wildcat westerner
Well-Known Member
- Joined
- Nov 14, 2009
- Messages
- 680
After a long period ,the long barreled 338 magnum is ready to shoot , even though the rifle itself , is not finished yet. The first three tries to establish ballistics for the rifle were an inept failure. Three different times in three different locations with three different chronographs resulted in just two readings. It was absurd.
Finally, today we got another chronograph and suddenly we have some reliable data, for starters.
The rifle itself consists of a Stolle Tactical action which is free floated in the prone stock, even though it has a functioning magazine. We have utilized a 9 inch barrel barrel bedding block which still allows 22 inches of barrel outside the block to the muzzle. The barrel was one of two made for a Colorado rancher who had to take long distance shots at Elk on his property due to a deep valley which required a circuitous journey to get around, that included fording a creek. My barrel is a full 1 1/2" in diameter and was fluted by Skip Otto. It now has a radial muzzle brake made by Harrels' for prone shooting to avoid creating "Desert Storm II" when firing it from this position. The stock had to be lengthened, deepened and widened in the forend to provide balance when using the bipod. A NightForce scope is used.
I had several powders I felt would work with this rifle and also had a sufficient supply of 200 grain Hornady bullets that would do for testing light weight bullets in the rifle. They look like pistol bullets with a large flat nose and I was informed they were meant for the old .33 Winchester which started out as a black powder cartridge for the old 1886 Winchester lever action rifle. All I cared about was the fact they could hold together and actually make a round hole in the 100 yard target, even though going well over 1,000 fps faster then they were ever designed for!
I lacked target brass because none is made for this caliber. However, a good friend had over 700 cases and he carefully cur them all exactly the same length and weighed them and sent me the best, most uniform 50. Thanks Bill!
Thanks to QuikLoad, I had some basis to begin with as to estimation of potential velocities with a barrel this long. I chose : IMR 4350, 4831SC, MRP, RE22, Vit 560, H570 ,Vit. 165 and Retumbo powders. There are so many slower burning powders today I could have gone bankrupt trying them all,, but did choose N560 because Quikload felt that was a very good performer for this unique cartridge/barrel length combination.
I decided since I was in territory I had never been in before to use three methods of testing pressures: Tactile-by using just my little finger in raising the bolt handle to detect any pressures. I never detected any when testing all these loads. Visual- carefully noting any obvious over pressure signs on the fired primers, again no real obvious pressure signs on the Winchester primers I used. Lastly, I measured the case with a dial caliper, both before and after firing, ahead of the belt on the "Ring" left by the chamber on the case. If I had run into .001 expansion at this location I would have known I was in dangerous territory. Again, no expansion was noted on all the rounds I fired. A word about .338's in general. I have shot some very large rifles off a benchrest ( 416 Rigby's and a .458 Winchester) so recoil is not foreign to me. However, if I have a choice of firing a .338 and my larger .375 H&H magnum with its heavier bullets I would choose the 375 H&H every time! So the choice of creating this very heavy rifle in this caliber meant it would be more EFFICIENT than the others .338's I have gotten to shoot at Whittington ( 338 Edge, 33 Lapua and the 338 Lapua Improved). The last three were 30 and 40 pound weapons, and my rifle is about 25. Firing it is a lot more " friendly" than I suspected it would be , for over 80 rounds! This was over a protracted length of time.
Here are the results, so far
With three shot groups IMR 4350 averaged 3,067 fps at 70 grains, 3145 fps at 72 gr., 3,217 fps at 73 grains
4831sc averaged 3,054 at 75 grains, 3,107 at 76 grains and 3,127 at 77 grains
MRP averaged 3,318 fps at 80 grains, 3,367 fps at 81 grains and 3,376 fps at 82 grains
RE 22 averaged 3,017 fps at 73 rains, 3039 fps at 75 grains and 3,199 fps at 78 grains
Vit 560 averaged 3,155 fps at 77 grains, 3,179 fps at 79 grains and 3,210 fps at 81 grains
Vit 165 averaged 3,117 fps at 75 grains, 3,185 at 77 grains, and 3,230 fps at 78 grains
H570 averaged 2,719 fps at 75 grains, 2,784 fps at 78 grains and 2,889 fps at 81 grains
Retumbo averaged 2,832 fps at 75 grains, 2901 fps at 78 grains and 2,968 fps at 81 grains
As noted, the vast majority of rounds were over 3,000 fps. and showed no pressure signs whatsoever, so obviously I will be increasing the charges next time. When that test is complete, than I feel I can narrow my choices considerably as to powders and loads and then I will be starting to test to find out the potential accuracy of the 11 different bullets I have acquired that will best provide accuracy and proper expansion when this rifle will be used in early morning and late afternoon stands here in the Rockies.
Thank you,
WW
Finally, today we got another chronograph and suddenly we have some reliable data, for starters.
The rifle itself consists of a Stolle Tactical action which is free floated in the prone stock, even though it has a functioning magazine. We have utilized a 9 inch barrel barrel bedding block which still allows 22 inches of barrel outside the block to the muzzle. The barrel was one of two made for a Colorado rancher who had to take long distance shots at Elk on his property due to a deep valley which required a circuitous journey to get around, that included fording a creek. My barrel is a full 1 1/2" in diameter and was fluted by Skip Otto. It now has a radial muzzle brake made by Harrels' for prone shooting to avoid creating "Desert Storm II" when firing it from this position. The stock had to be lengthened, deepened and widened in the forend to provide balance when using the bipod. A NightForce scope is used.
I had several powders I felt would work with this rifle and also had a sufficient supply of 200 grain Hornady bullets that would do for testing light weight bullets in the rifle. They look like pistol bullets with a large flat nose and I was informed they were meant for the old .33 Winchester which started out as a black powder cartridge for the old 1886 Winchester lever action rifle. All I cared about was the fact they could hold together and actually make a round hole in the 100 yard target, even though going well over 1,000 fps faster then they were ever designed for!
I lacked target brass because none is made for this caliber. However, a good friend had over 700 cases and he carefully cur them all exactly the same length and weighed them and sent me the best, most uniform 50. Thanks Bill!
Thanks to QuikLoad, I had some basis to begin with as to estimation of potential velocities with a barrel this long. I chose : IMR 4350, 4831SC, MRP, RE22, Vit 560, H570 ,Vit. 165 and Retumbo powders. There are so many slower burning powders today I could have gone bankrupt trying them all,, but did choose N560 because Quikload felt that was a very good performer for this unique cartridge/barrel length combination.
I decided since I was in territory I had never been in before to use three methods of testing pressures: Tactile-by using just my little finger in raising the bolt handle to detect any pressures. I never detected any when testing all these loads. Visual- carefully noting any obvious over pressure signs on the fired primers, again no real obvious pressure signs on the Winchester primers I used. Lastly, I measured the case with a dial caliper, both before and after firing, ahead of the belt on the "Ring" left by the chamber on the case. If I had run into .001 expansion at this location I would have known I was in dangerous territory. Again, no expansion was noted on all the rounds I fired. A word about .338's in general. I have shot some very large rifles off a benchrest ( 416 Rigby's and a .458 Winchester) so recoil is not foreign to me. However, if I have a choice of firing a .338 and my larger .375 H&H magnum with its heavier bullets I would choose the 375 H&H every time! So the choice of creating this very heavy rifle in this caliber meant it would be more EFFICIENT than the others .338's I have gotten to shoot at Whittington ( 338 Edge, 33 Lapua and the 338 Lapua Improved). The last three were 30 and 40 pound weapons, and my rifle is about 25. Firing it is a lot more " friendly" than I suspected it would be , for over 80 rounds! This was over a protracted length of time.
Here are the results, so far
With three shot groups IMR 4350 averaged 3,067 fps at 70 grains, 3145 fps at 72 gr., 3,217 fps at 73 grains
4831sc averaged 3,054 at 75 grains, 3,107 at 76 grains and 3,127 at 77 grains
MRP averaged 3,318 fps at 80 grains, 3,367 fps at 81 grains and 3,376 fps at 82 grains
RE 22 averaged 3,017 fps at 73 rains, 3039 fps at 75 grains and 3,199 fps at 78 grains
Vit 560 averaged 3,155 fps at 77 grains, 3,179 fps at 79 grains and 3,210 fps at 81 grains
Vit 165 averaged 3,117 fps at 75 grains, 3,185 at 77 grains, and 3,230 fps at 78 grains
H570 averaged 2,719 fps at 75 grains, 2,784 fps at 78 grains and 2,889 fps at 81 grains
Retumbo averaged 2,832 fps at 75 grains, 2901 fps at 78 grains and 2,968 fps at 81 grains
As noted, the vast majority of rounds were over 3,000 fps. and showed no pressure signs whatsoever, so obviously I will be increasing the charges next time. When that test is complete, than I feel I can narrow my choices considerably as to powders and loads and then I will be starting to test to find out the potential accuracy of the 11 different bullets I have acquired that will best provide accuracy and proper expansion when this rifle will be used in early morning and late afternoon stands here in the Rockies.
Thank you,
WW
