Ladder test ???

[tstarky]

Hi,
Spent today ladder testing a Remington XCRII 7mm Rem Mag, fairly new 200 rounds through it incuding break in rounds.
????? The ladder test gave unexpected results. ????? See images.
Large orange bullseye is 3" dia.
Shot 3-5 fouler/site in rounds for each ladder prior to each ladder test. Increased the powder charge progressivly by increasing 1/2 grain. i.e. shot 1= 54gr., shot 2= 54.5gr, shot 3= 55gr etc. See the pictures for specififications.

The ladder tests were shot prone with a led sled at 500 yards. 0-3mph wind. Scope is a Vortex Viper PST.
Brass is Winchester preped to match grade. Wilson dies used for neck sizing and seating. Powder weighed on 2 seperate, good scales for each round.

Why is there no progression up the vertical? Most of these "ladders" look like large groups. Any suggestions for finding the right bullet/load for this rifle?

 

[Gunpoor]

The target, shots 9 and 10, with the 168 VLD and IMR4831 got my attention! I think you have more than a little sign of consistency going there. If I were doing this I would load up five of each of these charge weights and shoot for group and see what they will do. As far as where bullets hit, that is just the physics of barrel harmonics and usually there is no rhyme or reason to it as far as where they hit vertically. Hope you achieve what you are the results you are looking for.

 

[steever]

I have an xcr II. In a .280 rem. I found with each load I tried during devlopment two shots would group great and 3 4 5 and on would walk away from the group, each group or test load would impact a different area of the target area. After a week of testing I purchased a new stock with a full aluminum bedding block and started over. With in a day my consistency came way up on a 5 shot group, my over all groups all came together into the same quater of the target, one I found my load I had a single ragged hole shooter, something I don't think I could do with the stock stock. So I would look into a stock before continuing load devlopment, but that's what I would do.. There is great potential there as your targets show, but I believe there is much more with a little better stock. Good luck with your shooter,
Steever

 

[RockyMtnMT]

Did you use the chrono to see where you were with each shot? This will help find a node as well, and tell you more about your pressure. Then you can pick you best and work on seating depth.

Steve

 

[RockyMtnMT]

RE 22 looks good at shot 7.

Steve

 

[jsthntn247]

I'd say 7,8,9 on your re 22 and imr 4831 with the 160's. Shots 12,13 look good with h4831 and 160's. I would concentrate on re22 and imr4831 with 7,8,9, you were getting almost no vertical at 500 yards over a 1.5 grain difference. That's about as good as it gets.

 

[tstarky]

Hi All,
I considered piller bedding and freefloating the barrel, or buying a good stock but wanted to see what kind of shooter I could coax this factory rifle into first, then add the improved or new stock and see what effect that has, then hopefully tighten the group by adjusting jump. Any stock suggestions, I like the McMilllan and HS any opinions?

I read an article about OCW after ladder testing at 7mm Rem Mag Load Dev Part 2: Audette's Ladder Test « Precision Rifles & Handloading It says to shoot 3 round groups of varying powder weights of .3gr increments using the promising ladder test nodes. I will be shooting these tests at 500yards, from a led sled, prone position.
From the ladder tests I have chosen 4 combinations of bullet and grain to OCW:
160gr Sierra SP, RE22, 61.9-63.4gr (12 bullets total)
168gr. Berger VLD Hunting, IMR4831 63.6-65.1gr (18 bullets total)
168gr. Berger VLD Hunting, RE22 63.6-65.1gr (18 bullets total)
175gr. Sierra SP, H4831, 61.9-63.4gr (18 bullets total)

I am running the OCW round of testing this weekend.

For those that wanted to know, here are the ladder test velocity graphs. I was seeking a fairly stable fps (2-4 shots) in conjuction with the promising nodes. The Sierra 160 gr. ladder test showed about a 10" dia. group for all rounds fired. Even though the Sierra 160 grain did not show a stable velocity group, I will be OCW tesing that bullet/powder using the higher, 61.9-63.4grain charges. It looks like a n accurate round based on the smaill "ladder" overall verticcal range. NOTE: the 168gr. Berger VLD Hunting, RE22 ladder test is to be done 1st thing this weekend. No data yet!

"They say that the best weapon is the one that you never have to fire. I respectfully disagree! I prefer... the weapon you only have to fire once." Tony Stark (a hunter?)

 

[jsthntn247]

Ladder test are mainly looking for results because of barrel harmonics and not fps. Don't get hung up because fps didn't plateau or even out over a 1.5 grain range. All fps evening out means is that you are reaching pressure limits or maximum fps for a given barrel length and powder combo.

 

[JeffP40]

Can you get good groups at any distance with the sled? I could be that the rifle doesn't like it. Have you tried it with just prone with a bi-pod, or off good bags on the bench? If it likes the sled, I would say stock fit.

 

[tstarky]

No I have not tried off the sled but will this Saturday. Just got 200 pieces of new Winchester brass, whahoo! Started preping them match style.

Ordered a new Stock, a Bell and Carlson Alaskan II Rifle Stock Remington 700 BDL Long Action Magnum Barrel Channel with Full Length Aluminum Bedding System Synthetic Bell Carlson Alaskan II Rifle Stock Remington 700 BDL Long Action Mag It should be here today. I should have her bedded by Friday in time for Saturdays shoot. Yes I love my rifle,.
Have a LR shooting clinic all day Saturday and more LR testing for this rifle Sunday. I should have more information after.
Here is some info from last Saturdays LR testing. A few ladders and some 3 round groups from promising powder/bullet combinations from the tests a few weeks ago.

 

[tstarky]

more info from 11/3/12

 

[tstarky]

Retumbo ladder and more 3 round tests

 

[Mikecr]

You're chasing your tail.
What's your round count so far?

 

[tstarky]

I prefer to think that I am doing a thourough analysis of three different bullets and three or four podwers in varios combinations.
I have shot about 200 rounds.