.260 AI - Think I have got a load!!!!

I just shot a practice at 500, 600 and 1000 with my 260 AI and Sierra 142.

Short ranges were best with 47.5 or 48 gr 4831 SC. Long range was best with 50 gr RL22

RL22 test was 50 to 51 gr RL22. Velocity is about 3000

4831SC test was 47 to 48.5 of 4841SC. Easy extraction on all loads. Velocity about 2900 fps. (32" barrel) 47.5 and 48 were clearly the best groups, running around a half minute (10 shots)


In my experience 100 yards groups are fun, but do not predict down range accuracy at all. My minimum test distance is 300 and much prefer 500.

Today we had paid markers, so i could shoot a lot of ammo and then repeat at longer ranges. Results were about the same at each distance, with the 4831SC being slightly better at short range.
 
Magnum Peanut --

Using the Sinclair rest w/adjustable windage and an edgewood rear bag.....

Ganderite, I found the 142gr SMK didn't shoot nearly as well as the 139 gr Scenar.

Also, I find if a rifle doesnt group at all at 100, then it won't group at 300 or 500.

The last time I was shooting at longer ranges, I was fireforming brass with rl17 and 139gr scenars, and was getting 3 inch groups at 642 yrds, this was with 41.7gr rl 17, 139s hard jammed into the lands, I have no idea of speed, but it shot basicallly 1/2 moa. Im ok with that. The best guess for speed is 2700 and change or so.....

Brad
 
Too bad it doesn't like Sierras. Unfortunately, the Scenars have a mediocre ballistic coefficient in 6.5 (same with their 6mm!). Too bad because they work well. That would be a scary gun if you could make a 140 VLD perform like that!

I also agree with you completely on load development at 100.
 
Brad, what seating depth did you use for the group that started this thread. In the lands or off the rifling?

I just found a box of 1,000 of those Lapua bullets and want to load some for the ORA Annuals this weekend. I won't have a chance to test before the match. My 142SMKs work best about 20 thou off the rifling.
 
5 thou

off the rifling.

Thats what I was running on the 139gr scenars.


Obtunded, I have some of the 140 Berger VLD and the I think they are 140.5 LRBT.....

I am going to try the 140.5 bergers, but am not actively persuing changing the bullets, just have some loaded up to try here and there whenever I hit the range.........
Is not the "POSTED" BC somewhere around .615? (LApua) Most of the data I read says a true life .595 or so....

IF i ever get releases from the prison we all deal with ( A happy wife = a happy life) of landscaping/yeardwork :bangHead: I will post additional long range target pics.
 
The Brian Litz's Voodoo zombie actual BC of the Lapuas is actually only .557 (G1) whereas the Sierras are .588 and the Berger 140 VLD's are .612!.
 
Nice looking rig, what barrel contour did you use? The rifle doesn't look too heavy and she shoots just fine.
 
Its more complicated than that. Improved cartridges such as the 260 AI have a shoulder blown out to 40 degrees (from the 20 degree shoulder found on the 260 parent case) and the taper in the body is also blown out t little or nothing. It does provide more case capacity at the expense of neck length, and less propensity for smooth magazine feeding.
 
Thanx guys. I've been shooting a 260Rem since before commercial brass was available. Pretty happy with it, so it's still up to the jerk on the trigger.
 
300m target

Had some berger vlds out today, another batch of 142 smks, and some berger 140.5gr lrbt.



Had the 139 gr lapua scenars that the original post had which still was the best load, shot the last 3 I had in the box, would have liked to shoot some more, so back to the bench and back loading.


The SMKs were the same as before, all over, the vld bergers werent great either, close to 1.5 inch group, the berger 140.5LRBT was 2nd with 1.25 inch and heres the scenars..... Lots of vertical, but I am going to do a couple more groups... Is it the load or the clown behind the load..... We shall see.

260AIjpg.jpg
 
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