Maven
07-16-2007, 05:26 PM
All, I had a chance to perform a rather limited test of the Lee group buy CB, but am hesitant to draw too many conclusions because of the test's brevity and some other factors, e.g., not having my cleaning rod on hand. I used LC match .30-06 brass with WLR primers to ignite 14gr. of Blue Dot. The 30-150-TL-PB's were unweighed and unsorted by cavity, but half were unsized and hand lubed with Lee Liq. Alox, the other half were sized to .311" and lubed with LBT Blue, which happened to be in my sizer. OAL was 3.125". The rifle is a Win. Mod. 70, glass bedded etc. The range was 50 yds.
Velocity: 14gr. B. Dot gave nearly the same results with sized & unsized CB's if I eliminated one high reading (1,647fps). The results below include that high reading.
Unsized (n = 13) Mean = 1,610; SD = 19, ES = 67fps
Sized (n = 15) Mean = 1,609; SD = 15, ES = 52fps
Accuracy: The sized CB's seemed to perform better in that I could get 5 to cluster in <1", but there was a great deal of scatter on the target (flyers?). The unsized ones did even worse, with no clustering of hits and greater dispersion on the target. As I didn't have my cleaning rod with me, I couldn't dry patch the bore for signs of leading. When I got home and cleaned the rifle, I discovered its presence. Ergo, the poor performance of the unsized CB's and frankly, the others as well, could have been due to leading, too much velocity, sizing "issues"* and even OAL.
Retesting is merited and will use a lesser charge of B. Dot or maybe 14gr. of WC 820, a longer OAL (~3.14" - 3.15") and possibly sorted CB's. Btw, none of my powder measures metered B. Dot very well. The Ly. #55 did better, but "better" is a relative term. My Ly. pistol powder measure's rotors were OK, but one through something like 13.5gr. while the other maybe 15.5. In retrospect, I should have used the lesser charge and the pistol powder measure.
*Sizing issues: I initially used the Lee push-thru die (.311"), but didn't like the job it did on this particular CB (all others have been fine). The Lyman #450 did a better job. Next time I'll use it exclusively.
Velocity: 14gr. B. Dot gave nearly the same results with sized & unsized CB's if I eliminated one high reading (1,647fps). The results below include that high reading.
Unsized (n = 13) Mean = 1,610; SD = 19, ES = 67fps
Sized (n = 15) Mean = 1,609; SD = 15, ES = 52fps
Accuracy: The sized CB's seemed to perform better in that I could get 5 to cluster in <1", but there was a great deal of scatter on the target (flyers?). The unsized ones did even worse, with no clustering of hits and greater dispersion on the target. As I didn't have my cleaning rod with me, I couldn't dry patch the bore for signs of leading. When I got home and cleaned the rifle, I discovered its presence. Ergo, the poor performance of the unsized CB's and frankly, the others as well, could have been due to leading, too much velocity, sizing "issues"* and even OAL.
Retesting is merited and will use a lesser charge of B. Dot or maybe 14gr. of WC 820, a longer OAL (~3.14" - 3.15") and possibly sorted CB's. Btw, none of my powder measures metered B. Dot very well. The Ly. #55 did better, but "better" is a relative term. My Ly. pistol powder measure's rotors were OK, but one through something like 13.5gr. while the other maybe 15.5. In retrospect, I should have used the lesser charge and the pistol powder measure.
*Sizing issues: I initially used the Lee push-thru die (.311"), but didn't like the job it did on this particular CB (all others have been fine). The Lyman #450 did a better job. Next time I'll use it exclusively.