Ladder test and OCW

[Exodus]

Since I am very near doing load testing for my 308 I was brushing up on how it is recommended to do the ladder test. While searching for this I came across the OCW test. OCW Overview - Dan Newberry's OCW Load Development System

My plans for the ladder test were to run 3 strings which would eliminate what the guy that developed the OCW test says the faults of the ladder test are. I do like how you can get pretty reliable results at 100 yrds going the OCW way as the ladder gets to be a jumble at 100. Think I'm going to go the OCW route as in using a seperate target area for each load. Beats having to color the bullets so I know which is which.

 

[Kirkd]

Im new to reloading for long range shooting myself. From my research, you need to shoot a ladder test at 300 yards minimum. The longer the distance, the better. The OCW is shot at 100 yards. I will probably end up doing the OCW because zi have access to a 100 yards range. I still want to shoot a ladder test as well.

i have lnked a video sbout the OCW that is pretty good. He even talks about the pitfalls of a ladder test (manly the time to do it).

Mail Call Mondays Season 2 #35 - Optimal Charge Weight (OCW) and Optimal Barrel Time (OBT) - YouTube

 

[Broom_jm]

What I like about the OCW method, versus the ladder test, is that it gives you a charge weight that is not as sensitive as some loads can be. For example, my son's H4895/155gr A-Max load is VERY touchy about the measured charge weight. The load I use for my 270 (H4831SC and 140gr AB) can be off half a grain either way and the groups won't open up. My son's 308 is a target rifle while my 270 is used for hunting. I think the OCW method is much better if you're working up hunting loads. I also think OCW loads are more suitable for loads that will be put together with brass of various head stamps. The internal volume of the cases doesn't matter as much because the load itself is not as sensitive. This makes it ideal for working up plinking loads, IMHO.

 

[kludge]

Both methods have their strengths. At a short distance of 100 yards the OCW method is perhaps quicker/easier to read, and can answer the "dwell time" question (aka optimal barrel time) just as well as the ladder method, but the OCW method does not answer the question of SD and ES as well as the ladder method. Ultimately ES will determine vertical spread at long distances which doesn't necessarily show up at 100 yards. The ladder method - if you have the range - can answer both questions equally well.

Or if you have a chronograph, the OCW can work just as well if you take the time to look at SD and ES numbers to avoid a load that shoots at 100 yards but avoids the "where did all this vertical stringing come from?" at long range that sends you down the path of glass bedding your action without any positive results. But there goes the time advantage of the OCW method.

If you have the range and lack the chronograph, then do the ladder method.

 

[Broom_jm]

I guess I shouldn't automatically presume that folks will be using a chronograph when testing accuracy loads...there are times when I don't. However, I would add that every load I have worked up that fell in the sweet spot, using the OCW method, has also shown to have low standard deviation (SD) and extreme spread (ES) numbers. If the ultimate purpose of the load is to shoot/compete at 300 yards or greater, there is simply nothing else for it but to actually shoot those distances, to know how your bullet is going to perform. From that perspective, a ladder test at 300 yards makes a ton of sense.

For hunters, the OCW has definite advantages, IMHO.

 

[kludge]

True.

Put another way, groups don't ever get better at longer range.

 

[Exodus]

I do have a membership to a 100 yrd range and have a chrony. Supposedly have access to a 900 yrd range also but thats yet to be seen.

 

[Broom_jm]

Something between those two extremes would be nice.

 

[Exodus]

900 is just the farthest it goes. It supposedly has steel setup all along the range.

 

[Kirkd]

What would be the point of doing a ladder test of you don't have a chrony or acess to one? You need to know your velocities for the ballistics!

 

[Exodus]

Any of the tests would essentially be useless without one.

 

[Broom_jm]

What would be the point of doing a ladder test of you don't have a chrony or acess to one? You need to know your velocities for the ballistics!

Well, if the OP can actually shoot at all ranges, from 100 to 900, he will have the ability to confirm "paper" ballistics with real-world results. Guys were shooting pretty amazing groups at 1,000 yards long before most had access to a chronograph. Also, if your load data says you should get "X" velocity, with "Y" drop at 300 yards, when zeroed at 100, it's easy enough to confirm all of that by actually shooting those distances.

Perhaps more to the point, whether in competition or in hunting, using a chronograph to know your velocity and printing off a drop chart will never replace the need to go out and SHOOT at those distances. And I don't care what the various scope makers and their adjustable turrets would like us to believe.

 

[shawnba67]

What would be the point of doing a ladder test of you don't have a chrony or acess to one? You need to know your velocities for the ballistics!

Calculated ballistics dont always agree with real world on target basllistics, you can calculate all day.

But you cant argue with the target.

 

[Broom_jm]

...But you cant argue with the target.

And believe me, I've tried! Especially when that 5th shot is telling me I ruined another beautiful group!

 

[sloughfoot]

Wind is the greatest ruiner of a good group. Faster is better for bullets at 300 yards or greater. You can see it in the spotting scope if you are a good spotter for your buddy. If his bullet is arcing high then down into the target because of too low velocity, you can predict where the wind change will throw it out.

I tried the ladder test stuff and discarded the concept. I go for maximum velocity for caliber for best results. Overall best results.

JMO.

 

[Sniper 79]

Nice post! "Real Word" is the only way to go. I dont own a chrony and dont see the need for one. Shoot a mono reticle scope and leaned my holds. Less is more in my opinion. Tune your loads to your gun shoot away and be happy. Life is good.

 

[Broom_jm]

Yep, less lines in my scope, less twists of a turret, less relying on drop charts, and more shooting at known, realistic distances. That's the only way to get good, regardless of the technology used.

 

[Exodus]

Well spent all last night and the morning loading up some for doing the OCW test. Got to the range 26 degrees and all. Got the optic all lined up and bore sighted. I loaded two sets of the test with two different brass headstamps. I had two a lower than my lowest test rounds. Put the lowest one in and fired. (Started off at 50 yrds then was going to move out to 100 once I had it close) It hit windage perfect and elevation was high. Adjusted for what I though would put me dead on and put the next round in that was loaded a little hotter but still lower than my test loads. Fired and it hit almost as far down as it hit high on the previous round. (I still need to figure out these mrads) This however was as far as I got. The brass was stuck in the chamber. Guess what I didn't bring to the range.

So I drive the 20 miles back home and lightly tap the brass out with a cleaning rod. I don't see any signs of overpressure that I can tell possibly extractor kiss or whatever it's called. Primer looks fine. So I try and chamber another round and I can't even get the bolt closed. Tap that one out and look everything over. Try another and it goes in and out fine. So I try the rest of what I had loaded out of that bunch and they all cycled fine.

This was with TZ brass. When I was loading it up I could noticeably see that the internal volume of the TZ brass vs the winchester brass was less.

What should I do? The TZ brass I have loaded is all even hotter than the two I had shot. Crappy thing is I got a boat load of the TZ brass and very very little of anything else. Planning on going back to the range tomorrow and testing the winchester headstamp loads.

Guess I need to just bite the bullet and buy some new brass.

 

[Broom_jm]

Is this with a bolt action or semi-auto? What are you exact load details?

 

[Exodus]

I'll edit this post when I get to a computer. Bolt gun 308. IMR 4064 180 gr SBT. the first shot was 41.5 gr all seated at 2.800 second was 42 gr. Max listed on hodgdon website and my sierra manual both are 45.2 gr.

Edit: Ok just got back fromt he range. Ran the Winchester brass fine. Signs of overpressure (small kiss) at 44.7 gr. So I tried one of the TZ again it was loaded at 42.3 gr and had to tap it out. There is no kiss mark like the win brass was getting on this one.

Velocity on the win brass loaded from 42.3 to 44.7 went from mid 2400s to mid 2600s (IIRC). The one TZ loaded at 42.3 was mid 2500 (IIRC). I'll change/update when I get everything unpacked, eat, and deal with the wife.