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Primer choices. Rifle,pistol,magnum...?

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Looks like the SRP (400) won.  Thanks for the testing, about the only other test would be a Ransom Rest accuracy check.

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I don't have a ransom rest, but am pretty good at 50 yards from bench. I'm evaluating the accuracy of Montana Gold 115 & 124 CMJ's next and will incorporate these 3 different primers into that. The MG JHP's are the 'gold' standard of accuracy - hoping the CMJ's can live up to that. If so, no more picking corn cob out of my JHP's!

 

Also, there wasn't much difference that I can see in the primers regarding flattening. All look good - see pic below.

I removed the primers from these case and measured their diameters - interesting, and not exactly what I was expecting.

A side note, these CCI500 primers were purchased in 2008. The 550 and 400 primers purchased this week.

unfired (all)  -  .175"

CCI 500  -  .176"

CCI 550  -  .179"

CCI 400  -  .179"

 

1462955168_primercomparison.thumb.jpg.44838a538087d730c396dd4755561ae4.jpg

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5 hours ago, racer-x said:

I don't have a ransom rest, but am pretty good at 50 yards from bench. I'm evaluating the accuracy of Montana Gold 115 & 124 CMJ's next and will incorporate these 3 different primers into that. The MG JHP's are the 'gold' standard of accuracy - hoping the CMJ's can live up to that. If so, no more picking corn cob out of my JHP's!

 

Also, there wasn't much difference that I can see in the primers regarding flattening. All look good - see pic below.

I removed the primers from these case and measured their diameters - interesting, and not exactly what I was expecting.

A side note, these CCI500 primers were purchased in 2008. The 550 and 400 primers purchased this week.

unfired (all)  -  .175"

CCI 500  -  .176"

CCI 550  -  .179"

CCI 400  -  .179"

 

1462955168_primercomparison.thumb.jpg.44838a538087d730c396dd4755561ae4.jpg

Thank you for sharing these results. So were these average diamater numbers and what was the variation? Did you notice a difference in velocity between the primers? 

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8 hours ago, racer-x said:

Also, there wasn't much difference that I can see in the primers regarding flattening. All look good - see pic below.

I removed the primers from these case and measured their diameters - interesting, and not exactly what I was expecting.

A side note, these CCI500 primers were purchased in 2008. The 550 and 400 primers purchased this week.

unfired (all)  -  .175"

CCI 500  -  .176"

CCI 550  -  .179"

CCI 400  -  .179" 

 

 

The zero was off a hair on my caliper. Here are the updated results:

CCI 500  -  .175" (+/-.0005)

CCI 550  -  .178" (+/-.001)

CCI 400  -  .178" (+/-.001)

 

New (unfired) primers (CCI500, 550 and 400) all measured precisely  .1745" - no variations found

All primer pockets measured .172" - no variations found over mixed head stamp brass.

 

All of these primers started out as the same .1745" diameter pressed into a .1720" primer pocket.

These results indicate the 550 (SPM) and 400 (SR) primers expanded more than the CCI 500 SPP's.

I expected the opposite result since SPP's are generally expected to be softer than SPM or SR.

 

Only explanation I can think of is that these 500's I have (purchased in 2008) are from a batch when CCI built the reputation of having the hardest & most difficult to ignite SPP.

 

Will be interesting to test again with a current batch of CCI 500's...

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