Peculiar range performance

[strut64]

I have been working with a rifle that has a Shilen 8 twist barrel chambered in 6BR Norma. When I start a session, the rifle shoots erractically. About 3/4" +/-. After 6 or 8 shots it settles down and shoots great groups. I have just realized what it was doing when I was frustrated by erratic groups when shooting what I thought was proven loads, and I would quit shooting. Recently I added a Redding bushing die and KM neck turner. I then started shooting lengthy range session to evaluate the benefit. I got repeatable results over a number of range sessions. Anyone else see similar behavior? Is it warming or fouling? I don't clean after every session but often after a 100+ rounds. I know that if I do a thorough bore cleaning, that the barrel requires fouling with a few shots.

 

[WyleWD]

Are you using naked or coated bullets?

You "often" clean after 100 rounds... seems like an awful lot to me with an 8 twist barrel. Typically most shooters that I know clean around 40-50 rounds whether it needs it or not. I interpret the "often clean..." statement to mean that you might go considerably over the 100 rounds too.

As far as the 6-8 shots to settle down, that seems pretty normal on a cleaned and unfouled barrel... maybe on the high side of what I would expect, but not necessarily too high. JME. WD

 

[DeltaBravo]

I had the same performance with my 8-twist 4-groove Shilen barreled rifle; same for my 14-twist 4-groove barrel. I always just planned on fouling with the first 5 shots while also getting a smattering of wind info. I clean about every 20-50 rounds, depending, but usually right at 25. Once both barrels settled down, they would/will shoot in the teens if I do my part. I got over 2000 rounds down the 8-twist and it still shoots; I've got 700 down the 14-twist and it shoots too.

Dennis