Ladder testing

[itchyTF]

I’ve been reloading for something like 47 years but only in the last year or so became aware of ladder testing. I lived in Vermont for a good chunk of my adult life and I think that’s where Creighton was from.

Anyway, I’m attempting to ladder my 6x47L and the following are the results so far.
The targets are at 400 yds. and the bullets are seated .010 in the lands. I’ve tried H4350, RL-17 and Ramshot Hunter so far with the 105 gr A-Max and 95gr Berger Hunting VLD. I’m trying to find the ‘right’ long range prairie dog load. Comments are welcome.

 

[Klong]

In the 105, I would try the 38.4 gr of H4350 for ten shots and look for any vertical.

 

[6BRinNZ]

Hi Guys,

just curious as to why you made the suggestions? ...i.e. what is it that you have looked for to make the recommendation?

 

[itchyTF]

Thanks for the replies. I was thinking of trying 38.3gr of H4350 for the 105 in a group. I'd still like to try N160 and N560 and maybe RL-19.

It may be my bench technique (or lack of it) but why do some of the ladders go up & down. RL-17 with the 105 on 9/6 is an example (up & down, up & down). Mirage was giving me some trouble on those days so that might be a contributing factor. RL-17 with the 95gr starts going up, peaks at 40.0gr then comes back down.

According to the Pressure Trace unit I have, the bullet is out of the barrel in less than 1.5 milliseconds. I'm not a physics guru but I find it hard to believe that inertia is overcome and the barrel starts oscillating or vibrating that quick.

I hope to hit the "range" tomorrow for more testing. None of the normal ranges around here go past 200yds. This "range" is a friend's private airstrip.

 

[Klong]

6BRinNZ, you look for a group of powder charges that group together. If you consider that as a round is fired the barrel reacts in a sine wave. The idea is to catch a barrel in a spot where the bullet exit is at the top or the bottom of the sine wave so that small changes in the load performance produce the least effect on the group when a group is fired

BTW, at 400 yards I ignore the horizontal and focus on the vertical dispersion.

 

[warbird]

im new but i thought your suposed to shoot at least 3 of each load [of one powder] and dont worry left and right so much its up and down is what your looking for, mabey i done it wrong? how do you tell without shooting more one shot per load?

 

[itchyTF]

Well, here are my results from last weekend. My M2 chrono was giving me some trouble during the N560 and RL-19 testing. I also have no idea what happened to the 41.5gr load of N560. I did not jerk it and it wasn't going fast enough to blow up. I'm puzzled.

I thought the N160 ladder was also strange. Very little vertical. It was breezy that day which may explain the horizontal in the last shot. The ladders were shot at 400 yds as before but the groups were at 300.

The Excel file has the loads, velocity and pressure data.

Looks like I'm going to have to post a few replies to get all the pictures in.........

Warbird - From what I've read there are some variations to the ladder method. Firing 3 shots instead of 1 is one of them.

 

[itchyTF]

More pictures........

 

[itchyTF]

Last one.