All of my T8s are rated for 30cal, i use them on a .243 & .223 with no concerns. The last one came new with the .243 rifle as a combo so if the gun shop supplied it like that im sure there is no problem.
I use a 30cal A-Tec on my 270 and 243. I also have a 30cal T8 on my 223 you will have not problems, it might be a tad louder but unless you shot them side by side with a cal' specific moderator I doubt you would tell the difference.
like what all others are saying you should not hav a problem
the only thing i would worry about is :
(a) where from and why it is for sale
(b) was is specialy screw cut from a blank for a specific rifle as the thread may not match the one on your rifle
(c)how much cheaper is it than having new as sound mods get shot out quicker than than the rifle as a rule
not trying to put a downer on it but been down this road before
a good deal is good if it works a bad one will cost more than a new one in the first place
good luck in what you decide
ps i use t8 a little front heavy but tames my 3006 a treat
I have been told that the noise reduction may not be as good as with a cal specific mod, but so long as it is an improvement on the un-modded report and recoil then I will be happy. I guess it gives me flexibility if I decide to change calibre in the future
I buy my T8's from the guy who makes them in Finland. You should have no problems with a .30 cal T8 on 243. It is true to say that some folk dont like them, unbalances the rifle, looks ugly, they make a tinging noise. etc etc.
But for me they are one of the best things since sliced bread, just about all my mates have one or two on their shooting irons, and when it comes to novice stalkers and taking them out, with very little recoil and a good solid rest it makes it easier. I also believe it keeps the deer more settled and the ground itself.