CIP vs SAAMI

[hill37]

Has anyone done a comparison of the American and European chambers? Is there enough difference to matter? I know I could compare the drawings but I wouldn't know what I was looking at.

[Drillboss]

They are a virtual overlay of one another. There is a very slight difference due to rounding errors of converting English to metric units.

[hill37]

OK Thanks. Do you know if the chamber pressure is close too? I was wondering if the European version has to be changed to be sold here.

[kmon]

From the discussions of PPU ammo when it was being recalled there is a difference in the datum point and definition of headspace

[hill37]

OK With three Grendel loads in the PPU European catalog, I could not understand why it wasn't sold here.

[JASmith]

The folks at SAAMI and CIP worked very diligently to harmonize the two drawings about three years ago.

[MDWS]

CIP looks at headspace a little differently than SAAMI. Converting measurements form imperial to metric loses some translation sometimes, but at the end of the day they should match 99% for the most part.

[Drillboss]

OK Thanks. Do you know if the chamber pressure is close too? I was wondering if the European version has to be changed to be sold here.

CIP standards say Pmax for the Grendel is 4050 bars which is 58,740 psi. SAAMI's MAP is 52,000 psi. I have no idea why there's such a large difference.

My understanding is that CIP standards are mandatory for European manufacturers. SAAMI specs, on the other hand, are voluntary for US manufacturers. Some companies are members of SAAMI, others aren't.

[Drillboss]

From the discussions of PPU ammo when it was being recalled there is a difference in the datum point and definition of headspace

I spent tens of minutes researching this, so I don't know how definitive my conclusions are.

CIP standards simply state "Headspace on Shoulder" while SAAMI chooses an arbitrary diameter of 0.35" located between the shoulder and neck to establish the headspace dimension. Since CIP and SAAMI are consistent on the length of the cartridge (and chamber) from base to shoulder and the shoulder angle is the same, I'd say that both are using the same headspace specification.

[JASmith]

CIP standards say Pmax for the Grendel is 4050 bars which is 58,740 psi. SAAMI's MAP is 52,000 psi. I have no idea why there's such a large difference.

My understanding is that CIP standards are mandatory for European manufacturers. SAAMI specs, on the other hand, are voluntary for US manufacturers. Some companies are members of SAAMI, others aren't.

Here is a Grendel-centric explanation of SAAMI pressure standards: http://shootersnotes.com/articles/saami-pressure/

My impression is that most US manufacturers load to pressures slightly below the SAAMI MAP to minimize product liability exposure.

The velocities we see in European and Russian Grendel ammunition might suggest they are even more aggressive about staying away from the ceiling.

[hill37]

The 123gn load in PPU's catalog converts to about 2600f/s (810m/s) from a 24inch barrel. Hornady sst is 2580. I can't see any why PPU will not sell hear.

[NugginFutz]

Here is a link to both drawings, posted 2014.

http://www.65grendel.com/forum/showthread.php?8080-Official-SAAMI-and-CIP-6-5-Grendel-Drawings&p=87586&viewfull=1#post87586

You can download the PDFs from that post.

[VASCAR2]

The 123gn load in PPU's catalog converts to about 2600f/s (810m/s) from a 24inch barrel. Hornady sst is 2580. I can't see any why PPU will not sell hear.

PPU did sell their 6.5 Grendel ammunition here but they had batches/lots of ammo which had blown primers here in the US. Prvi Partizan never disclosed their reasoning for recalling their ammo other than to mention there was a difference in some chambers which shot 6.5 Grendel ammunition.

I suspect PPU realized they had issues with some lots of ammo having bad brass or high pressures. To limit liability concern they pulled their 6.5 Grendel ammo and issued a recall. Serbian Military was testing 6.5 Grendel Ak variant M17 and the recalled ammunition could be used in a controlled test with the new weapon system.

PPU is reportedly releasing new 6.5 Grendel ammunition later this year. I hope PPU releases a new higher quality brass case with small rifle primer.