Do Federal large rifle primers really have a larger diameter?

[jlow]

I read with interest from James Calhoon’s article in Varmint Hunter Magazine and the Technical Article in our own Accurate Shooter.com that Federal primers (at least the 210s) have a slightly larger diameter i.e. 0.2120” say compared to Remington 0.2100”. Two thousands is quite a bit bigger! Is this the experience of others on this board? Has anyone actually measure it or the 215s?

 

[markm87]

I've not measured it... but I pulled down a bunch of Black Hills "match" ammo to try to make some good ammo out of the stuff...

Anyway... I removed the crimp and could not get Federal Large rifle Match primers to seat fully in several of the pieces of brass. I had to switch to WIN Large rifle primers.

 

[jlow]

Thanks! That is at least consistent with a larger primer. Can someone who has the 210s and 215s take them out and put a micrometer to them?

 

[Elwood]

Blatantly stolen from the post above (now below) this one.

http://www.jamescalhoon.com/primers_and_pressure.php

 

[Steve Blair]

My recent lot of 210M primers average .2109. Some leftover 210Ms from the eighties average .2174.

 

[jlow]

Elwood – yes, that is the data that gave me the impetus for my question. However, you can see that it is dated to 1995 and so my question is does the data still hold true?

Sleepygator – Seems like they are getting smaller? 0.2174” would be huge, that is almost 7 thousands bigger, how does those ever fit in the primer hole?

 

[Steve Blair]

Sorry, .21074. Not enough coffee.

 

[jlow]

Not a problem, just checking… I just measured 12 Remington 91/2 with a Mitutoyo Digimatic Outside Micrometer and this is what I got. You can see both the raw data and the average which ends up being 0.21039” which is slightly bigger than the 0.2100” quoted in the Calhoon article.

What I am trying to find out is if there is a primer which is bigger so that one could use one’s brass longer as the primer pocket gets bigger? Fully realizing that there are other factors such as accuracy/precision that also comes into play big time. The Calhoon article would suggest the Federal primers being the biggest, just wondering if that is still true?

 

[GermanS1]

In my experience, the Russian primers are the largest currently made. I'll try to measure a few brands tonight or tomorrow and post some results. I have primers going back over 70 years (I wasn't the original buyer of many!) and it should be interesting.

 

[jlow]

Thanks German! Looking forward to the results!

 

[Steve Blair]

Pending German's results, here are my samples. All are averages of 10 primers, as before. These are all recent lots. [br]
Wolf KVB-7 LR .21090
Wolf KVB-7M LRM .21080
Win 8½-120 LR .21010
Rem 9½ LR .21070
CCI 200 LR .21100
CCI BR2 .21100 [br]
It is important to mention that diameter is not the only factor. Cup thickness and hardness are both relevant to sealing pockets. All three parameters will vary within manufacturing tolerances as well as from lot to lot. If your loads are opening the primer pockets, the case head metal was pushed into plastic deformation and is likely over recommended pressure. Case head hardness varies by manufacturer and from lot to lot and can show significantly different results with the same load. Always rework a load when changing any component, even a different lot from the same manufacturer.

 

[Elwood]

Elwood – yes, that is the data that gave me the impetus for my question. However, you can see that it is dated to 1995 and so my question is does the data still hold true?

Sleepygator – Seems like they are getting smaller? 0.2174” would be huge, that is almost 7 thousands bigger, how does those ever fit in the primer hole?

I did think "what a coincidence"

 

[jlow]

Thanks guys! It’s interesting that sleepygator’s Rem 91/2 LR seems bigger than mine. I am going to go measure another 12 from another box to see what I come up with.

 

[jlow]

OK, I have measured another 12 primers from a different box and also the first 12 primers again and added the ES and SDEV stats for the three sets. The primers from a different box appears to be slightly smaller in diameter (o.21015” vs 0.21039”) but more consistent (ES=0.00018” vs. 0.00073”). Since the data from this second set appears to be tighter, I thought perhaps this was due to more practice on my part and so I re-measured the first 12 i.e. Looks like those were indeed larger as I got 0.21034” vs. 0.21039” with about the same ES 0.00102” vs 0.00073”.

A quick note as to how I do this – Basically I grab the primer with a gloved hand and place it under the gauge to be captured and measured. I then release the primer and rotate it and then up for a second measurement; repeating a third time for the third data point. The micrometer was zeroed at the start of the session and checked at the end.

So it looks like there is some variability between primers in different boxes but not a huge difference ~0.0002” but this could account for differences between my data and sleepygator’s since he is of course again using a different box, measuring instrument, and perhaps technique.

 

[jlow]

Looks like none of the primers measured thus far (thanks sleepygator!) are significantly biggerat least to the degree originally reported in the Calhoon article.?

 

[dennisinaz]

I measured every brand of primer I had at one time; Rem 9 1/2, WLR, WLRM, BR2, CCI-200, CCI-250, 210. 210M, 215M, Wolf and some old stuff that I can't recall. Rem 9 1/2 was the smallest diameter of anything I measured. I was at least .001- ,0015 smaller than some stuff.

I usually start with it when messing with regular stuff as I know when the pockets finally get loose, I can switch to something else and have tight pockets. Also, my very unscientific testing leads me to believe that Rem 9 1/2 are the mildest primer I have, WLRM are the hottest and Wolf have the hardest cups.

Don't know if you guys have found similar.