For you 7MM shooters:
I have an 7MM-330 Dakota, built off a Rem 700 action with a 27 inch Shilen Barrel in a 1:9 twist, with an IOR scope and McMillan stock. This gun shoots 0.25 - 0.5 MOA consistently with 140 grain accubonds at 3400 fps, and does not seem to be finicky with seating depth, but I get best results at 0.015 off the lands. I have wanted to try a bullet with a higher BC for long-range windage issues, so have tried the 160 grain accubonds and the 168 Berger VLD's. Neither one will shoot nearly as well as the 140 AB's --- the 160's are in the 0.5 - 0.75 MOA's, while the Bergers are all over - sometimes shooting 3-4 MOA groups. I have tried the Bergers at the lands to 0.025 off the lands with no obvious improvement, and velocity adjustment from 3000 to 3200 fps. I have had poor results with the Lost River J36 160's as well.
1. Do others have issues with the Bergers with this twist rate in 7MM?
2. Are their other high BC bullets I should try - ie Sierra MatchKings?
3. If I replace this barrel in the future - should I try a 1:8 twist?
Thanks for any input.
I'm shooting the Berger 180gr VLD at 3185 fps out of a 27" Rock barrel with a 1-9" twist chambered in 7mm RUM.
I shot 5-3 shot groups at 500 meters yesterday afternoon with an average group size for all 5 groups being .47 moa.
The smallest group was .23 moa and the largest was .61 moa.
This being said I think your twist rate is just fine, your barrel just might not like the 168gr Berger or you might want to try them with a .010" jam into the lands as this is what I'm doing with the 180's.
I also shoot the 175 SMK's at 2975 fps out of a 27" Broughton 5C barrel with a 1-9" twist chambered in 7mm WSM, they shoot real well, shot a 7.13" 15 shot agg at 1K earlier this month.
Hope this answers some of your questions,
Wayne aka WAMBO
Thanks for the reply. Did you do any testing with the seating depth off the lands? For hunting purposes, I would be less inclined to jam the bullet into the lands, just in case I had to unchamber the cartridge - would hate to leave a bullet in there or otherwise partially pull it out.
I seem to be having that problem also. I'm shooting a stock Rem 700PSS in 7mmRM. Using RL22/R9.5m mine shoots the 140TSX in to .4525" using 68.5gr @ 3234fps. I tried 69.0gr and velocity averaged 3297fps but accuracy went to .9570". Does anyone know what the max load is? I'm not seeing any of the obvious pressure signs. I may take it a little higher.
I've tried the 168gr SMK, 150gr NBT, 154gr SST and yesterday I tried the Berger 168gr VLD. The best of all these was the 150gr NBT at .3835" using 65.0gr of RL22/9.5M for average velocity of 3021fps! The worse was yesterday session with the 168gr Berger. I tried 63.5-65.0gr of IMR7828 with Fed LRM primers. Best accuracy was about 1.0" with the worse being 2.5-3.0"!! The powder's I've tried so far have been H4831SC/RL22/IMR7828. Primers have been CCI BR2/9.5M/215. I'm beginning to think this rifle likes the lighter range of bullets! I dunno but I ain't given' up yet. JohnnyK
"The only thing necessay for the triumph of evil is for good men to do nothing."
i am shooting a 7mm wsm 28 in broughton 5c barrel.i am loading 168 bergers at 3075. i was also having problems with mine until i started using h4831 and putting the bullet on the rifleling. i have now got my groups under .5. the bergers are great with the .64bc.
I haven't tried any testing with them off the lands as this is a target rifle.
I would try one of your cartridges with it .010" into the lands and see how it extracts, .010" isn't much and if you have sufficient neck tension you should be alright.
Wayne aka WAMBO
I have not had any luck with them. I am trying to shoot them in a .280AI with a 28in pac nor 1-9 with vv560. They appeared to be doing okay at 100 yards so I dialed up for 700. They shot about MOA. I was pretty dissapointed.
Tried jamming then jumping no matter what I did they shot MOA even though they shot in the .3s at 100.
I loaded some up for a buddy in his bone stock sps 7mag and shot a less than 1/2 MOA group with no tweaking, so I cant blame the bullets. Apparently my gun just doesnt like em either. Berger does make some fine bullets IMO wish it would have worked. Ditto for the accubonds in this gun, even though they shoot great in my 7rum. I guess I am stuck shooting the 140s.
I admit that I know just enough to be dangerous.....but dangerous at ever extending distances.