Ladder Test, What's Next?

[B W E]

Ok, so I ran a ladder test on my new .308, and I honestly have no idea what to do with the results.

I know you look for 3 consecutive shots that are close vertically within the velocity perimeters you're looking for, but my shots don't really give me any insight.

This is from a R700 SPS Tac, Bipod, rear bag, 100 yards, 168gr. SMK with the following charges:

Varget
42
42.3
42.6
42.9
43.2
43.5
43.8
44.1
44.4
44.7

10 shots, 4 holes. The first 5 (42-43.2) are all in the larger hole at top, 43.5 by itself, then 43.8 and 44.1 touching, and at the bottom is 44.4 and 44.7 touching.

Only thing I can think of is do it again at 200 yards. Does that sound right??

[baih777]

were you checking the primers for signs of flattened primers or overpressure ?

[jtake]

You really cannot get good data from just 100y for a ladder test. Even 200y is a little short as the separation at that distance is not sufficient. Better off doing a OCW.

[Exodus343]

From my understanding from others with more experience a ladder is done at 300 yards or beyond

[B W E]

were you checking the primers for signs of flattened primers or overpressure ?

I checked each case and all looked good. No primer issues, no extracting issues, everything ran smoothly.

Here's how everything grouped. I only made 5 of each, so I used one of each for the ladder and then (10) 4-shot groups.

[BLR81]

I checked each case and all looked good. No primer issues, no extracting issues, everything ran smoothly.

Here's how everything grouped. I only made 5 of each, so I used one of each for the ladder and then (10) 4-shot groups.

Do you really believe that a change in powder weight from 44.4 grs to 44.7 grains produced a group size change form .604" to 1.485"?

That's the problem with the 100 yd OCW. A MOA rifle is going to produce good groups with multiple loads. Do you think manufacturers could sell pre-made hunting rounds if they didn't shot well in most guns.

At 100 yds, you'd probably need to shot at least 10 rounds of each load just to produce a large enough variance to see definitive differences in most groups. Bench rest shooters that lock their rifles into a fixture and only lightly touch the trigger might find it useful. But, your average R700 off a tripod is too dependent on the shooting skills of the tester.

If your not a top marksman, too many of the shots are going to be affected by you more then the load.

[krwada]

44.1 to 44.7

These charges are the sweet spot for your rifle.

Now ... you need to do the following:

1. Sort your brass and components
2. Re-test this region
3. Go to the range and shoot some more!

This is what you should do.

[B W E]

Thanks for the tips guys. I had a great time with this rifle, these are my first shots through it. Regarding the 44.4 & 44.7 POI changes, I truly think the charge had something to do with it. For me, the center of the target is the easiest to hold on because there is so much more orange there, it's much easier for me to hold my crosshairs steady and parallel / perpendiar to the lines. However , this is not so say there couldn't be some of "me" in that lousy group.

As far as components, all brass was once-fired Hornady Match, with CCI 200 primers, seating depth was 2.795" on all, and every charged was weighed individually. Only deviations that I know of are trim lengths. I use the cheapo lee trimmers, and I measure each case before I trim. If it's shorter than what the case will trim, I leave it alone. This allows for a +/- .005" or so on case lengths.

I did buy another 100 bullets, and my wife and daughter are going to Disneyland Sunday so...... More shooting

I'm thinking I'll choose the 5 best groups and load 10 of each and do (5) 10 shot groups. Is this an efficient approach?

[Brd_Hntr]

308_groupsize.JPG

If you think your shooting was solid enough to rely on the data. Shoot groups at and 0.1grain above and below the three low values (42, 43.2, and 44.4). If I got reproducible results I would pick the flattest valley (43.2) for further study and development.

[The problem around here, Nor Cal Bay Area, is all the local ranges are short (100 yards), so doing load development requires a long drive if you want to shoot more that a 100 yards.]

Side question: What bullet are you using?

[B W E]

Holy crap that's cool! What program is that? I'm shooting the 168 SMK. I think (I don't know what I don't know) I'd prefer to stay in the 44+ range for the sake of keeping velocity, but with a 20" barrel I can't really expect more than 800 yards or so.

[blaseoldber]

I checked each case and all looked good. No primer issues, no extracting issues, everything ran smoothly.

[baih777]

I made this so called target to help me build up my loads. its a lot easier to keep your crosshairs parallel.
99cent store poster board. they are two for 99cents and a thick felt marker.
I am still working on max loads for now. once I figure my max loads I will do a test more like yours to find that load that is consistant.

[Sir Toast]

I wouldn't do a ladder test under 500 yards. I know others that won't do it under 700 yards, even with a .308.

I'm building a target cam now to make it easy for a ladder test at long range. If it works and you're even in San Diego, shoot me a PM. (I won't be able to go out until fall though when it cools down. I'm broke right now and work is crazy.)

[3RDGEARGRNDRR]

Ok, so I ran a ladder test on my new .308, and I honestly have no idea what to do with the results.

I know you look for 3 consecutive shots that are close vertically within the velocity perimeters you're looking for, but my shots don't really give me any insight.

So where are the velocity results, a ladder test that close should really include chrono results if possible.
Remember to record the elevation and temps as well, a hot day can increase your velocity. If you started out in the morning and stopped by midday, your ammo could have heat soaked.
Log it all in a shooters log or DOPE log. and a picture of your target if possible.

When I ladder test for loads, i am usually 0.5-1 grain apart, then tighten up the load with a second outing where i am most accurate with a chrono data, at 100 yds. That is a lot of shooting in one outing, did you properly clean the barrel between strings or cool off the rifle? This can change your groups as well. If your groups are suddenly opened up, chrono data will tell you if your SD is off, thus, pointing to your handloading technique, which will require more work.
Oh, well, all of this is covered in your handbook, so check that out over and over again.

Then with your info, you will know where you should be dropping at further ranges knowing your velocties and BC when you go out again.
Handloading for a particular rifle can take a long time, especially when your components run out and you start all over.

[B W E]

Altitude was 1749
Bar. pressure was 29.884Hg
Temperature was 81.5 - 90
Humidity was 23%


My velocities were as follows:

This is one round of each charge weight: 168gr SMK
These 5 were shot on the lower of two target pages. This target page had me nearest the perfect elevation through the chrony
42.0 : 2527
42.3 : 2574
42.6 : 2597
42.9 : 2649
43.2 : 2713

These 5 were on the top target page, having me pass through the chrony only about 2" below the diffusers, so these numbers likely are off a bit.
43.5 : 2724
43.8 : 2678
44.1 : 2681
44.4 : 2740
44.7 : 2698

These were the velocities for my plinking ammo:

With these, I weighed the first, and just dropped the remaining 4 for each weight.

150gr. Hornady FMJBT
43.1 : 2661
43.4 : 2658
43.7 : 2677
44.0 : 2665
44.3 : 2673
44.6 : 2681
44.9 : 2791