Kenny, since you brought up that you had looked at a couple of the Mag cases for 7mm, i did a recycle bin restore of the grey matter earlier on today.
JR and i both ran mini mag 7 mils for quite a number of years until we saw the light and went 30 cal
. Anyway JR went with the 6.5/350 Rem mag brass with their 2.170" cases and i went with the full 2.5" 7 Rem mag, then a shorter version at 2.25" and then finally 2.0". It was a toss up between the last two as to which was the better. The biggest limitation with any of these mini mags back then was brass life span. And we did try them all except for RWS.
If i was to do it over again, the only way i would do it would be with RWS brass, either 300 Win or 7 mag and form cases from them. The 2.25" case i used and the case JR used were about borderline overbore for the 7 mils, but both worked best with a guts full of 2209 which retrospectively was good because of the dramas we have had with humidity and slow burn rate powders. Ian Lampl did a mini mag 7 based on Rigby brass brought back to 2" and he also had very good results with 52-55 grains of 2209. 168 SMKs were pretty universal except i went off on another tangent with the very good 162 Amax batches in the early days. Not the Amax with the alloy insert, the newer polymer type.
Now JR will tell you that with what we knew, or rather didn't know back then, his 7 mini mag shot some of the smallest elevation at 1K we have seen till more recently. I reckon if this gun was still with Jeff, it would hold a number of the LG records. The down side again was the amount of work he had to do to keep the brass up to the gun aswell as the ever dwindling supply of that breed of cases.
Back then we looked at things differently to what we do now. Now a 6 or 25 is just a toy, though many would hold another view. The 6.5s should be in the hands of all our competition and the 7s and 30s are the choice for any serious contender. I agree that a 30 LG may be a little too much recoil for some and to keep that recoil down the projectile choice is often not the 200 or 220 SMK. Peter Henry has used both the big 30 cal pills in his 30/338 LG and does do well with it. Alan uses the 175s as does Bob Luther and they are a real force to reckon with on any day
So you're now left with the 7 mm. The pills to pick from for tight groups are with the 168 SMK and if you can find a good batch of 162 Amax like i used on the weekend they offer a .630 real world BC. The 168 Berger is very good but has an inflated BC that is just marginly better than the 168 SMK.
The 175 SMK is a hit and miss bullet that i have yet to work out what twist rate it should use. I have fired them on the same day in 9, 9.5, 10 and 11 twists and there was no difference in grouping, or lack of it at 500 M. What i do know about them is that they work reasonably well at 2800-2825 fps in a 9.5 twist. Three different batches and 800+ 175s down range in all types of cases and twists has not reproduced one group better than what i can get out of the 168 or 162. Eric G has shot one 3.xxx group at 1K with the 175 but went backwards with the aggs overall until he returned to the 168s. The consistancy with the 175 is just not there. This bullet had so much promise and early correspondence JR had with Dave Tooley led us to believe that this was to be the holy grail of 7 mils. Later it was to come out that the developement on the 175 Tooley had done, point up dies and all, was that he used a polymer nose insert, as he does in his BIBs, giving him a very high BC and good accuracy out of his 9 twist 280 AI. What
Sierra came out with is a totally different bullet. Why? Who knows.
Forget what the box says, the Amax working range is 2900 through 3100 in 9.5-10 twist barrels and can reliably go sub 2 inch at 500 and can nudge the 1 inch in good weather. The 168s, both Sierra and Berger can also do this in 10 twist barrels. The 180 Berger is too fickle to be a contender in all weather and requires at least a 8.5 twist or faster to work, so i relegate this combination to the same category of the 6.5s; 4 good shots and one off to the moon. Way too many rpms.
So you now have the bullets, 168 Berger and SMK and the Amax. For a barrel and twist rate i reckon a 9.5 Krieger or 10 Maddco. The speed you need is 2900 plus. So the case choice comes down to what will do this 2900 fps and not lose a primer pocket in a couple of shots. The cases worth the effort are 270/280 RWS, 9.3x62 Lapua in standard size, and in mag size the RWS anything and Lapua 300 WinMag. The case design won't matter that much, around 70 grains H2O in volume, 30/35/40 degree shoulders don't matter that much, a long neck helps as i said earlier. The mag cases may need quite a bit of work to get to 70 grains of H20, but if the brass is good a 100 should see out the life of the barrel. A full length 7 Mag like the Rem will work fine, but the barrel erosion is a bit high. A longer necked version may extend this a little.
Tony Z.
starting up 600 this year, put a good amount of thought in the wind flags as they are what gives you the groups and scores, not barrels, cartridges or high BC bullets. The NRA range flags are only just basic and once wet from the rain, you may aswell stick your dick out on the bench.
