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.
for the rifle are as follows:
| 6mm Dasher
5C, 1:8 twist, stainless, 31" finished length, contour
1.250" straight cylinder
|Dave Kiff of
Pacific Tool and Gauge
– 6 Dasher, 0.272 neck, 0.110 freebore
Model B, right bolt, right port, 1.355" round
rail with 15 MOA offset.
Rifles Lowrider in Southwest Camo
Rutland laminate, with polished BAT trigger guard. Stock
has a Limbsaver pad, with about 1 pound of lead shot in
epoxy added to the butt and handgrip area to balance the
heavy barrel. Pillars are shop made from 303 stainless, with
a polished escutcheon on the bottom for the front screw. The
barreled action is bedded with Devcon 10110 epoxy.
Action screws are BAT for the 1/4-28 main screws, and
shop made for the 10-32 center screw.
NXS 12-42X56 with NP1-RR reticule
Leupold QRW high, 30MM
kg, or 20 lb 11.3 oz
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.
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!
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
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
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.