Some experimenting with 260 Rem.

[bricktop]

Starting using the Hornady 123 AMax after others' recommendation to stay away from the heavies with this 6.5mm cartridge. I was using the Berger 140 LRBT, with limited success. The AMAX I think will also make for a good hunting bullet (white-tails inside of 400 yards).

Rifle is a R700 with a CBI prefit 22" stainless, 1.25"-0.9" (ish) straight taper in a Manners T5 with a Sightron SIII 6-24.

My main current interest was using AR-Comp, since there is little data available for it with the 260. I starting near the bottom with RL15 data, and also did a similar workup with trusty old H4350 for comparison. Brass is once-fired Lapua 260 trimmed to 2.025", primer was Wolf LR. Outside temp was 65 F.

Chamber is cut such that when the AMAX is at the lands, the COAL is about 2.850", or 2.267" Case-Ogive with my Hornady comparator. I loaded the rounds about 0.017" out at 2.250" C-O.

Here's the data (one shot each):

AR-Comp:
35.0 gr, 2688 fps
36.0 gr, 2754 fps
37.0 gr, 2807 fps
38.0 gr, 2842 fps
39.0 gr, 2923 fps (light ejector mark so I stopped here)

H4350:
42.0 gr, 2721 fps
43.0 gr, 2766 fps
44.0 gr, 2807 fps,
45.0 gr, 2917 fps
46.0 gr, 2982 fps (sticky bolt, light ejector mark - stopped here)

I hit 2900 fps okay with AR-Comp, so I was happy about that. If I can get a load that is accurate and has low ES at around 2850 fps I will be quite satisfied. If not, I'll work with the H4350. Sure to have some updates in the next few weeks.

 

[jcampbellsmith]

....Chamber is cut such that when the AMAX is at the lands, the COAL is about 2.850", or 2.257" Case-Ogive with my Hornady comparator. I loaded the rounds about 0.017" out at 2.250" C-O...

Good luck with that and keep us posted. In my rifle I get a measurement of 2.271 using the Hornady comparator on the 123 gr AMax, so our chambers must be very similar.

http://www.thestalkingdirectory.co.uk/gallery/member-galleries/p2948-remington-700-sa-in-260-rem.html

Regards JCS