Post by Richard on Feb 10, 2021 21:33:10 GMT -5
Trying some new combinations….
What with shortages of powders being a problem, I decided to try some older ones that I had on hand and revisited some 300 SST’s I had not shot in over two years. Last week I broke out the SST’s and thru my records and found I had not shot them since some time early in 2019 and that was with a 1-20 Brux barrel and was only launching them at 2800 fps. At the time, I was forced to put a wad under them in order for them to stabilize. So, I bumped them up to 2900 fps with 69 gr. of 4227 and up to 3050 with a 10/68 --- N-110/ H-4198 duplex……………without a wad! Low and behold, they stabilized and actually shot pretty well. But, only shot them at 100 yards because the wind was up pretty good.
This week, the wind was fairly quiet so I had them on my list to try at 300. I had the range to myself as both Herman and Bill could not make it. First I wanted to see how much adding a ½ grain more of 4227 (from 69 to 69.5) would do? Probably not a fair comparison because last week I was using the 300 SST with 69 grains and this week, I was using the 300 XTP with 69.5. It did however up the velocity form 2900 to 2913 fps. The ES was 12 fps. This was the first group out of a clean cold barrel.
I had been having good results with the 10/68 (110/4198) duplex, but wanted to see how different boosters would perform. On the burn rate chart, N-110, 4759 and 4227 are very close together so why not substitute them and see how they work. First, I used 4759 as my booster and got 3007 fps average with a 7 fps ES for five shots and landed them in .507”
Next, I substituted 4227 as my booster and brought the velocity up to 3036 fps with a 9 fps ES and a five shot .845” group.
Going back to the original N-110/H-4198 duplex my velocity was 3034 with another 9 fps ES. A four shot .365” and five in .847”. Pretty similar to the previous load. This week, with the XTP, my velocity was a bit slower as compared to last week using a SST.
For this final group at 100 yards, I switched to using 78 gr. of 2015 as my main charge with 10 gr. of N-110. The reason I upped the main charge to 78 was that it is a slower powder than 4198. The velocity was somewhat slower at 2973 and the ES larger at 18 fps. Group wise, it was also somewhat larger. This duplex might benefit from upping either the booster or main charge. I just happened to have a couple pounds of 2015 on hand and was curious as to what it might do.
Prior to moving out to 300 yards with the 300 SST and 10/68----110/4198 I took two sighter shots to see POI then up the elevation 4.5 MOA. (did not reset the Labradar for all 11 shots here) A three shot group went 2.325” and was somewhat high.
Lastly, I substituted the 300 AeroMax with this load and it put three in 1” four in 1.4” and all 6 in 2.4” The entire 11 shot string with two different bullets averaged 3046 fps with a 25 fps ES. probably play with it some more next week. (I know its an obsolete powder but I have a couple pounds and think I could probably find a few more if I did some searching. As a booster, it goes a long way.) The last six shots averaged 3041 with a 19 fps ES.
Seeing as how the duplex with 4759 as a booster produced such good results, I will play with it some more next week.
What with shortages of powders being a problem, I decided to try some older ones that I had on hand and revisited some 300 SST’s I had not shot in over two years. Last week I broke out the SST’s and thru my records and found I had not shot them since some time early in 2019 and that was with a 1-20 Brux barrel and was only launching them at 2800 fps. At the time, I was forced to put a wad under them in order for them to stabilize. So, I bumped them up to 2900 fps with 69 gr. of 4227 and up to 3050 with a 10/68 --- N-110/ H-4198 duplex……………without a wad! Low and behold, they stabilized and actually shot pretty well. But, only shot them at 100 yards because the wind was up pretty good.
This week, the wind was fairly quiet so I had them on my list to try at 300. I had the range to myself as both Herman and Bill could not make it. First I wanted to see how much adding a ½ grain more of 4227 (from 69 to 69.5) would do? Probably not a fair comparison because last week I was using the 300 SST with 69 grains and this week, I was using the 300 XTP with 69.5. It did however up the velocity form 2900 to 2913 fps. The ES was 12 fps. This was the first group out of a clean cold barrel.
I had been having good results with the 10/68 (110/4198) duplex, but wanted to see how different boosters would perform. On the burn rate chart, N-110, 4759 and 4227 are very close together so why not substitute them and see how they work. First, I used 4759 as my booster and got 3007 fps average with a 7 fps ES for five shots and landed them in .507”
Next, I substituted 4227 as my booster and brought the velocity up to 3036 fps with a 9 fps ES and a five shot .845” group.
Going back to the original N-110/H-4198 duplex my velocity was 3034 with another 9 fps ES. A four shot .365” and five in .847”. Pretty similar to the previous load. This week, with the XTP, my velocity was a bit slower as compared to last week using a SST.
For this final group at 100 yards, I switched to using 78 gr. of 2015 as my main charge with 10 gr. of N-110. The reason I upped the main charge to 78 was that it is a slower powder than 4198. The velocity was somewhat slower at 2973 and the ES larger at 18 fps. Group wise, it was also somewhat larger. This duplex might benefit from upping either the booster or main charge. I just happened to have a couple pounds of 2015 on hand and was curious as to what it might do.
Prior to moving out to 300 yards with the 300 SST and 10/68----110/4198 I took two sighter shots to see POI then up the elevation 4.5 MOA. (did not reset the Labradar for all 11 shots here) A three shot group went 2.325” and was somewhat high.
Lastly, I substituted the 300 AeroMax with this load and it put three in 1” four in 1.4” and all 6 in 2.4” The entire 11 shot string with two different bullets averaged 3046 fps with a 25 fps ES. probably play with it some more next week. (I know its an obsolete powder but I have a couple pounds and think I could probably find a few more if I did some searching. As a booster, it goes a long way.) The last six shots averaged 3041 with a 19 fps ES.
Seeing as how the duplex with 4759 as a booster produced such good results, I will play with it some more next week.