I haven't had much time to work on this project, but I did get a couple of new bullets made and also a tapered sizing die that matches the throat.
They were supposed to be 180 grains and 190 grains but they dropped out heavier than expected. This shows the diameters after being sized in the taper die. Most serious benchrest shooters seem to use the tapered bullets fitted to a tapered throat, so I had high hopes that this would be a tackdriver.
Note that only the bottom 2 or 3 grooves were filled with lube. Normally I'm in the "more lube is better camp," but I wanted to try something different this time.
The bullets were only barely started in the case neck, then allowed to seat themselves the rest of the way when chambered. I'm told that works great if your case tension is just right, but today my case tension was nearly non-existent (I did not re-size the cases, merely decapped them).
In case you are wondering, the camera angle made the bullet bands look slanted. They're not really slanted.
56 gr. of WW760 ignited by a WLRM primer produced 2688 fps 15 feet from the muzzle. Standard deviation for 16 shots was 0.87%, which I consider a bit much for a rifle load.
Accuracy showed some promise while walking up the powder charge, but then the first 5 shot group was 23 5/8".
What the heck ? Usually when a load shoots patterns, either the barrel is fouled or else the bullet is getting damaged in the throat. There were no visible streaks of lead in the barrel, but there was a dry grey wash at the muzzle end. The grey wash was the same color as a cast bullet. I'm accustomed to seeing a wet, dark grey/black wash with hi-velocity loads, so I cleaned the barrel and the next group was 3.6" -- nothing to brag about, but at least it was a group, and the improvement after cleaning suggested that the barrel was indeed fouling.
So then I cleaned again, shot another 5 shot group which was 10", and two holes were oval shaped suggesting the bullets were tipping a bit.
Obviously this load had some serious problems so I did not bother shooting any more.What was different about this load that made it shoot so bad ?
-- less lube was applied
-- I did not size the cases, merely decapped them, so neck tension was non-existent and the "self-seating" feature may not have been working right. The bullets may have been seating too deep and not making firm contact with the rifling.
-- a radically tapered bullet that is more bore rider than loverin.Things to try next time
-- fix the next tension. I'm told that about 0.001" neck tension is ideal for target shooting. I'm told that it's a good idea to use either a neck sizing die or a collet crimp die. You can get away with not sizing the neck if the neck is turned to a perfect fit, but my neck turning is highly imperfect at the moment.
-- use more lube. Don't experiment with reduced lube until I have a reliable load.
-- try a deep seated 1-diameter bullet. I know everybody says deep seating is bad but I've usually had decent luck with loverins even when they had to be deep seated.
-- turn the necks for a better fit. I never did get my neck turning problems sorted out so that's part of the reason the neck tension was not right today.
-- anneal gas checks. My unannealed checks spring back to 0.309" when the bullet is sized to 0.3085". For consistent neck tension, the gas check should be the same diameter as the rest of the bullet.
-- I still haven't addressed the not-so-great trigger. It feels like 4 pounds.
There are many other experiments I'd like to do, but for now I need to focus on getting the basics right. This fitted neck business is new to me so it's going to take some practice. It's a good learning experience that will eventually allow me to better serve my customers.