What is the difference?  I have a chance to buy an M99 that is about 3 years old with 20 rounds through it for $2500.

Edit.  I guess the a1 has a shorter, fluted barrel.

If I remember correct, the biggest difference is the bolt and the number of lugs cut into the bolt and action.

They differ between the two models making it so that they are not interchangable.

The M99 and 99-1 have 21 locking lugs ala interrupted buttress threads. The 99-1 has the 29" fluted barrel. The 99 has a 33" heavy barrel.

The 99A1 rifles have a new bolt that only has 9 heavy lugs still in the buttress pattern. The lenght of pull is about 2" shorter. The trigger housing on the A1 was moved to the rear that much. The trigger housings of the 2 models will not interchange.

The A1 model has a 4140 rail with screws that secure it to the receiver. The 99 had the rail as an extrusion that was intergral to the receiver.

Totally off topic, but if you decide you do not want to buy the rifle.  I may take it.
Matt

I just brought it home.  (sorry Matt)  It's in perfect shape.  Now I need an optic.

The newer M99 models have a more effective muzzle brake, also, believe you can tell the diff in pix as three holes/slots versus two.

Quoted: I just brought it home.  (sorry Matt)  It's in perfect shape.  Now I need an optic.

AHHHH I cant find one.  How do you like it.  Have you shot it yet?  can I ask how much $$$$$$$$$ these things go for now?

I've got about 3k to throw at one.....Matt

It is very nice.  Well made and really simple.  I am going shooting tomorrow.  I paid $2500 and just got lucky and found it locally.  I had a Springfield Armory scope laying around from an M1A I don't have any more, so I mounted it.