In the winter I find that the first shot from a cold, dirty barrel (I rarely clean a 22lr barrel) using sub-sonic ammo' is always 0.5" high and 0.5" to the right (at 40 yards) compared to subsequent shots.

The gun, an Anschutz 1417 with a two stage trigger and 14" heavy varmint barrel, has been pillar bedded and I have fitted a silicone pressure pad at the fore-end tip.

Could it be that the action/stock interface is different after cold storage overnight and that the action re-seats itself after the first shot recoil ?

So, maybe this phenomenon is caused by poor bedding, any ideas ?

very common occurance with any rifle

quote:

Originally posted by butchloc:
very common occurance with any rifle

Well, if it's that common then the underlying cause should be well understood.

I gotta think the situation with the first shot out of a cold dirty barrel is caused by the bullet lube that remained in the barrel being hard, and the first shot softens it up so the rifle shoots like it ought to after that.

Don

quote:

Originally posted by DMB:
I gotta think the situation with the first shot out of a cold dirty barrel is caused by the bullet lube that remained in the barrel being hard, and the first shot softens it up so the rifle shoots like it ought to after that.

Don

Thanks for that. Your theory could well be true as I do not get this effect with a cold dirty barrel 17hmr and V-max ammo' - which is not lubed. I'll try and get some 22lr ammo' with less lube. Cheers ...

pisces --

.22LR is probably some of the dirtiest ammo on the market, both for the action as well as the barrel. At very least I would run a bore snake through the barrel at least once before shooting. Adding oil to the residual fouling will only compound the problem. You might also try different ammo as most rimfire rifles are very particular to various fodder. HTH.

-- ale

I came to the same conclusion as DMB. Doesn't seem to be too bad with copper wash ammo, but I don't know if any of it is Sub-sonic?

I am presently experimenting with different ammo' to see whether the wayward first shot with a cold, dirty barrel effect can be reduced/eliminated.

One thing I have noticed is that the elapsed time between "cold" shots seems to be a factor.

For instance, if I discount the first wayward shot then 5 subsequent shots taken over a 5 minute period are in one 0.5" group at 40 yards. If I allow one hour to go by and then start shooting again, with a cold dirty barrel, these shots are to the same mean point of impact (MPOI).

If I repeat this after another two hours I get the same MPOI.

But, if I store the gun with the same cold dirty barrel overnight then the first shot is away with the fairies.

So, elapsed time between shots also seems to be a factor.

quote:

Originally posted by pisces:

One thing I have noticed is that the elapsed time between "cold" shots seems to be a factor.

I have noticed similar things at ARA benchrest matches. Shrinking the target illuminates matters.

Aleaddict is right about 22's being dirty, but it would vary with type. Sunday my son was shooting Armscorp .22LR through his stock Marlin Mod 15YN, while I shot CCI Green Tag and Winchester T22 through my Ruger 10/22 with a Shilen stainless barrel. While I shot twice as many rounds through my rifle, the barrel was half as dirty when we cleaned the two rifles.

Different ammo, different barrels, or combination of both?

Probably only takes one shot to filthy up a barrel with flakes using SK or Lapua, but it doesn't seem to worry the groups. Hopefully it blows out each shot.

Back in college when I shot three position we would always quickly burn some "spotters" down the barrel at the start of the match. Sometimes, its not the first round which settles the rifle in.

The first shot from a clean bbl is also well documented. It occurs in a 22 when you change bullets and lube in other lead shooters. That is why your fouling shot should be the same type as your target loads. Gianni