Are there any special precautions I should use with this? I've been pretty careful with it since I got it to make sure everything fits in properly before shooting. I've heard that my barrel is going to lead up badly from the lead bullets, but in all of my regular rimfire rifles, running a boresnake through is all I really need to clean the bore. Is there any problem with lead in the gas system?

Also, fortunately the first time I went to shoot it, I was wearing safety glasses. It really sprays stuff out the back pretty bad. Is that a common thing with these?

Edited to add that I'm using it in a chrome lined M4 barrel.

I've read a few .223 rounds will clear your gas tube of crud from the .22 rimfire. I don't have a .22 upper, but it is what I've heard on these forums.

I have the Ceiner conversion for my BM XM15, and it works like a charm.  I use only the plated 22LR bullets, and run a few .223 fmj's every couple of hundred rounds of 22LR.  I have had no issues with gas problems, and have had no debris ejected rearward.  The only issue that I have had is making sure to clean the forward part of the .223 chamber, as my neck sized varmint ammo would not fully seat.  No prob. with factory FMJ's.  I would just suggest shooting decent 22LR ammo, not the cheapest, dirtiest that you can find.  Even premium 22LR is cheap, by comparison, and a whole lotta fun.

Craig

Thanks for the tips guys, exactly what I wanted to know.