I'm going to be getting and fn spr a1. I'm gonna put a shepherd 310p2 scope on it but I need to know what hight of rings to put on it. also any ideas on a good set of affordable tactical rings for it? i'm looking at liberty optics seekins precision, badger ordnance, or smith enterprises.

also I've read that these rifles don't do well with barrel mods like threading for a silencer. supposedly it messes up the harmonics because of the hammer forging? it dosn't make sense to me. what is the deal on that?

Medium rings ( I have the Shepherd 310-P2/ Med Leupold Tactical rings on my SPR A5M) I really like the setup...the Leupolds are approx 125.00
I dont know about the threading the muzzle part, But muzzle suppressors are going to change your point of impact..some suppressors have the ability to be indexed to find what suppressor orientation the rifle shoots best with. So its not just the barrel in the equasion.

Quoted:
Medium rings ( I have the Shepherd 310-P2/ Med Leupold Tactical rings on my SPR A5M) I really like the setup...the Leupolds are approx 125.00
I dont know about the threading the muzzle part, But muzzle suppressors are going to change your point of impact..some suppressors have the ability to be indexed to find what suppressor orientation the rifle shoots best with. So its not just the barrel in the equasion.

Ive read in one police department review that when the barrel on thier fn spr was shortened and threaded that they could no longer get sub moa groups with the rifle. the work was done by a professional and a poor crown job wasn't the problem. the gunsmith ended up putting a remington 700 barrel on it and it shot well again.

http://www.snipercountry.com/InReviews/FNHUSA_SPR.asp

Well, another factor is the FN SPR's have a chrome bore....700's don't.  FN don't advise you to cut off a barrel with a chrome bore.(as it can chip, resulting in less than happiness in the accuracy dept.) In fact they are flat against it(just call and ask them)