SHootSTraight22 said:
rchouser said:
I have a newly installed (75 rounds) 26" Bartlein 5r 9.0 twist barrel chambered in .243 AI. I have been working up to now 45.0 gr. of WIN 760 and a fed 215 primer. Using a jump of .010 I am getting the following (same load for both bullets):
87gr VMAX - avg vel - 3430 fps
75gr VMAX - avg vel - 3574 fps
I still have room in the case to up the powder, I am getting no sticky bolt and the primers are not smeared. I am not sure I see any point in going any higher in the velocity with these bullets, but, feel I have not reached the top.
What are you veteran 243 AI shooters getting with the 75 and 87 gr VMAX's. What is a reasonable "shooting" velocity for these in an AI.
Do you have any 105gr bullets to test.. I know your twist isn't perfect for the 105's but I'm interested in how much velocity you can obtain with them... I'm thinking about a 243 Imp 30 degrees to push 105gr accurately around 3,200-3,250fps if it can be done coated or not???
I have had quite few of the 243 AI customs, mostly Hart 1-12 twists that were Max heavy varmint weight, and long 27-30".
My hunting partner and I have probably had two dozen made off of minimum SAAMI spec reamer with turn necks. We shot Rem 7/08 brass, necked down.
Between his and my rifles, all Hart 12 twists, with zero freebore,
Fire form loads:
69-75g What evers
47.0-48.0g of Win 760 with a 70g TNT, 70g Nosler ballistic tip, 69g Berger
CCI 250 primer put Standard Deviation of 10 fps or less
3700-3750 fps
Groups .375 area
Formed load:
69-75g what evers
48.0-48.5g of Win 760
CCI250
3800-3850 fps
groups .250 area or less
Now, max loads in these barrels with the 70g Noslers was 50.5g of Win 760, with a Win mag primer, at 4030 fps, and cases needed to be full length sized after firing this load, but groups were in the .200 area
48.0-48.5 is a milder load for the lot numbers of powders, barrels, etc that we used, and we NEVER full length sized, NEVER.
When I kicked up the bullet weight to 85g, 45.5g of Win 760 with a cci250 was a max load with full length sizing needed after firing. What shocked me was that the 70g bullet at 3850 produced little copper fouling while the 85g copper fouled due to the extra bearing surface.
I would expect that a change from Rem to Lapua brass would eleviate any need to FL size for a few firings on those top end loads, but you need a reamer with a web dia of .472 to handle the Lapua brass. My reamer will not handle Lapua brass.
AA2700 proved to be very close to the Win 760 if not a duplicate on speed and accuracy with the same loads, but generated a tad more pressure, just a tad.
For 500 yard shooting, this is a hard round to beat with this velocity and flat shooting trajectory. We shot the head off of P. dogs at 300 with regularity.