Ladder test on new barrel.

[rhovee]

I am going to be getting a new barrel installed in a few months. It's an overbore cartridge so i am wanting to try and do load development effeciently. I know that barrels speed up between 80-100 rounds and this can throw development off. If you shoot a ladder with a fresh barrel and find an accuracy node, will it remain after barrel is broke in as long as pressure isn't reached?

 

[Willie]

You might get close, but will probably need to tweak it a bit. I prefer to fire form and sort 100+ pieces of brass. I do this while doing barrel break-in, pressure testing, preliminary seating depth testing and comparison of powders & primers.

By then, the barrel has settled, my brass is ready and I feel more confident shooting my ladder.

Oh Yes, it takes my mind off using up a hundred rounds of barrel life.

 

[Keith Glasscock]

Just tried it - in a word, maybe.

New 284 barrel (70 rounds fired) showed a 600 yard ladder node at 0.4 grains wide. Shooting the lowest end of the ladder node results results showed excessive ES (45+ fps). Associated vertical with the ES was present. I never tried the middle of the ladder node knowing that the barrel would speed up.

80 rounds later, the node is 0.5 grains less, the velocity is up 50 fps, a reduced ES (10-15) and groupings consistent with being solidly in the node.

Interestingly, the velocity of the center of the node was the same at both times, so tracking velocity would make it possible to adjust when needed.

Note that this barrel took 150 rounds to speed up and stabilize. The last 20-30 fps happened almost like flipping a switch. If you are close to the pressure limit, you could find it over pretty quickly.

So, I think it could be doable under limited circumstances. I just shoot the suspected final load (lower) for local matches or practice until a barrel speeds up.

 

[Scott Harris]

Just tried it - in a word, maybe.

...

Interestingly, the velocity of the center of the node was the same at both times, so tracking velocity would make it possible to adjust when needed.

....

When a great-shooting node has been found (via ladder testing), I record the velocity range and try to maintain this speed as things change. Velocity drops off over the life of the barrel....add more powder to bring it up to the original velocity. Powder lot changes...tune to the original velocity. Barrel speeds up after break in.....tune to the original velocity. For me, this greatly reduces the load development process: one ladder when the barrel is brand new to find the best velocity, then keep it there over time. I hate load development and the barrel life it consumes, so this is my caveman method. I "think" it works, but what do any of us really "know" in this business.

For what it's worth, I think a ladder test is, by far, the most effective way to find a good load. The results stand out clearly at 600 yards and further. Most of the time, my new barrels tune exactly where the old barrels did.

 

[rhovee]

I’ll have to keep good records on what’s shooting best and try to maintain that with the barrel. It’s a rebarrel on the same cartridge but 1” less length.