.243 AI - How fast is too fast

[IdahoCTD]

51-52grs of Retumbo works well in my 2 243AI's with 105 Amax's. The short barreled rifle runs 3250 and the longer barrel runs over 3300fps. Numerous rockchucks can attest to the effectiveness, ;D

 

[rchouser]

I believe I have about reached the top (I still can open the bolt, and while well flattened, the primers are not smeared across the primer pocket).

I am declaring myself at the top with 46.5 gr W760, 250 cci primer, 87gr VMAX seated at .010 off the lands in Lapua brass. This load is shooting at 3530 fps AVG VEL with a Very Decent SD and ED.

The reason I am declaring this the TOP for this rifle is NOT because I don't have room for more powder. It is NOT because I believe I am at a dangerous pressure level.

I believe I am at the top because the last full grain I added (up from 45.5 to 45.6 grs in two steps) only resulted in a velocity increase of 51 fps AVG VEL.

I have been getting a fairly even 48-49 fps gain per !/2 GR for the long march up. It took a full grain now to gain the last 51 FPS. I believe this about signals the end of the string for this powder/primer/bullet/brass combination.

Now the good news. Loading 46.5 gr W760 produces 3532 FPS AVG VEL. I am also finally getting the Little Teeny Tiny bugholes (only at 100 yds so far) that I have been hearing about.

I guess the 243AI really just needed the heat put to it. I havn't miked my brass webs yet to see what damage I might be doing to the brass, but, for now, I think I will just sit here and gloat. I have a load for the 87 gr VMAX. Now I have to order some more bullets.

I would appreciate opinions on shooting the 87gr VMAX at 3532 AVG VEL. This ought to smack the cr*p out of brother groundhog and sister fox. I suspect EXPLOSIVE terminal effects.

thanks to all that have been helping me. Please stay available because this is just the first adventure of an old guy.

rch

 

[Brians356]

I believe I am at the top because the last full grain I increased the load (up from 45.5 to 45.6 grs) only resulted in a velocity increase of 51 fps AVG VEL.

I have been getting a fairly even 48-49 fps gain per !/2 GR for the long march up. It took a full grain now to gain the last 51 FPS. I believe this about signals the end of the string for this powder/primer/bullet/brass combination.

Diminishing returns. I feel that is a sound and well-reasoned analysis. And as it shoots bugholes, what's not to like?