New distance shooter from AZ

My name is Dennis, and I've been shooting since I was 7, back in '60. All sorts of different ones in and out of my 'collection', with a couple or 'never part with' originals my Dad gave me years ago.

Lately I've been attracted to distance shooting out to 800m, and so far the group is:

Steyr SSG-69 & AICS bottom metal w/S&B P series 3-12.

FN A3J HRT with the same optic. Not zeroed yet, too hot now.

A new Remington 700 police with a Magpul stock & bottom metal, awaiting a Thermion 2 XQ35 Pro I bought from Brownells for it.

I've had the Steyr for some time, and it has always been good to me, other than having to replace the Cycolac stock. The bottom kit is a real upgrade from original. All the above are in 308W.

I would like to add another suppressor to my stuff, this one for .30cal. Any recommendations for one set up for 5/8x24 threading?

Another question is will a can appreciably change POI? If so, is it distance dependent?

Thanks in advance for any advice.

SubRosa