Gentlemen,
I am new to AR, and let me just start off by expressing my awe at the expertise and helpfullness of your members. I have a full complement of big bores for hunting, including 2 505 gibbs; but now, I have been possessed by the desire to fire .510 caliber bullets (I have a large supply of fun projectiles, including spotter tracer and some Raufus rounds)
I am thinking about modifying a 30-378 Sako TRG which I had obtained for conversion to 338 lapua, to a 510 caliber cartridge. looking at the opinions of the AR members, the most practical conversion would be to 500 A square. Its not controlled round feed, but its going to be my "fun gun" where I can experiment with loads and bullets. For safari, i will use my 505's or 416. So here are the questions I have:
Is the conversion likely to work without too much effort? (I know the recoil lug on the sako trg is pretty flimsy, I will augment it). What barrel twist? I may be using 700+ grain bullets. What barrel diameter? (I like tapering barrels). What sights (I am partial to peep sights)And finally, what stock? I was thinking McMillan.
I hate muzzle breaks on hunting weapons (none of my rifles has one), but what about porting the barrel? And, since this a fun gun, perhaps a removable muzzle break as well? Does anyone know about a ported barrel with a removable muzzle break?
Finally, any recommendations for a barrel maker who can add a barrel recoil lug, and get the projectr done in a reasonably short time? My friend, Hugh Lomas from Elkhart lake, Wi, will be putting it together.

the 30-378 allows you the choices of
500 a2
510 wells
510 KX
550 express
550 magnum

if it was "merely" a 338 lapua, i would sugest the 500 AR

jeffe

I'm building a TRG right now and am adding a Remington recoil lug to the barrel. I'll use the original in the action also. McMillan's are nice, I'm using a Manners.

I wonder if the TRG's mag box is stout enough to withstand the recoil of a 500 A2.

I have a TRG-S in 338 Lapua that I'm slowly converting into a switch barrel, for the 416 rigby case head sized cartridges. This will let me play with a few different calibers for the price of the barrel and some machining. I haven't considered the 500, but I think i'll measure up the mags at home tonight and see if that will work. - dan

I have a TRG that has been converted to a 450 Ackley, love it!

Mike

I shoot a TRG-S in 338 lapua. Killed two groundhogs with it over the weekend. The stock has lug built into that mates to the action in a very solid manner. It is a fine rifle. I pretty much shoot 225 grain hornadys at 3050fps. I would hack up remington or rooger before I messed with my Sako. Triggers are great on that model Sako.

Gentlemen, thanks for the input. dan, good point; i will measure my magazine box also. 500 gr, you are right; but the 338 lapua is no slouch in the recoil department either, so i think the mag box will withstand the recoil. 390ish, I love Sakos also,I have 4, and I agree they are a better rifle than the others, but I have a "spare" TRG that i bought on sale just for the large action. My question now is, barrel dimensions. i am thinking of a 24 inch barrel, but what dia and taper? any ideas?