While my main purpose was to start building a load for my 338 RUM, I noticed on Hodgdon's reloading center that Win 780 and IMR 7828 (that is identified for the 338) are also published for the 243 Winchester. I wanted to compare it to my Nosler factory 87 grain partition which shoots 0.8 MOA. And since I had some Alliant RL 17 it was included into the mix.
Rifle is a 243 Winchester configured in a 1964 Browning Safari having a walnut stock with a free floated 22 inch barrel and a twist of 1:10; Browning bases and rings were used along with a Nikon A0 6.5x to 20 scope.
One case was selected and two slits were made in the neck and a bullet was inserted and slowly closed into the chamber. The bolt then was opened carefully and the case/bullet removed. This is supposedly the point of bullet touching the lands which was a COAL of 2.6995 inches. Berger's web site states that this bullet is not seating depth sensitive so a depth of 0.01 off the lands (about average range in the literature from 0.005 to 0.066) which gave good seating stability, no compressed charges and still functioned in the magazine.
All testing with powder was started at 0.5 grains less than the maximum load and then 3 grains in 1 grain increments for testing. For example, the maximum listed for Win 780 is 48.0 grains and testing started at 45.5, 46.5, and 47.5. If a good load was identified for example 46.5 then another test was conducted at 46 and 47 grains to see if there was any improvement. Accuracy was predominant over velocity.
Brass used in the testing was Nosler custom. The bullet used was Berger's 95 grain hybrid hunting bullet with an advertised G1 BC of 0.427 and 1.07 inches length. Primer used was Winchester Large Rifle. The bullet was seated half way into the case and then rotated 180 degrees to help with keeping bullet run out minimal. Run out was measured with Sinclair concentricity gauge and anything greater than 0.002 was rejected.
All testing was done at 100 yards using Bald Eagle match rest and "Protektor (brand name) leaf back rest. Groups with no vertical difference were preferred. If, for example, there were two identical groups but one was vertically distributed and the other horizontal, the horizontal was selected as the best load. Three shot groups were used in testing except when changing powders a fouling shot was included.
At testing Win 780 gave a good hunting group of 1.0 MOA at 45.5 grains. Upon testing IMR 7828, at 44 grains a 0.7 MOA was produced and testing at 45 grains essentially produced a 0.4 group and it was obvious this rifle likes 7828. For RL 17 results were at 40.5 grains a 0.2 MOA group was produced (Fig 1). This group was essentially repeated in another testing where the temperature was 50 degrees cooler using 4 shots (Fig 2). The rifle likes RL 17 slightly better than 7828. This load was then chronographed and came in at 2966 fps. Alliant RL 17 was selected as my go to load.
Rifle is a 243 Winchester configured in a 1964 Browning Safari having a walnut stock with a free floated 22 inch barrel and a twist of 1:10; Browning bases and rings were used along with a Nikon A0 6.5x to 20 scope.
One case was selected and two slits were made in the neck and a bullet was inserted and slowly closed into the chamber. The bolt then was opened carefully and the case/bullet removed. This is supposedly the point of bullet touching the lands which was a COAL of 2.6995 inches. Berger's web site states that this bullet is not seating depth sensitive so a depth of 0.01 off the lands (about average range in the literature from 0.005 to 0.066) which gave good seating stability, no compressed charges and still functioned in the magazine.
All testing with powder was started at 0.5 grains less than the maximum load and then 3 grains in 1 grain increments for testing. For example, the maximum listed for Win 780 is 48.0 grains and testing started at 45.5, 46.5, and 47.5. If a good load was identified for example 46.5 then another test was conducted at 46 and 47 grains to see if there was any improvement. Accuracy was predominant over velocity.
Brass used in the testing was Nosler custom. The bullet used was Berger's 95 grain hybrid hunting bullet with an advertised G1 BC of 0.427 and 1.07 inches length. Primer used was Winchester Large Rifle. The bullet was seated half way into the case and then rotated 180 degrees to help with keeping bullet run out minimal. Run out was measured with Sinclair concentricity gauge and anything greater than 0.002 was rejected.
All testing was done at 100 yards using Bald Eagle match rest and "Protektor (brand name) leaf back rest. Groups with no vertical difference were preferred. If, for example, there were two identical groups but one was vertically distributed and the other horizontal, the horizontal was selected as the best load. Three shot groups were used in testing except when changing powders a fouling shot was included.
At testing Win 780 gave a good hunting group of 1.0 MOA at 45.5 grains. Upon testing IMR 7828, at 44 grains a 0.7 MOA was produced and testing at 45 grains essentially produced a 0.4 group and it was obvious this rifle likes 7828. For RL 17 results were at 40.5 grains a 0.2 MOA group was produced (Fig 1). This group was essentially repeated in another testing where the temperature was 50 degrees cooler using 4 shots (Fig 2). The rifle likes RL 17 slightly better than 7828. This load was then chronographed and came in at 2966 fps. Alliant RL 17 was selected as my go to load.
