Are magnum primer cups thicker?

dahermit · October 28, 2017, 11:00 AM

Having admittedly already hijacked the thread, "In a Pinch", I wish to apply logic to the issue titled above.

Consider that no primer manufacturer will ever suggest that it is acceptable to exceed the pressure limits as set by ASCII. Furthermore, standard primer cups are considered capable of attaining those pressure limits without the threat of structural failure. In other words, most loads use standard primers to attain maximum pressures without failure.

Also, consider that manufacturers recommend magnum primers only for the purpose of igniting difficult to ignite powders...not to exceed the pressure limits for that cartridge. From what I have garnered over the years is that the manufacturer uses a priming mixture that provides a hotter, longer flame duration (http://www.cci-ammunition.com/produc...ers.aspx?id=29 ).

Therefore, the logic does not support why a manufacturer would need to use a thicker cup for magnum primers.

Nevertheless, my logic could be faulty...actual measurements would be a better assessment. Although I have measured Federal Small Pistol Standard Primers and found that my admittedly primitive dial calibers indicate that both have a cup thickness of .016 of an inch, I will not generalize my result to all primer brands, and types (Small Rifle, Large Rifle, etc.).

hounddawg · October 28, 2017, 11:31 AM

I hope these links are acceptable to the mods

http://www.accurateshooter.com/techn...sure-analysis/

dahermit · October 28, 2017, 01:18 PM

Quote:

I hope these links are acceptable to the mods

It depends on how they feel about multiple drive-by's I would imagine.

hounddawg · October 28, 2017, 01:32 PM

Quote:

It depends on how they feel about multiple drive-by's I would imagine.

well since they all repeated the same basic info we will edit it down to a single article which verified that on small rifle magnum primers the cup thickness is 25% thicker

edit all pistol primers seem to be .017 cup thickness

Marco Califo · October 28, 2017, 01:41 PM

Yes, magnum primers including CCI milspec #41 SR and #34 LR, do have thicker cups, appropriate priming compound to ignite "ball" powders, and I believe the anvil structure can vary. UncleNick (mod) talks to CCI and other primer makers and will post specifics any time now. The thicker cups also resist slamfire in rifles with floating firing pins.
Can non-magnum primers experience structural failure? Define structural failure. I have experienced pierced primers (pressure sign) with hot loads using CCI 400's. But certainly NOT catastrophic failure. No more since I switched to #41 and Tula 556M.
So, yes, there are real differences. If you choose to use ball type powders, and/or load for a gas operated gun, or try to attain highest velicities, then I think magum or milspec primers make a lot of sense. In 223/556, I personally see no advantage to using non-magum primers, even in bolt guns.

flashhole · October 28, 2017, 06:24 PM

I use magnum primers in cartridges with long/tall powder columns for deeper, more uniform ignition. Doesn't have to be a "magnum" cartridge. For example, my 25-06 benefits from using magnum primers.

Stats Shooter · October 28, 2017, 10:26 PM

There's a lot of information folks will give you on primers here. But I'll just answer the question.

In large Rifle primers, no, for the most part. CCi 34's which are mil primers have essentially a longer distance to the anvil but no harder.

In small rifle primers yes. Also, CCI's BR-4 have a harder cup than CCI 400.

I use small rifle magnum primers in auto loaders, BR4, and 450's. I tend to near max on 223

October 28, 2017, 11:00 AM	#1
dahermit Senior Member Join Date: October 28, 2006 Location: South Central Michigan...near Posts: 6,501	Are magnum primer cups thicker? Having admittedly already hijacked the thread, "In a Pinch", I wish to apply logic to the issue titled above. Consider that no primer manufacturer will ever suggest that it is acceptable to exceed the pressure limits as set by ASCII. Furthermore, standard primer cups are considered capable of attaining those pressure limits without the threat of structural failure. In other words, most loads use standard primers to attain maximum pressures without failure. Also, consider that manufacturers recommend magnum primers only for the purpose of igniting difficult to ignite powders...not to exceed the pressure limits for that cartridge. From what I have garnered over the years is that the manufacturer uses a priming mixture that provides a hotter, longer flame duration (http://www.cci-ammunition.com/produc...ers.aspx?id=29 ). Therefore, the logic does not support why a manufacturer would need to use a thicker cup for magnum primers. Nevertheless, my logic could be faulty...actual measurements would be a better assessment. Although I have measured Federal Small Pistol Standard Primers and found that my admittedly primitive dial calibers indicate that both have a cup thickness of .016 of an inch, I will not generalize my result to all primer brands, and types (Small Rifle, Large Rifle, etc.).

October 28, 2017, 11:31 AM	#2
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	I hope these links are acceptable to the mods http://www.accurateshooter.com/techn...sure-analysis/ __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek Last edited by hounddawg; October 28, 2017 at 01:28 PM.

October 28, 2017, 01:41 PM	#5
Marco Califo Senior Member Join Date: April 4, 2011 Location: LA (Greater Los Angeles Area) Posts: 2,617	Yes, magnum primers including CCI milspec #41 SR and #34 LR, do have thicker cups, appropriate priming compound to ignite "ball" powders, and I believe the anvil structure can vary. UncleNick (mod) talks to CCI and other primer makers and will post specifics any time now. The thicker cups also resist slamfire in rifles with floating firing pins. Can non-magnum primers experience structural failure? Define structural failure. I have experienced pierced primers (pressure sign) with hot loads using CCI 400's. But certainly NOT catastrophic failure. No more since I switched to #41 and Tula 556M. So, yes, there are real differences. If you choose to use ball type powders, and/or load for a gas operated gun, or try to attain highest velicities, then I think magum or milspec primers make a lot of sense. In 223/556, I personally see no advantage to using non-magum primers, even in bolt guns. __________________ ............

October 28, 2017, 06:24 PM	#6
flashhole Senior Member Join Date: February 9, 2005 Location: Owego, NY Posts: 2,000	I use magnum primers in cartridges with long/tall powder columns for deeper, more uniform ignition. Doesn't have to be a "magnum" cartridge. For example, my 25-06 benefits from using magnum primers. __________________ ,,, stupidity comes to some people very easily. 8/22/2017 my wife in a discussion about Liberals. Are you ready for civil war?

October 28, 2017, 10:26 PM	#7
Stats Shooter Senior Member Join Date: August 26, 2016 Location: North Dakota Posts: 1,636	There's a lot of information folks will give you on primers here. But I'll just answer the question. In large Rifle primers, no, for the most part. CCi 34's which are mil primers have essentially a longer distance to the anvil but no harder. In small rifle primers yes. Also, CCI's BR-4 have a harder cup than CCI 400. I use small rifle magnum primers in auto loaders, BR4, and 450's. I tend to near max on 223