Ladder test interpretation 260

R

rrwildlife

Private
Full Member
Minuteman
Jul 22, 2013
19
0
Indiana
#1
Ok guys I need a little advice. The attached ladder test that was conducted this morning. They were shot side by side, in order, from 42.0-43.5 grains. One shot, of each load, on each targets then onto the next load. Temperature was 57 degrees, 65% relative humidity, and 30.29 pressure and 750 ft elevation. I was shooting a SAC 260 with a 21 3/4" Obermeyer barrel using H-4350 powder and 130 gr. Berger hunting VLD's loaded .010 off the lands. The range was 300 yards, with light wind <5 mph, shooting prone. All shots felt good except the 42.9 gr. load on the right hand target (although I would have called it high :( ). I'm not going to have a chance to recheck the loads before I head out. I know 43.0 grain shoots 1 hole groups in the low .3's at 100 (the result of load development before I could shoot at a greater distance). I need to pick one and be off with it, which one would you pick? I will be shooting the load at about the same elevation with temperatures ranging from the low 50's to the mid 80's.

I really appreciate any advice you can give.

Thanks

Ryan
 
#5
Thanks for the replies. Ya'll confirmed what I was thinking. I just wanted to make sure I wasn't missing something obvious. I have found it's usually good to have another perspective. I have not done much ladder testing was hoping I was on the right track.
 
#9
Ladder test interpretation 260

My advice: If you're shooting a .260 skip the ladder test and use a known load, like 43.5 or 44 H4350 with a 130gr bullet, and shoot that unless it isn't accurate at distance.
 
#10
You're over-thinking. Use the load that shoots well. On the off chance that velocity is all over the place and it won't shoot at distance, then cross that bridge when you get to it. A ladder test won't tell you that. In fact, it won't tell you much at all.

Put another way, instead of burning 12 rounds doing a ladder test, you could have shoot 2 six-round groups at distance with a load you know is accurate at 100. If there's vertical, it would show up. If not, you're done.
 
#11
Start with 42.3 and 42.6. I run the following.

42.2
42.4
42.6.
42.8

You're rifle shoots well enough that if possible, i'd shoot your ladders at a farther distance. Kind of hard to decipher your 300 yd ladder. I run my at least 600 to 660 yds.

Alan
 
#14
Graham,

what are some good "established" loads for the 140 gr vld...I'm having trouble working up a load, I'm starting at the rifling (2.910" C.O.L) with a 2.845" internal mag box so right off the start I'll have to either load super short or get an extended box. Also, at 2.910" my max load before compression with H4831 is 45.0 grs at 2600 fps with no pressure signs - Hornady book lists 47.0 as max at 2700 fps but I can't fit that much in the case and I'd like to get at least 2700-2750.

I'm thinking of trying H4831SC but I doubt I'll be able to fit much more in there. I don't really want to use RL17 b/c of it's temp sensitivity, I've had good luck with RL22 in my 7mm but I don't trust my chronograph enough to graph vel. vs temp, so my next choice is H4350.

And how do I decide what C.O.L to use before running the ladder test? Should I follow Berger's suggestion of loading several diff length cartridges 0.040" apart to see which groups best; if so, what powder charge do I start at. Or should I run the ladder first? Load development has always been a pain and these tests make it more complicated.
 
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