Ideal yardage for 308 ladder test?

[turbo54]

Tried searching, hopefully I'm not beating a dead horse.

As I understand it the idea of the ladder test is to show you what "zone" of charge weight gives the most flexibility in charge weights, by indicating bullets that left the muzzle while it was at the top or bottom of its whip.

Thus, you are looking for vertical dispersion based on muzzle velocity - which 100 yards won't readily show...but also grouping of somewhat dissimilar muzzle velocities (because barrel whip is more influential than a handful of FPS????). So, I would expect a ladder test at say, 600 yards to dull the obviousness of the "grouping" I'm looking for...?

I can perform the test at 200,300,400,500, or 600 yards. My club has pits, so I can even have my pit bitch pull my target and mark it after each shot.

So - what yard line ought I shoot from?

 

[jbailey]

Re: Ideal yardage for 308 ladder test?

500 or 600 yds.

 

[stonefly53]

Re: Ideal yardage for 308 ladder test?

Everything that a ladder test shows and the info you need out of it will be magnified at further distances. I just did my first string of ladder tests on a new 27" match barrel and couldn't hardly tell anything until i hit 600 yards and at 1000 it really opened up to find the groups.(maybe it was just my shooting that opened up) Anyway, shoot at the farthest distance available to make the test the most productive.

 

[turbo54]

Re: Ideal yardage for 308 ladder test?

Ok... good info. How big of a piece of paper you think I need? Shooting my standard load, I can usually shoot a 200-15X on an NRA high power 600 yard target.

 

[aquinas]

Re: Ideal yardage for 308 ladder test?

I usually use about 5 feet of 18 inch wide paper. I probably could get by with 3 feet, but on the light loads, I never seem to know where they will hit and they hit pretty low.

 

[stonefly53]

Re: Ideal yardage for 308 ladder test?

My 1000 yard target is 4' x 4'. I just use a white newspaper roll end and pin up a piece vertically on the target for the ladders.

 

[vman]

Re: Ideal yardage for 308 ladder test?

The further the better imo.

If wind is gnarly as, back it off, but if you feel comfortable and especially because you have pit crew... I would go to 600 as the results should really stand out more.

But 300 is generally the minimum.

 

[turbo54]

Re: Ideal yardage for 308 ladder test?

Thanks for the replys. Sounds like everyone is in agreement that further is better. I'll perform the testing at 600 yards.

Sounds like I have an almost ideal place to do my ladder testing:

A 600 yard range
A pit crew
A range that never needs more than 1 MOA of windage at 600 yards

Ok, I'll stop bragging!

 

[Trevor]

Re: Ideal yardage for 308 ladder test?

It a two parter.

the 1st, The further the distance the greater the discrepancy between incremental charges.

The 2nd is the ability to hold point of aim and the further out the distances the greater the impact on being able to hold the same aiming point. If you can’t hold the same point on the target the results are skewed

For myself 600 is practical max with a 42 powered scoped.

 

[turbo54]

Re: Ideal yardage for 308 ladder test?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Trevor</div><div class="ubbcode-body">It a two parter.

the 1st, The further the distance the greater the discrepancy between incremental charges.

The 2nd is the ability to hold point of aim and the further out the distances the greater the impact on being able to hold the same aiming point. If you can’t hold the same point on the target the results are skewed

For myself 600 is practical max with a 42 powered scoped.
</div></div>

Interesting... I have a 4.5-14 Leupold on my rifle, but I find with the fine duplex reticle, and I find that at 14 power at 600 yards, the black on the target is just big enough for me to cut into quarters with my reticle. I mentioned before that when I'm feeling good, and the gods favor me, I can usually fire a 200-15X string this way.

Sound good enough for this test, or should I move in closer?

 

[jbailey]

Re: Ideal yardage for 308 ladder test?

14x would be on the low end for the 600yd test; nevertheless, if you get a very visible point of aim it is doable. Get a big roll of white paper and do a very nice, plumb and square, POA target in a high contrast color to the white (black or blue). You aren't worried about windage, so only focus on getting clean vertically centered shots.

If you are doing this right, you will not need a partner to mark each shot - they will nicely fall in on their ladder rungs. You will see wide rungs for 75% of the shots and then hopefully nice tight rungs for the other 25%. Its those tight rung shots that you want to grab. When I did my ladder test for my 6.5x47 at 500 yds, I had 10 shots - with 2 or 3 inches between the low and middle end powder charges, climbing up and then literally 0.1" between the three top end shots. I did this test 3 times and the results were the same each time. Amazing how this stuff works.

 

[Leaddog]

Re: Ideal yardage for 308 ladder test?

Optics are an important consideration when selecting distance. If you are using high end optics with a fine reticle, you will be able to accurately control your shot placement at the longer distances. If not, stay in the 300-400 range. If your ladder test uses .5gr powder charge differences, the elevation will be plenty apparent at 300.

 

[vman]

Re: Ideal yardage for 308 ladder test?

If your already shooting 200-15X at 600 yards on a 20 shot string...

I say why would you look at lower really?

 

[turbo54]

Re: Ideal yardage for 308 ladder test?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vman</div><div class="ubbcode-body">If your already shooting 200-15X at 600 yards on a 20 shot string...

I say why would you look at lower really? </div></div>

Because the. 10 ring is 12"... I want to clean an F class target at 600.

 

[Trevor]

Re: Ideal yardage for 308 ladder test?

Sounds like you are shooting pretty well as it is. are the lost X's do to vertical or windage. If they are windage related i would leave your load alone as it seems to be working. If you are experiencing vertical problems than the test would be beneficial.

targets are another consideration for ladder tests as others have stated I would move away from the black target and go with a big white sheet and use aiming squares.. the smallest one you can clearly see at 600. squares come in many sized remember at 600 3" square is .5moa. Ideally you would like to be able to resolve a smaller square then 3" but i am not sure how clear your scope is... you would need to factor in the aiming square as pary of your vertical. At 300 yards when i test i use a push pin as the target at 600 i can get away with a .75" dot on a white sheet.

Here is a tip. adjust your scope so it hits high of the aiming point. there is nothing more frustrating then plotting shots and losing one because Dead i Dick had a perfect shot in the aiming square any you can't find the shot... been there done that.

As to your scope power i am not sure i have a 12x42 and only have it down to 20x to make sure i am on the page (right target) then back to full. if 14x works for you then why change... here is something to think about the cross hairs on a 14x cover much more target then scope powers of 42 50 or 60x. if you were to reference the top F class shooters in the world they all have higher powered scopes to minimize aiming errors. with only a 5" circle at 1000 it doesn't take much to be on the outside of the 10 ring to score a 9...higher powered scopes reduce aiming errors.

best of luck
Trevor

 

[turbo54]

Re: Ideal yardage for 308 ladder test?

Thanks for all the input! I would like a higher power scope and I may go that way. When I got started, (and got a good deal on this one) I told myself Simho used irons, and up until recently, the best snipers in the world used fixed 10x optics...so why should I need more? There is a direct tv satellite dish I dry fire at sometimes. Its right about 1500 yards, and I can resolve it on 10x. I've dry fired at it so much I WISH I could actually try the shot. Don't know if my 308 could get there (XBal thinks I can go 1475 with my 180smk@2525fps), but with the right dope, I think I could.

On 14x at 600 yards, I can nicely quarter-up a 3" spotter. I think that would work nicely for this test. I find that once I score a nice centered X, and the white spotter is nicely centered so it is a good aiming point , I tend to be able to shoot the spotted over and over. Trick is getting the first good hit!