rojawe,
Good posting. Thanks.
It is interesting to me because Thunderbolts are one of the rounds that work in my SIG Mosquito -- but I only shoot about 50 to 100 rounds per session and clean with a bore snake.
I will be watching for this problem in my .22 rifles also. I have noticed that they do not feed well in my AR7 already. I still have a bit of Thunderbolts to go through. I got a "deal" on it before I got another "deal" on the bulk pack golden bullets.
BTW Federal and Winchester lead bullets FTF and FTE in my Mosquito. But we have discussed the Mosquito problems at length on an earlier thread.
I am still waiting to see what MB has heard from SIG about the problems. I for one will for sure wait to hear the answer before I invest in one of the new SIG .22 conversions.
Some one was saying that the Mosquito was made by some other Co. FOR Sig, Don't know how true it is. My buddy at Sig got fired

I some how doubt the ammo did that...
I don't THINK the guy took a crap in the barrel , and I don't know how else he would have got that much crud in there. From the video it sure looks to have the CONSISTANCY of fouling, my Buckmark gets the same type of crud after a coupke boxes,no where NEAR that extreme though.