Post by Richard on Aug 29, 2017 21:36:47 GMT -5
A comparison of H I S to D I S
One of the objects of today’s shooting was to determine the ACTUAL difference in identical loads shot from the same gun at the same time or as close to “apples to apples” as possible. This will be shown on targets #2 and #3.
Except for long range groups 6 and 7, everything else is being shot with the 300 gr. Fury Star Tip bullets. No wads were used and primers in both systems were CCI LRMP’s.
Just a note to those unfamiliar with my calling of groups and sizes:
Sometime back 9 or 10 years ago a member on Doug’s (Harley) used to always indicate that any group ( of three or more shots) had to occur consecutively, or “in a row” to be considered a group. When I indicate a three shot group measured _ _ _ it could be shots 1.2 and 3 or 2,3 and 4 or 3,4 and 5 …………you get the point? I might list the “best of”………..Maybe 1, 2, 4 and 5 formed a good group but 3 was out so I would indicate that.
Starting off with a clean barrel you can see the first shot was 150 fps slower than the next four and it was out so I only counted a four shot group.
Here is where the comparison comes in! Using 88 gr. of AA2015 (which I had not shot in quite some time and using the DIS The five shot average velocity was 2884 fps with a 23 fps ES. I then removed the breech plug and installed the HIS breech plug and fired the same load. Here the average velocity was 2746 fps with a 16 fps ES. This was 138 fps slower than with the direct ignition and the load tended to string vertically. This might be corrected with upping the velocity with more powder. This powder seems to be more on the order of 3031.
Put back in the DIS plug and jump to 77 gr. of H-4198. If I eliminate the first shot (a powder switch) and I get an average velocity of 2884 with a low 7 ES and decent accuracy.
The last 100 yard group with the Fury’s came with 73 gr. of N-120. This load gave an average of 2887 fps with another low ES of 9 fps. Not sure why the fifth shot got out of the group as all shots were so close together in velocity but still a very accurate load from my rifle.
Prior to shooting the 275 AccuMax bullets at 300 yards (had not shot them for a while) I fired one shot at 100 to verify my POI (73 gr. N-120) So here my shot hit almost 2” high at 12:00……………..so in my mind I figured there was already 2 MOA built in. To this I added an additional 2 MOA and figured I might be a tad high? NOT!!!!!!
The accuracy of the load was phenomenal at ¾” but it hit 4” low of POA?? The only thing I could figure is that the Pittman needed an additional lighter to settle in. That one shot at 100 yards should never have been that high!
At this point I put my crosshairs on the bull and dialed down to the group (five clicks) and proceeded to shot another group using the same target. Quite a change from the previous group? We did have some wind kicking up which may have caused the larger dispersion but then again, the group went up higher than it should have? Its just one of those times when you scratch your head and say WT heck? While not super bad---3 shot is 1..5” and all five in under MOA, just not what I was expecting after the first group. What I was impressed with was the very low Extreme Spread in velocity for both groups or a total of 7 shots--------------14 fps!
So, DIS or HIS? They both work but the direct ignition definitely puts more fire in the powder. For a hunting rifle I would go with the HIS as it is more convenient. BTW, I had a ¼” long bushing from Hank that had opened up to .039” in the HIS plug.
One of the objects of today’s shooting was to determine the ACTUAL difference in identical loads shot from the same gun at the same time or as close to “apples to apples” as possible. This will be shown on targets #2 and #3.
Except for long range groups 6 and 7, everything else is being shot with the 300 gr. Fury Star Tip bullets. No wads were used and primers in both systems were CCI LRMP’s.
Just a note to those unfamiliar with my calling of groups and sizes:
Sometime back 9 or 10 years ago a member on Doug’s (Harley) used to always indicate that any group ( of three or more shots) had to occur consecutively, or “in a row” to be considered a group. When I indicate a three shot group measured _ _ _ it could be shots 1.2 and 3 or 2,3 and 4 or 3,4 and 5 …………you get the point? I might list the “best of”………..Maybe 1, 2, 4 and 5 formed a good group but 3 was out so I would indicate that.
Starting off with a clean barrel you can see the first shot was 150 fps slower than the next four and it was out so I only counted a four shot group.
Here is where the comparison comes in! Using 88 gr. of AA2015 (which I had not shot in quite some time and using the DIS The five shot average velocity was 2884 fps with a 23 fps ES. I then removed the breech plug and installed the HIS breech plug and fired the same load. Here the average velocity was 2746 fps with a 16 fps ES. This was 138 fps slower than with the direct ignition and the load tended to string vertically. This might be corrected with upping the velocity with more powder. This powder seems to be more on the order of 3031.
Put back in the DIS plug and jump to 77 gr. of H-4198. If I eliminate the first shot (a powder switch) and I get an average velocity of 2884 with a low 7 ES and decent accuracy.
The last 100 yard group with the Fury’s came with 73 gr. of N-120. This load gave an average of 2887 fps with another low ES of 9 fps. Not sure why the fifth shot got out of the group as all shots were so close together in velocity but still a very accurate load from my rifle.
Prior to shooting the 275 AccuMax bullets at 300 yards (had not shot them for a while) I fired one shot at 100 to verify my POI (73 gr. N-120) So here my shot hit almost 2” high at 12:00……………..so in my mind I figured there was already 2 MOA built in. To this I added an additional 2 MOA and figured I might be a tad high? NOT!!!!!!
The accuracy of the load was phenomenal at ¾” but it hit 4” low of POA?? The only thing I could figure is that the Pittman needed an additional lighter to settle in. That one shot at 100 yards should never have been that high!
At this point I put my crosshairs on the bull and dialed down to the group (five clicks) and proceeded to shot another group using the same target. Quite a change from the previous group? We did have some wind kicking up which may have caused the larger dispersion but then again, the group went up higher than it should have? Its just one of those times when you scratch your head and say WT heck? While not super bad---3 shot is 1..5” and all five in under MOA, just not what I was expecting after the first group. What I was impressed with was the very low Extreme Spread in velocity for both groups or a total of 7 shots--------------14 fps!
So, DIS or HIS? They both work but the direct ignition definitely puts more fire in the powder. For a hunting rifle I would go with the HIS as it is more convenient. BTW, I had a ¼” long bushing from Hank that had opened up to .039” in the HIS plug.
You want to play-----------------you have to pay! It is that way with any sport or hobby!
