How to perform a ladder test?

[Texas10]

I've tried searching the archives for information on how to perform a ladder test when developing a new load, but can't seem to find anything. So….for the newbies (like me) here, I would like to start a conversation on this subject and ask you guys to please share your techniques. How to perform the test, starting in the load building phase, how to shoot, and what you're looking for when examining your targets and POI results.

As always, thank you all so much for your generous contributions, wisdom, and willingness to share your secrets. I'm sure we all appreciate it very much, I know I do and, thanks to you all, have come a long way in developing my skills since starting this hobby just a few months ago.:cool:

[Master Chief]

Google search "reload development ladder test" it will come up with a couple articles.

[D.ID]

Distance= longer is better 400 yards serves very well.
Ignore you windage (side to side) completely ignore it.
Vertical dispersion translates into velocity and barrel harmonic consistency.
Test only one component at a time or in other words start with x powder and y seating depth and do not vary it in the same test.
I add powder in 0.5 grain increments for large cartridges an 0.2-0.3 increments for smaller cartridges. Careful to keep them in the right order.
Shoot slow and deliberate all at the same point of aim carefully documenting each shot one at a time and when your done working up to max or pressure your shots will suffer from vertical stringing from velocity variations.
It's the spread of that vertical stringing that you can use to find nodes or groups of different charges that are the most consistent at producing comparable velocities.
They may go straight up or stagger based on either windage or harmonics and it is generally not reliable to assume which one.
They may climb then jump back down so it is important to follow along and not assume they are all climbing as the powder climbs.
You will see clusters of vertical and in order to stay away from the edge or border of those clusters you need to select your load from the core of those groups.
Use an oversized target to make sure you catch every round and do not attempt at 100 yards as the dispersion will not be pronounced enough to be definitive.

[LongRange]

Another thing that will help is to color the bullets after seated with different colored pins and shoot into white paper with a card board backer that way if you loose track you can see the colors...if you cant see any color around a hole just use a Q tip with rubbing alcohol and dab the hole to bring the color out.

[olddav]

What D.ID said with one exception, I have used the ladder test at 200 yards. I shot of sand bags both front and back.

[limige]

One thing I did was to use a camera tripod and rubber bands to video record the target from the side.
Get your shooting location all set. Rifle and ammo out then run downrange setup target and phone cam then go back lay down and prone shoot your ladder test. Aim at the same dot 400-500 or more yards start low and work to high.

Once finished get your phone and watvh the video.
As the bullets hit the paper number each hole 1,2,3,4,5,6 so on
Then make a corresponding chart with the lowest charge you loaded and the increments all numbered in order shot.
Look for vertical grouping. Do not pay any attention to horizontal at this point.

Shoot this test two or three times to confirm nodes. Then start your seating depth test. http://tapatalk.imageshack.com/v2/15/02/01/24d050efa8747dc14cc639d03ed406ba.jpg

[limige]

If you want better write ups checkout the reloading section on snipers hide and in the stickies are reloading for long range part 1,2,3,4,5
It covers ladder test as well.

Let us know how it goes.

My issue is I dont have enough distance to see the velocity spread. I only have 325 yrds. I would say you need a minimum of 400. Goal is you want to get out the grouping realm and into velocity and harmonics

[Texas10]

Thank you so much guys! That's quite a lot to chew on….I'll check out the various websites mentioned for more information.

Limige, I do frequent the snipers hide website but never saw that thread, so thanks for the heads up!

Master chef, I performed a search as you suggested and it yielded enough material to keep me reading well into retirement :)

Good tip about using markers, Longrange. When I get out so far I can't see impacts, that will definitely help.

D.Id, I'll probably have to get back to you on interpretation. I know I have a harmonics issue, but it may be at least partially in the fit of the stock to action.

My local range does offer targets out to 300 yds however, at this time of year they are covered in deep shadow due to the low sun angle and nearby trees. But as oldav suggests, 200 yds is workable, and I can see the impacts through my scope so I won't have to risk a camera.

Then there's the issue with my cheap scope that does not return to zero. Can't say I wasn't warned :(

In the mean time, I have loaded 5 rounds each of 4 to 5 different velocity loads using two powders I want to compare, to see how they group at 100 yds.

Should be interesting..

Baby steps……baby steps.

[earl39]

Then there's the issue with my cheap scope that does not return to zero. Can't say I wasn't warned.

Scope doesn't need to return to zero because once you get on target you never change scope settings. All loads are shot without making any adjustments to the scope.

[limige]

Yep just make sure your starting load is hitting paper and go. They will keep rising.

I shot this ladder with my 22-250 last year at 325 yrds.

I did not find it very useful
http://tapatalk.imageshack.com/v2/15/02/02/d68ff8af8f00fc61dfd3f6c82c354127.jpghttp://tapatalk.imageshack.com/v2/15/02/02/f8e0a1281bf0a717a1ec836c76c5d25e.jpg

[JTCrl]

Ladders can be shot at any range, even 100. It's just easier to interpret them at longer ranges since the "string" is longer. Wind also becomes more of a factor at longer ranges and yes, crosswinds do induce a vertical component. If practical you might consider shooting your ladders at the range you do most of your regular shooting at.

Another tip is to shoot each load at it's own target. Even with a good spotting scope I find it hard to see .22 holes at 300 yards.:chargrined

As mentioned above you need to repeat the test at least a second time to verify your results. As an example I shot a 300 yard ladder test with a 223 shooting Berger 55s with H4895. Charges from 23.8gn to 26gn in .2gn increments. Total vertical component was 6 inches. Given that this rifle at best will shoot 1" groups at 300 yards there's no way to know what is a node and what is just the result of normal dispersion creating what looks like a "group". Plotting 2 or 3 ladders with the same loads makes it a lot clearer. I always shoot ladders over a chronograph and plot the velocities where nodes can also be identified. When a node on your ladder plot and a node on your velocity plot match up you've found something to work with. l have tried shooting 3 consecutive ladders, I have also tried shooting groups of 3. I haven't found an advantage either way.

:

[limige]

Short range ladders are fairly useless you might as well do an OCW test.
Long range ladders show you velocity AND barrel harmonics. For best results shoot two or three or them. Yes wind can induce vertical so its best to be 90 degrees or full value when shooting to reduce the affect.

If your gun shoots a 2" group with a given load and all your ladder test falls in a 3" group how much can you really make of it.

Stick to ocw for short range. Your doing the same thing different method

[Texas10]

What is an OCW test?

[limige]

lol, well now you can really pull your hair out. of course you can google it and find the article..

basics are load three to five of each powder increment. I find .3 gr steps reasonable. minimum charge to 2 gr over high.

set out a target or target dot for each powder charge at 100 yrds.

start low and work to high shooting one bullet at its corresponding target (keeping each charge on its own target) only shoot one of each charge. allow at least 2 minutes to cool bolt open between shots. stop if you see pressure signs such as hard bolt lift or flattened primers and note your max charge... stay .5gr or more below this charge in the future

now start over working from low to high one shot on each target until you have shot all your safe charges. don't be scared to use large black marker to note what target belongs to what charge in case you get on the wrong target

now once finished you have to decipher. it helps to post pics of results and ask for help from veterans. believe me its tricky

you will notice scatter nodes where you have a decent group going and the next one flakes out. this is due to barrel harmonics

your not looking for the best group your looking for common center points of impact

imagine this, connect all three bullet hit and find the center of the triangle, do this for each target. your looking for the zone where 4-5 targets all hit about the same vertical point.
seating depth will bring the groups in. you can tune almost any powder charge with the needed seating depth but your best groups will be when the barrel pauses from its high or low point.

this is why the 500 yrd ladder is so much easier to read. but if you only have short range do it ocw style. you may want to shoot it at 200 yrds to make it easier to decipher

[limige]

heres the write up

http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134