Texas Mac;   Thanks for the link to your article.  You pretty much covered the waterfront with it.

From discussions years ago with someone who worked for CCI, the difference was in the hardness/thickness of the primer cup itself.  Softer cup for pistol primers since handguns generally have less force available to transmit the firing pin strike to the primer compound.   

David

And here's a 'DMS' test of primer power done by Jim, owner of Cabine Tree Products:


This testing was done to try and rank primers by power (brisance).

This is the home made tester.  The shot is fired against a weight which in turn moves a pointer.  The pointer remains at the highest point of the shot.

This shows the pointer after a shot has been fired.  In this case, it was a Federal large rifle magnum

NOTE: This data is reference only.  This is on a DMS (don't mean squat) scale.  It is relative to this set of tests and this tester.  Take them with a grain of salt and as a guide only.  Most of the tests were of 100 or more primers.  A few were of 50 when limited amounts were available.
Ranked in order of power

Large Rifle = LR, Large Rifle Magnum = LRM, Large pistol =LP, 

Brand/type  Power Average  Range  Std. Dev

1 Fed Match GM215M     6.12    5.23-6.8  .351
2 Federal 215 LRM         5.69     5.2-6.5   .4437
3 CCI 250 LRM               5.66     4.5-7.4   .4832
4 Winchester WLRM        5.45     5.1-6.0   .2046
5 Remington 9 1/2 LRM   5.09     3.5-6.75 .6641
6 Winchester WLR           4.8       4.1-6.0   .4300
7 Remington 9 1/2 LR      4.75     3.7-6.25 .5679
8 Fed Match GM210M       4.64     4.0-5.6   .3296
9 Federal 210 LR              4.62     3.7-5.5   .3997
10 CCI BR2                       4.37    4.0-5.0   .2460
11 CCI 200 LR                   4.28    3.8-4.8   .3218
12 KVB 7 LR Russian          4.27    3.8-4.8   .2213
13 Rem 91/2 (30 yrs old)   4.16    3.8-4.8   .3

Quote:
Which one have you decided on Hank?

John Boy,
Think I saw that article somewhere and if I remember correctly, He also tested some pistol primers which showed considerably less power than the rifle primers. This assumes he was using the same scale.
Chuck

Chuck, sorry.  I forgot to post Cabine Tree's test of pistol primers using his same tester ...
Pistol primers
14 Rem LP                 4.47  3.2-5.6  .5171
15 KVB 45 LP Russian  3.89  3.3-4.2  .2232
16 CCI 300 LP             3.18  2.7-3.5  .2406
17 Federal 150 LP        3.11  2.6-3.5  .2090
18 Fed Match GM150M  3.05  2.6-3.7   .2299

Frank, have never seen or heard discussed the brisance of small pistol primers.  SWAG though ... Federal GM100M, the lowest, following in line with the other LP brisance ones