves back to the bolt face.
- Oversized firing pin, measures .0735 in diameter
- operator error

Anyway I'm just wondering what the knowledgable people here think, also if it were a firing pin issue wouldnt cratering be noticed at lower pressures as well?
Sorry I cant post a pic

Many thanks Callum
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  #2  
Old 01-12-2008, 04:46 PM
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Join Date: Jan 2008
Posts: 3
i use the retumbo, 90g with berger 210g bullets o.a.l of 3.8 inches. with a 26 inch barrel will get you 3050f.p.s 3 shot groups i got with my 300rum were about .5 inch no pressure signs
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  #3  
Old 01-12-2008, 09:17 PM
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Join Date: Dec 2005
Location: N. TX
Posts: 92
Quote:
Originally Posted by FlinchedAgain View Post
Hi everyone, I'm currently developing a load for my Sendaro sf11 300rum, using Nosler Brass ADI AR2225 powder Fed 215m primers and 210vld projectiles. The problem is that the primers are cratering once I get above 90gns, 92gns gives me an ave velocity of 2930 fps using a Pact XP Chrono which I would not have thought enough to bring on excessive pressure, no other pressure signs are seen ie sticky extraction, flattened primers etc although case head expansion seems to be getting near max,
These are my views on what could be causing the cratering

- Too much Powder
- Primer pockets to deep causing metal to flow back before the primer moves back to the bolt face.
- Oversized firing pin, measures .0735 in diameter
- operator error

Anyway I'm just wondering what the knowledgable people here think, also if it were a firing pin issue wouldnt cratering be noticed at lower pressures as well?
Sorry I cant post a pic

Many thanks Callum
FA - I have recently read on long range hunting an excellent post on pressure signs and how they can be deceiving, dont recall where the post is (most likely here in handloading), but I am sure with the right search terms you will find it, the smith recut his bolt face, and then modified the firing pin to get rid of the cratering, this is a boiled down version of what they did - so I would vote for the firing pin. I have experienced this on a H&R single shot I bought back in the day, same problem - firing pin slop and issues with it, NOT pressure. I would bet that if you keep using this rifle you will get a pierced primer with higher pressure... I am assuming that this rifle is new, or that you have checked it against other loads to verify that it happens across the board.... if it doesnt, then maybe the brass - FYI I am using the Nosler brass, 210 Berger VLDs and Retumbo - no problems here. Have you shot any factory ammo out of her yet?

EZ
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  #4  
Old 01-12-2008, 11:43 PM
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Join Date: Sep 2004
Location: on the rifle range in Utah
Posts: 2,723
The Nosler brass is very good brass but it is soft and will not hold as much powder as REm brass.

With either brand, try H1000 and around 91 grains or so. Should give 3100-3200 fps and gives 100% load density without compressing powder. Oh yeah, it is usually very accurate too.
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