I have a new rifle that shoots jacketed bullets very well ”€œ well under a MOA for five shot groups.
It also has shot cast very well at times. Two days ago I shot a string of nine five shot groups without cleaning that averaged .85 MOA using my 75-grain MOS bullet . At the end of that string there were flakes and slivers of lead on the first patch but the last group had been2.0 MOA (half an inch at 50 yards).
Since then I have been lucky to get five good shots before groups double and often the first group has one out that doubles the group. I get a lot of three and four shot clusters under .7 MOA and a few five shot groups in the .8 - .9 MOA range usually the first group after cleaning.
I was shooting 700X at about 1,300 ft/sec. and have since switched to 4759 at 1,400 --1,500 fps, which seemed to help. I have also switched to Remington small pistol primers which also seemed to help at first. The 3 alloys I have tried have been from 13 to 18 BHN. I plan to try linotype next but doubt I can seat them far enough to seal at the front band without using a hammer.
The bullet shape is similar to RCBS Silhouette bullets. When I extract a round without firing there are strong land marks and 100% seal on the front band. In fact I am now seating them a tenth of an inch longer than needed to get 100 % contact.
The last two groups I shot last night were with PVC wads. There may have been some improvement but there was a little lead on the first patch afterwards. I will try some more this morning but I have never gotten improvement with wads and they are a pain to fiddle with.
From the way a tight patch of lead out cloth is easier to push through the central part of the bore, I fear that there is a loose area in the middle of the bore, just like all the recent Savages I have had trouble with. I will slug it this morning to check but that is also where I clearly feel the resistance of the lead with the first patch - starting maybe six to nine inches ahead of the throat.
I am about at wits end with this problem. I would appreciate any suggestions about what could be causing this.
John