BAT Model B in 6mm Dasher Rifle Project

Project Completed April 7, 2010

The first 6 Dasher built on a trued Remington 700 action performed so well that it was time to build a dedicated midrange target rifle in the same caliber, on a BAT action. This rifle complements the BAT 6.5-284 that is used primarily for long range events. I chose a round Model B, right bolt, right port action for this rifle. I also chose the same Lowrider stock design, from West Custom Rifles, in order to keep the same tracking and ergonomics as the two other rifles in my F Class lineup.

The specifications for the rifle are as follows:

Initial Observations

4/7/10

The barrel stopped copper fouling after only 7 rounds. Groups at 200 yards were in the 0.5 to 0.7 inch range. This with a non-tuned load of 33.0 grains RL-15, CC450 primers, and 107 grain SMKs seated 0.010" back from a hard jam. I suspect that the lot of RL-15 is a bit slow, so a trip to the range to work up the correct charge weight is in order.

4/10/10

I entered a 500 yard F Class match with this new rifle. Even with the non optimized load (see above), the performance was spectacular. The first string was a 200-18x, on the standard 500 yard F Class target center. The final two strings scores were 200-9x and 198-11x, for a 598-38x. The 200-18x is a personal best at 500 yards. Too bad it was not a registered match, as it would have beaten the NRA record for 20 shots at 500 yards of 200-16x. I will still go and optimize the load for this lot of powder, but I seriously doubt that the performance can improve much. This is now the 6th Broughton barrel I have chambered and shot at mid and long range, and every one of them has been a shooter. My hat is off to Tim North at Broughton!

4/17/10

Today was spent at the range doing load development for this new rifle, all at 200 yards. In particular, the goal was to find out if the current lot of RL-15 I was using was in fact slower than previous lots. Five shot groups of Berger 105 grain VLDs were used for this testing.

The results were definitive: these newer lots (2009 vintage) are definitely slower than my previous lots. At 33.0 grains, the velocities were running about 2990, and the accuracy was good at about 0.4 MOA. (This is the load with which the F-Class match on 4/10/10 was shot). It took 33.6 grains to achieve 3070 FPS with this new lot of powder.

Once the load was optimized to achieve the 1.335 mS OBT at about 3070 FPS, the performance improved significantly. At 33.6 grains, velocities were right at 3075 FPS, with standard deviations around 3 FPS and extreme spreads about 8 FPS. Groups were in the 0.1s to 0.2s, with the 105 grain Bergers loaded 0.013" back from a hard jam:

This performance is extremely good, better than any of the other Dasher barrels I have had in the past. While this newer lot of RL-15 is a bit slower, there were no issues with achieving the 3070 FPS and the 1.335 mS OBT. The case was just about full at 34 grains, so if anything, loading density has increased a bit. With the velocity variations being so low, it is anticipated that this will be a super long range load. I plan to enter a 300 yard match next weekend using this load, and will log the results here.