The 109 is no arty piece. Think of it more along the lines of a long range greande launcher with a scope. Hence "Anti-Material Rifle". One man can't carry an arty piece and ammo on his back - mortors neither - but, one can carry the XM109 can his back and only go ask the nearest 20-mil GL-man to supply his with a few feet of link.
Now, go to the middle of this page and read from your rifle's picture to the end of the L115's article:
[link]The bottom, and I quote, says: "It’s an excellent cartridge, and the AWM sounds like a nice rifle, but the Taliban have a lot more cause to be afraid of the American Barrett M82, chambered in .50 Browning Machine Gun (12.7×99mm), which will reach out and touch someone even further and make a bigger hole."
Now, I believe that your weapon is in the top three. Bein' as the M82A1A and the new .416 Barrett are first and second---a very, very close first and second.
It all comes down to grain-count and the bullet's areodynamics (pardon me if I spelled that wrong-lol). The .50 has around 290-grain but not much aerodynamic to it. . . the L115A3's .338 Lapua (8.59mm) has a 250-grain count and a bit of aerodynamic to it. The .416 tromps both with a 400-grain count.
It doesn't come down to the weapon - it comes down to the bullet. Now, your record-holdin' SF Brit (or was he Canadian?) that made that .50 cal. sniper rifle only made his shot after he chambered an American-made .50 cal. round. We make both quality and quantity.
Overall the .50 M2 and the .416 Barret rounds will stay on top for the time bein'. The .338 Lapua (which we also make good sniper rifles for) comes in third. I don't mean to get into an arguement with anyone but, I do love a good match over sniper rifles.
All in good fun, yeah?