7mm-08 has significantly more velocity with same bullet weights than the CM, with the capability of much heavier projectile, should one wish. And since BC doesn’t matter to 90% of shooters, I get a kick out of the CM fanboy-ism.
P
The engineer in me got curious how the 6.5CM, 6.5PRC and 7mm-08 compare using mid-range bullet weights. Checked the ballistics using 6.5mm 129g and 142g LRAB and 7mm 140g AB and 150g LRAB. Used 7000ft altitude (my default) and MPBR zeroing for 6” diameter targets, Hodgdon load data for each weight, even if Hodgdon specified a different bullet. Used 130g bullet weights were data was not available for 129g and similarly used 143g data for 142g bullets. B.C values were taken from Nosler web site.
Also threw in data for a .280 Rem, which has a SAAMI MAP of 60,000psi, using a 155g Federal Terminal Ascent, since I’m working up loads for my .280 Rem. Federal load data, B.C. .586.
B.C. values used:
.530 = 6.5CM 129g LRAB
.625 = 6.5CM 142g LRAB
.485 = 7mm 140g AB
.546 = 7mm 150g LRAB
.586 = .280 Rem, 155g Terminal Ascent
Here is the load data (all with 24” barrels):
6.5CM, 129g LRAB @ 2889fps
6.5CM, 142g LRAB @ 2814fps
7mm-08, 140g AB @ 2976fps (no 7mm LRAB under 150g)
7mm-08, 150g LRAB @ 2908fps
6.5PRC, 129g LRAB @ 3090fps
6.5PRC, 142g LRAB @ 2982fps
.280 Rem, 155g TA @ 2949fps
And the results ==================
MPBR Zero:
250yds = 6.5CM/129g LRAB
247yds = 6.5CM/142g LRAB
256yds = 7mm-08, 140g AB
252yds = 7mm-08, 150g LRAB
267yds = 6.5PRC, 129g LRAB
260yds = 6.5PRC, 142g LRAB
256yds = .280 Rem, 155g Terminal Ascent
Drop @ 600 yds:
56” = 6.5CM, 129g LRAB
57” = 6.5CM, 142g LRAB
53” = 7mm-08, 140g AB
54” = 7mm-08, 150g LRAB
46” = 6.5PRC, 129g LRAB
48” = 6.5PRC, 142g LRAB
51” = .280 Rem, 155g Terminal Ascent
Wind Drift @ 600 yds:
18” = 6.5CM, 129g LRAB
15” = 6.5CM, 142g LRAB
19” = 7mm-08, 140g AB
17” = 7mm-08, 150g LRAB
16” = 6.5PRC, 129g LRAB
14” = 6.5PRC, 142g LRAB
15” = .280 Rem, 155g Terminal Ascent
2000fps:
730yds = 6.5CM, 129g LRAB
795yds = 6.5CM, 142g LRAB
725yds = 7mm-08, 140g AB
765yds= 7mm-08, 150g LRAB
875yds = 6.5PRC, 129g LRAB
940yds = 6.5PRC, 142g LRAB
855yds = .280 Rem, 155g Terminal Ascent
1500fpe:
475yds = 6.5CM, 129g LRAB
600yds = 6.5CM, 142g LRAB
565yds = 7mm-08, 140g AB
650yds = 7mm-08, 150g LRAB
620yds = 6.5PRC, 129g LRAB
750yds = 6.5PRC, 142g LRAB
765yds = .280 Rem, 155g Terminal Ascent
1000fpe:
850yds = 6.5CM, 129g LRAB
1040yds = 6.5CM, 142g LRAB
905yds = 7mm-08, 140g AB
1030yds = 7mm-08, 150g LRAB
995yds = 6.5PRC, 129g LRAB
1185yds = 6.5PRC, 142g LRAB
1170yds = .280 Rem, 155g Terminal Ascent
My thoughts ==================
If you are hunting smallish big game like antelope or limiting your shooting distances to 400 yards or under, you would need a microscope to tell the difference between the 6.5CM and 7mm-08. If going for larger game I might go with the heavier bullets offered by the 7mm-08. The 175g LRAB does very well, maintaining 1969fps/1500fpe out to 675yds with 70” drop and 16” wind drift at 600yds (2593fps M.V. per Hodgdon load data).
The 129g ABLR is still very capable at 600 yards, with 2145fps and 1318fpe. That is very similar to many .30-30 loads at 100 yards. The 6.5CM and 7mm-08 with bullets weighing 150g and less are both marginal for elk at 600 using my standard metric of 2000fps/1500fpe for elk, although I would prefer the 7mm-08. Or the 6.5PRC with the 143g bullet.
Love my .280 Rem.
