260 OAL Issue

[highcotton]

Started preparing to load some 130 AB's for my son's 260 last night. Lapua brass sitting on bench ready to load, so proceed to check OAL for the round. Measurement I took said 2.910 to the lands. I backed off 0.030, giving me 2.880 for a starting point. I still had a couple of 120 BT's loaded, and I'm not sure why, but I put one in the magazine and it just did fit. I had never noticed how close they were before. Here is the issue- they are at 2.812. I am planning to load these AB's to mag length now, but here is the question. If depth needs to be tweaked some based on groups, in what increments do I shorten them up? The rifle is a custom, Lilja barrel on a 700 action. Advice appreciated.

 

[skidmark]

2.910 ogive measurement ?

 

[highcotton]

2.910 was measurement from bolt face to tip of bullet dropped into chamber. Measured with a wooden dial rod, as I've done for all other load work for years.

 

[Songdog]

In a 700 Short Action I never go longer than 2.80" COAL.... that's the only way you'll get reliable feeding. I also shoot a .260 on a Rem. SA.... and like you, it bothered me that I was nowhere near the lands.... in fact, my 123 Amax loads are jumping over .10".

But, I've had excellent accuracy out of every bullet I've tried outta my 23" 1-8" Rock pipe at mag length. In fact, I don't think it has shot anything over an inch...

Here's a few groups, all at 2.8" COAL or shorter.

123 Amax (except where noted)...

100 yds...









130 AccuBond...



300 yds...





500 Yds...

 

[DrMike]

Those are certainly fine groups, SD. I'm going to have to get back to work on a couple of 260s very soon.

 

[highcotton]

Thanks for the info SD. I think I'll load the AB's at 2.812 (no feeding problems so far) like the BT's and see what they do.

 

[Songdog]

Thanks for the info SD. I think I'll load the AB's at 2.812 (no feeding problems so far) like the BT's and see what they do.

You don't see the feeding issues until you stuff the mag full... one round in the mag won't tell you the whole story.... I'm not guessing on this. There's a coyote out there, who's alive to tell the tale this day because of that... I shot is girlfriend twice... then he got a pass due to fail to feed.

 

[highcotton]

SD, noticed one of your loads on target was 44 gr W760. What's your load of choice for your 260? I have been working with IMR 4350, but have some W760 on hand.
HC

 

[Songdog]

I shot over 2 lbs of 760 in the .260 this summer... but that was because H4350 was impossible to find. It was very accurate, but you had to be aware of high temps causing some POI issues. I never really saw any pressure issues in the heat , just 100 fps or so increase when the temps were 90+.

Varget also shot very well.... as you can see by the 100 yard group and 500 yard groups that are both in the sub-1/2 MOA range. My only complaint about that powder was the velocity, it was about 100-175 fps slower than powders in the 760/4350 class .

Most of those groups are 44.4 grains H4350 and either a WLR or Fed 210 primer for about 2950 fps. The Accubonds were 41.3 grains IMR4350 for about 2800.

 

[highcotton]

Thanks for the info. I'll stick with the 4350 plan and see where it goes.