Federal small pistol primers No 100 vs GM 100

[StrawDog]

Hello to all,
I’m looking to substitute GM 100 primers for the more familiar No 100. I need something that is easily dented by a revolver with a weak spring. I’m looking for suggestions such as the Federal GM 100 or anything else.
Thanks

 

[Unclenick]

The GM 100 is identical to the 100. You are just paying extra to have it assembled by the most experienced employees with the idea that it will then be more consistent for match shooting.

 

[StrawDog]

Thank you Nick

 

[akinswi]

The GM 100 is identical to the 100. You are just paying extra to have it assembled by the most experienced employees with the idea that it will then be more consistent for match shooting.

Seriously Unclenick is that the only difference?

 

[Unclenick]

For that pair of primers, yes. The load data for them is no different. The CCI BR primers are another example. You can email Federal and ask, and they will respond and tell you the same thing. The only Gold Medal primer I am aware of that is different from a standard primer is the GM205MAR, which is a GM205M small rifle match primer made with a thicker cup to reduce sensitivity to military specifications for the AR (I have an email from Federal stating that somewhere). The only match primer brand I can think of for which anything more than better precision in manufacturing is claimed is Winchester, which claims greater sensitivity. Sort of the opposite of what you want in a military floating firing pin gun, as the risk of slamfire increases with sensitivity.

 

[Jim Watson]

In these straitened times, I have made some substitutions in reloading; mostly 9mm for IDPA and USPSA. I found little to no difference in velocity by changing primers, SP, SPMag, SR of whatever brand I had.

BUT CCI BR4 small rifle match was notably hard to seat; I resorted to hand seating, much as I dislike going de-progressive. I figure they are not only alleged better QC, they are likely stiff AR cups because a major application would be High Power.
They have all thus far went off in hammer fired 9mms, though.

 

[Unclenick]

Were they hard to seat compared with CCI 400? I'm wondering if maybe they are based on the CCI 450 instead of the 400. It should be possible to call and find out.

 

[Jim Watson]

I suspect they are, plain CCI SR seat readily in 9mm.

 

[Nick_C_S]

Were they hard to seat compared with CCI 400? I'm wondering if maybe they are based on the CCI 450 instead of the 400.

Unclenick, is this to say that there's something different between the 400 and 450? Other than the mixture, giving the 450 a stronger charge?

If the 450 is made with a harder cup, what would make the 450 different from the #41?

 

[Shadow9mm]

Unclenick, is this to say that there's something different between the 400 and 450? Other than the mixture, giving the 450 a stronger charge?

If the 450 is made with a harder cup, what would make the 450 different from the #41?

According to CCI, when I called them a few years back, the 450 and #41 are identical except for the anvil. They changed the angle of the anvil to make the #41 less sensitive.

They also recommend either the #41 or the 450 for use in AR's, or guns with free floating firing pins.

 

[Unclenick]

You can still find James Calhoun's 1995 article on primers and pressure posted online. In it he measured CCI 400 cups at 0.020" thick at the bottom and CCI 450 cups at 0.025". The purpose would not have been to reduce sensitivity when they were designed (the military sensitivity spec commercial primers were introduced later to address based on slamfire reports), but to handle higher cartridge pressures without excessive flattening or mushrooming. They also reduce sensitivity some, but they are not as insensitive as the military sensitivity spec primers.

 

[Nick_C_S]

They changed the angle of the anvil to make the #41 less sensitive.

I remembered the anvil angle thing about an hour after I posted. One of those things I knew, but forgot. Not getting any younger .

Thank you Shadow9mm and Unclenick.

Valuable info. There's a LGS here that has 450's. I think I'll grab a brick, rather than wait for #41's. I haven't seen #41's in a store since before the shortage of '13.

And then there's the fact that I have yet to have a slam-fire using 400's. That said, I won't chamber a round unless I'm at the range, with the muzzle downrange - just in case .