New Ladder test

[esshup]

I can understand how the seating depth will change the node for standard throats, but how does one play with the seating depth with a Weatherby chamber? If it will have an effect on the node, how many thou should the depth be changed? Or is this dependant on the dia of the bullet (i.e. .257 dia vs. .460 dia)? In a standard chamber what is the rule of thumb for coarse seating depth adjustment? Reason for asking is that I have 2 Wby's and one non-Wby that I will be fine tuning in the upcoming weeks.

 

[Lightvarmint]

This idea is cogent. We should do what works. For me, if I begin with the bullet seated at the lands, my pressures are usually at their highest, as they should be. This leaves me with one direction to tune, and that is to seat deeper, where consequently, the pressures tend to drop. If in fact I can get a better load with a bullet seated deeper and pressure drops, I can always add more powder to see if the load can be tuned even more.

My problem is I tend to get lazy once my loads are in the .4 range and under at 100 yards.

Derek,

You are spot-on. It is MUCH easier to eliminate variables when you have to only work in one direction. Our method is very similar to yours except that we start with the bullet at .030" off the lands. We have NEVER failed to find a load that would tune to allow the shooter (in good conditions with a good trigger, scope and bech equipment) to shoot in the zeros and have minimal spread on velocity.

We actually thought that we were going to have to eat some crow with our procedure a few weeks back as one of the guns would not break the .5 MOA barrier consistently and we had stated on numerous occassions that they all will shoot in the zeros and boy were we worried...... However, we maintained our standards of (less than .1 MOA at 100 yards) and slowly eliminated the variables and ultimately found a faulty Jewell trigger and a faulty Nightforce scope. With those two variables eliminated (scope replaced and trigger swapped out (note to Kirby: we just pulled out the trigger hanger vice taking the gun out of the stock), the gun started "showing out" as it was designed to do.

Keep up the good work and don't sacrifice high standards when it gets difficult..... The other thing is that when the groups are big, the bullets may not be "asleep" yet.

James

 

[Forester]

I would load some groups in the 36.2-.4 area and also try the 36.8-37 area. Without Chrono data you are really playing with less than half a deck in my experience. It seems to me I could almost shoot a ladder through a chrono and not even at a target and get the best results by looking for nodes in the velocities.

 

[Lightvarmint]

Hello again,

If you guys are loading them in tenth-grain increments, then with a powder scale that is only accurate to .1 grains could yield + or - .09 grains and you would think you are on the money for the powder charge.

For instance the 36.2 targeted powder charge could come in at 36.11 to 36.29. Then the 36.3 targeted charge would come in at 36.21 to 36.39. The scale error is overlapping the intended powder charges and you are probably testing the same powder charges for the two different recipes when you are not intending to do so.

James

 

[tx_shooter]

Hello again,

If you guys are loading them in tenth-grain increments, then with a powder scale that is only accurate to .1 grains could yield + or - .09 grains and you would think you are on the money for the powder charge.

For instance the 36.2 targeted powder charge could come in at 36.11 to 36.29. Then the 36.3 targeted charge would come in at 36.21 to 36.39. The scale error is overlapping the intended powder charges and you are probably testing the same powder charges for the two different recipes when you are not intending to do so.

James

I understand what your saying/ getting at. I'll be as precise as I can be until I get a more precise scale. I figure if I load each round the same way each time with the same equipment; then that's the best I can do at this time. Just wait till I get a more precise scale.

 

[Lightvarmint]

Hello,

Until you can get a different scale, you might want to try tuning with seating depth and use the blink method from above on the powder charges.

James