accuracy goes south

[jimr]

it seems like after about 40 or so rds my groups start to open up. i'm shooting lyman's 311672 wd-ww's sized to .310 in a FN-SPR-A1A .308 over 32.0 of IMR4895 with dacron filler with a c.o.l.of 2.750. lubed with Javelina Alox NRA formula with top grove left un-lubed, (which grouped best).
this load groups very well @100yds, 5 shots usually around 3/4" and 10 shots into 1in. @ 100. real close to 2100fps.
when i say open up i mean to about close to 2in. with the (J) bullet i usually can go several hundred till i notice a difference in grouping.
just wondering if this was about average. it doesn't take much to clean, 3 wet patches followed by 2 dry and accuracy is back up again.

[Larry Gibson]

You are picking up some fouling is all which might be antimonal wash. You might try adding 2% tin to your COWWs for a better alloy. You also are finding out that, contrary to some consensus here, that a "seasoned" barrel doesn't always shoot better than a clean barrel.

Larry Gibson

[chboats]

Some rifles/loads are like that. The same thing can happen with J bullets. You might try a different lube, it MIGHT help or the over all accuracy may go south. You never know until you try.

Carl