Hello all, I'm new to the forum and just started with the 6MM BR. I purchased a Salvage Model 12 with a 1/12 twist rate. I realize the bullet rate is critical to the twist rate but in order to shoot the rifle before I was set up to reload, I purchased a box of Laupa 90 grain bullets (All they had in stock). Imagine my surprise trying to zero the scope in at 25 yards. Seven bullets keyholed in the target. They entered at about a 60-70 degree angle. I didn't expect great accuracy but I also did not expect this. Is this normal for the twist rate vs bullet wt.?
Twist Rate vs Bullet Wt
- Thread starter Maxer5
- Start date
I ran the numbers for the 90 Scenar with a listed length of 1.108" (thanks Bryan Litz for your great book) and found with his included program that at 2900MV the 12 twist would have a 0.79 stability factor which is NOT stable. That barrel needs lighter bullets, for example the 70gr Sierra at 3200MV would have a 1.39 stability factor in that 12 twist which would be alright.
Maxer,
That's a bummer. I think my local shop has some of the lighter 6mm's on the shelf. I've got an 8 twist. I could probably shoot the 90's. For how hard it is to find what you want I'm sure someone would be willing to trade you. Your cost would be higher because you'll need to add in shipping, but hey we're helping each other. I'll need to check into it - if I can shoot them I'd trade you if you were interested in what I can get.
Take care,
Jeff
That's a bummer. I think my local shop has some of the lighter 6mm's on the shelf. I've got an 8 twist. I could probably shoot the 90's. For how hard it is to find what you want I'm sure someone would be willing to trade you. Your cost would be higher because you'll need to add in shipping, but hey we're helping each other. I'll need to check into it - if I can shoot them I'd trade you if you were interested in what I can get.
Take care,
Jeff
MarkS
Silver $$ Contributor
Maxer5,
I have 2 12 tw 6BR, the 80gr Berger's or any good custom made bullet. Any of the lighter benchrest bullets. For hunting varmints, I like 70gr Blitzkings. Any of these bullets will run with great accuracy past 600 yds, I have many one shot kill on Va grondhog past 500yds. A friend of mine killed a PD at 920 yds with 12 tw and 70 gr bullets.
Get you some 68 and 80gr Berger and you will be set.
Mark Schronce
I have 2 12 tw 6BR, the 80gr Berger's or any good custom made bullet. Any of the lighter benchrest bullets. For hunting varmints, I like 70gr Blitzkings. Any of these bullets will run with great accuracy past 600 yds, I have many one shot kill on Va grondhog past 500yds. A friend of mine killed a PD at 920 yds with 12 tw and 70 gr bullets.
Get you some 68 and 80gr Berger and you will be set.
Mark Schronce
Bullet length is the most critical factor.
Definately agree with Mark
68gn Bergs are quarenteed to satisfy and I would definately try a box of the 80 Bergs too. Go with the 68's first for a moral booster
I always start load development with Bergers .010'' into the lands past just touching. Its the "old Berger recommendation." Not always the perfect seating depth but usually close.
Lapua Scenars are usually very long for a given weight. Not surprised at your keyholing. The 12 twist just can't handle them. I've never had any 6mm Scenars.
Anyone have a length on them??
Definately agree with Mark
68gn Bergs are quarenteed to satisfy and I would definately try a box of the 80 Bergs too. Go with the 68's first for a moral booster
I always start load development with Bergers .010'' into the lands past just touching. Its the "old Berger recommendation." Not always the perfect seating depth but usually close.Lapua Scenars are usually very long for a given weight. Not surprised at your keyholing. The 12 twist just can't handle them. I've never had any 6mm Scenars.
Anyone have a length on them??
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