Black Diamond 408
Well-Known Member
I got some of Richards bullets to test in my 338 Snipe-Tac, he sent 265gn and 300grn bullets. I dont think the 300's will work in my bbl so i didnt fire any of those yet.
I loaded up 6 rounds to sight in with at 100yds, the gun was sighted with 300MK's dead on. The first group was 2" high, about 1" three shots. I lowered the scope 2 MOA, next group was dead center but about 1 1/4" size.
Not what i was hoping for as the SMK bullets shoot in the low .2's. I figured the slower twist im using is causing the problem. The bullet holes are round so that was a plus. The initial loads were 145grns of H-BMG50, that produced 3500fps. The cases ejected easy but the primers were just a bit flatened.
I talked with Barney Lawton about my tests and he said if the holes were round then there prolly is a load that will make the bullets work. I pondered, maybe im driving them to fast? Sometimes 100yd groups are very decieving, what shoots good at 100 dont nessesarly shoot good at long distances, and visa versa. So i decided to do a long range test to see how the groups react.
I lasered a distance and set up a target stand, 703 yards. I loaded up three different powders, all are a bit different in burn rates. fastest to slowest,
US869....H-BMG50...WC872
I have used all three of these in testing with the 300MK, the 265 Alum tipped bullet has a long baring surface so the same loads were used to start with.
My gun loves WC872 with the 300MK, 143grns = 3300fps
Test rifle
Viersco stainless repeater action
Lone Wolf carbon stock
Lawton 33" 1-11.25 twist bbl
30moa base
IOR 6-24x50 35mm tube scope
---------------------------------
I loaded up three 143 WC872
Testing:
Average speed, 3400fps
SD 16
Group size 703yds 7"
--------------------------------
Next test group
140grns WC872
Speed 3337
SD 9
Group size 703yds 6"
--------------------------------
H-BMG 50 powder
140grns
Speed 3407
SD 18
Group size 703 6"
--------------------------------
H-BMG 50
142grns
speed 3450
SD 9
Group size 703yds 4.5"
--------------------------------
US869 powder
140grns
speed 3437
SD 3
Group size 3.2"
----------------------------------
The faster burning powders seemed to do a better job accuracy wise. Several groups were at or just under 1/2 moa at the 703 yard target.
All loads were tested with TTi armory brass.
The Exbal program was very close in predicting the needed MOA, tests ranged from 7 moa to 8moa, depending on the load used. Every test shot found the target, it was a 2 foot square target board.
I also tested the accuracy of my small chrono vs the Ohler 34, They were with in 8-10 fps on every shot.
My next test i will set up the chrono at 700yds and see what the speed is at that distance.
there will be some test results coming with a faster twist barrel and the 300grn AT Wildcats.
Dave
I loaded up 6 rounds to sight in with at 100yds, the gun was sighted with 300MK's dead on. The first group was 2" high, about 1" three shots. I lowered the scope 2 MOA, next group was dead center but about 1 1/4" size.
Not what i was hoping for as the SMK bullets shoot in the low .2's. I figured the slower twist im using is causing the problem. The bullet holes are round so that was a plus. The initial loads were 145grns of H-BMG50, that produced 3500fps. The cases ejected easy but the primers were just a bit flatened.
I talked with Barney Lawton about my tests and he said if the holes were round then there prolly is a load that will make the bullets work. I pondered, maybe im driving them to fast? Sometimes 100yd groups are very decieving, what shoots good at 100 dont nessesarly shoot good at long distances, and visa versa. So i decided to do a long range test to see how the groups react.
I lasered a distance and set up a target stand, 703 yards. I loaded up three different powders, all are a bit different in burn rates. fastest to slowest,
US869....H-BMG50...WC872
I have used all three of these in testing with the 300MK, the 265 Alum tipped bullet has a long baring surface so the same loads were used to start with.
My gun loves WC872 with the 300MK, 143grns = 3300fps
Test rifle
Viersco stainless repeater action
Lone Wolf carbon stock
Lawton 33" 1-11.25 twist bbl
30moa base
IOR 6-24x50 35mm tube scope
---------------------------------
I loaded up three 143 WC872
Testing:
Average speed, 3400fps
SD 16
Group size 703yds 7"
--------------------------------
Next test group
140grns WC872
Speed 3337
SD 9
Group size 703yds 6"
--------------------------------
H-BMG 50 powder
140grns
Speed 3407
SD 18
Group size 703 6"
--------------------------------
H-BMG 50
142grns
speed 3450
SD 9
Group size 703yds 4.5"
--------------------------------
US869 powder
140grns
speed 3437
SD 3
Group size 3.2"
----------------------------------
The faster burning powders seemed to do a better job accuracy wise. Several groups were at or just under 1/2 moa at the 703 yard target.
All loads were tested with TTi armory brass.
The Exbal program was very close in predicting the needed MOA, tests ranged from 7 moa to 8moa, depending on the load used. Every test shot found the target, it was a 2 foot square target board.
I also tested the accuracy of my small chrono vs the Ohler 34, They were with in 8-10 fps on every shot.
My next test i will set up the chrono at 700yds and see what the speed is at that distance.
there will be some test results coming with a faster twist barrel and the 300grn AT Wildcats.
Dave