SAAMI's Latest Rifle Cartridge Velocity & Pressure Data

Bart B. · July 2, 2013, 06:06 AM

Interesting new format for SAAMI spec's on cartridges:

http://www.saami.org/specifications_...essure_CfR.pdf

higgite · July 2, 2013, 08:31 AM

Interesting info, thanks.

Some entries have 2 velocity values for the same weight bullet, same caliber, same pressures, etc. Why 2 values? I can't find it notated in the document. Is there a supplemental document?

Bart B. · July 2, 2013, 09:46 AM

Which ones have two speeds for a given weight?

higgite · July 2, 2013, 11:56 AM

There are numerous ones. The one that first caught my attention was when I looked up .223 Rem, 55 grain, on page 4, that shows 3050 and 3215 fps. They are scattered throughout, starting with 6mm Rem, 100 grain on page 1. I wonder if they were tested with different barrel lengths or what? I don't find any footnotes or anything to explain it.

Clark · July 2, 2013, 12:48 PM

Thanks Bart.

I wish they had a free update since 1962 on chamber and cartridge dimensions.

Slamfire · July 2, 2013, 03:50 PM

Very interesting and thanks for posting.

I don't know why some cartridges have two velocities for the same bullet weight, but I would not take it too seriously. These are published as nominal values.

What is important is the pressure criteria. The max average, maximum probable, max probable mean.

The way I understand it, they are attempting to show that pressures vary quite a bit, given the same bullet, with the same lot of powder. Some powders or lots of powder would exceed the pressure limits, holding the charge constant. This would force ammunition makers to test ammunition with a particular lot of powder and stay within the pressure limits.

Bart B. · July 2, 2013, 06:05 PM

Clark, check out:

http://www.saami.org/specifications_...tion/index.cfm

This page has the latest cartridge info. Click on "Cartridge and Chamber Drawings" for the latest ones. I think these are what you're looking for.

Higgite, someone should call SAAMI then ask them about those two velocities for the same bullet weights. The difference appears to be with different barrel lengths, but it may well be something else. I've called them before about issues and they've been more than decent answering my queries.

July 2, 2013, 06:06 AM	#1
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	SAAMI's Latest Rifle Cartridge Velocity & Pressure Data Interesting new format for SAAMI spec's on cartridges: http://www.saami.org/specifications_...essure_CfR.pdf

July 2, 2013, 12:48 PM	#5
Clark Senior Member Join Date: December 4, 1999 Location: WA, the ever blue state Posts: 4,678	Thanks Bart. I wish they had a free update since 1962 on chamber and cartridge dimensions. __________________ The word 'forum" does not mean "not criticizing books." "Ad hominem fallacy" is not the same as point by point criticism of books. If you bought the book, and believe it all, it may FEEL like an ad hominem attack, but you might strive to accept other points of view may exist. Are we a nation of competing ideas, or a nation of forced conformity of thought?

July 2, 2013, 03:50 PM	#6
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	Very interesting and thanks for posting. I don't know why some cartridges have two velocities for the same bullet weight, but I would not take it too seriously. These are published as nominal values. What is important is the pressure criteria. The max average, maximum probable, max probable mean. The way I understand it, they are attempting to show that pressures vary quite a bit, given the same bullet, with the same lot of powder. Some powders or lots of powder would exceed the pressure limits, holding the charge constant. This would force ammunition makers to test ammunition with a particular lot of powder and stay within the pressure limits. __________________ If I'm not shooting, I'm reloading.

July 2, 2013, 06:05 PM	#7
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Clark, check out: http://www.saami.org/specifications_...tion/index.cfm This page has the latest cartridge info. Click on "Cartridge and Chamber Drawings" for the latest ones. I think these are what you're looking for. Higgite, someone should call SAAMI then ask them about those two velocities for the same bullet weights. The difference appears to be with different barrel lengths, but it may well be something else. I've called them before about issues and they've been more than decent answering my queries. Last edited by Bart B.; July 2, 2013 at 06:17 PM.

July 2, 2013, 08:31 AM	#2
higgite Senior Member Join Date: October 21, 2010 Posts: 1,025	Interesting info, thanks. Some entries have 2 velocity values for the same weight bullet, same caliber, same pressures, etc. Why 2 values? I can't find it notated in the document. Is there a supplemental document?

July 2, 2013, 09:46 AM	#3
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Which ones have two speeds for a given weight?

July 2, 2013, 11:56 AM	#4
higgite Senior Member Join Date: October 21, 2010 Posts: 1,025	There are numerous ones. The one that first caught my attention was when I looked up .223 Rem, 55 grain, on page 4, that shows 3050 and 3215 fps. They are scattered throughout, starting with 6mm Rem, 100 grain on page 1. I wonder if they were tested with different barrel lengths or what? I don't find any footnotes or anything to explain it.