Hi,
I just wanted to share a target with 6 keyholed boolits. It would be hard to reproduce such a perfect set of profiles!
The same boolit groups < 2" at 50 yds in the same rifle, so it's not a rifle, boolit, lube, or alloy problem. I changed a few things so I need to figure out which one is the culprit. Here are the specifics for the rounds that tumbled:
Rifle - H&R 38-55 Target Rifle
Boolit - Lyman 375449, gas checked
Alloy - WW
Size - .379
Lube - Bullshops Speed Green
Brass - Starline 38-55
Powder - 20gr and 21gr 2400
The thing that I changed from the "good" load was the brass and seating die.
The brass I used in the past was blown out 30-30 and .375 Win. The loading dies were .375 Win. The boolit was seated to where it lightly engraves. This leaves the last lube groove (without lube) seated out of the case. The groups are about 3-4" at 100 yds. with the issue sights.
The new batch of boolits that keyholed were loaded with Starline 2.125" 38-55 brass and a set of RCBS Cowboy dies. These were new cases and were not resized. Only the seater die was used. A light crimp was used. I loaded the rounds on a Dillon 550B so the expander die wasn't used. The powder funnel expanded the case enough to start the boolit without shaving any lead.
The overall length of the two loads was almost identical. It will be interesting to figure out what caused the difference in performance.
Any thoughts on what the cause will be?
John