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Changing primers during load development?

 
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  #8  
Old 10-30-2011, 12:40 PM
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Join Date: May 2011
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Re: Changing primers during load development?

Quote:
Originally Posted by johnnyk View Post
SpotHogg32,
All the reloading instructions say anytime you change components, drop the powder chage and work up. This really applies when you near max load. Here are a couple of links, hope they help in your quest/decision.

Primer cross reference chart

Primer Testing Reference

JohnnyK.
Johnnyk,

Thanks for the links this was great information I am going to give the GM210 primer a try and reduce my load and work up again!
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  #9  
Old 10-30-2011, 12:47 PM
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Re: Changing primers during load development?

Quote:
Originally Posted by Spothogg32 View Post
Man I tell you one thing this Broughton barrel is an incredibly low pressure barrel!
Hope your 7mm barrel's not like a 30 caliber one a friend had some years ago. He had it fitted and chambered for .30-.338 then started working up loads. At several grains over published max, he decided to have the bore/groove dimensions checked. They were .303" and .311" instead of the normal .300" and .308".

He called Douglas Barrels and asked why his 30 caliber barrel had way oversize bore and groove diameters. Douglas said they probably mismarked a rifled blank made for 7.65 Argentine Mauser or .303 British as a 30 caliber one.

If your barrel belonged to me, I'd check its bore and groove diameters.
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  #10  
Old 10-30-2011, 01:03 PM
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Re: Changing primers during load development?

Quote:
Originally Posted by Bart B View Post
Hope your 7mm barrel's not like a 30 caliber one a friend had some years ago. He had it fitted and chambered for .30-.338 then started working up loads. At several grains over published max, he decided to have the bore/groove dimensions checked. They were .303" and .311" instead of the normal .300" and .308".

He called Douglas Barrels and asked why his 30 caliber barrel had way oversize bore and groove diameters. Douglas said they probably mismarked a rifled blank made for 7.65 Argentine Mauser or .303 British as a 30 caliber one.

If your barrel belonged to me, I'd check its bore and groove diameters.
I do not know if you are familiar with the 5C canted lands barrel that Broughton produces but they advertise on their web site that it reduces breech pressure and can increase velocity with very low fouling biuld up for easy cleanability. All of these things I have experienced with this barrel and I have shot groups at 100 at 1/3 to 1/4 moa with the gun. I also have a buddy that has a 300 UM and 338 UM with these barrels with similar results.
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  #11  
Old 10-31-2011, 02:19 PM
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Re: Changing primers during load development?

Changing primers is like changing the octane of the fuel onyour 1970 model Ford. You need to fine-tune the carburator for peak performance. Each kind of primer has it's ideal load combination for peak performance.
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  #12  
Old 10-31-2011, 10:46 PM
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Re: Changing primers during load development?

Well guys, I made it to the range today with some new loads that I worked up in .5gr increments using the fed gm210m primer and was very pleased with the results. I shot 5 different 5 shot strings with the 5 different loads and my ES improved a bunch I finally made it into the 12 to 15 fps range for 5 shots! I finished the day with my final load with a 180gr Berger VLD with 72gr of H1000 with a COAL of 3.540" and an avg. 5 shot velocity of 2972fps. My velocity with the CCI 250 magnum primer was only 36fps faster with the same charge. My groups were also holding right at 1/2 MOA or less for 5 shots. An other interesting thing I noticed is the primers on all 25 cartridges had not really started to flatten they just had the primer dent in them and that was basically it with no other signs of pressure! the CCI 250 primers were slightly flattened at the starting load of 70gr and stayed basically the same with the finishing load of 72gr. My next trip out I plan on loading up to 73gr to see if I can get back to the 3000+ fps that I was at before and see if I can maintain the 1/2 MOA accuracy. After that I plan on playing with my seating depth with the Bergers to see if I can get it closer to 1/4 MOA like I did with the 168gr Berger. For some reason the 168gr liked a bunch of jump start .o63" off the lands. Thanks for all of your input and good luck on all of your ventures!
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  #13  
Old 11-01-2011, 09:35 AM
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Re: Changing primers during load development?

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  #14  
Old 11-01-2011, 09:37 AM
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Re: Changing primers during load development?

Quote:
Originally Posted by Spothogg32 View Post
I do not know if you are familiar with the 5C canted lands barrel that Broughton produces but they advertise on their web site that it reduces breech pressure and can increase velocity with very low fouling biuld up for easy cleanability.
That's a good thing. But Broughton should make accurate pressure measurements with strain gages then list load data; all in accordance with SAAMI standards.

SAAMI test barrel's chamber and bore specs are different that Broughton's but if they provide these specs along with load data from standard pressure barrels, then folks will know for sure what loading data is accurate. Otherwise, 'cause the rest of us mortals are poor judges of pressure when it comes to reading case and primer deformations. And SAAMI pressure test barrel specs are based on conventional rifling with land and groove dimensions tightly specified dimensionally so Broughton's pressure test barrels should be also.
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