ladder test question

[ReloadKy]

As I stated in one of my goals for 2023 I want to learn the 308 I have in the safe. So I picked up some new powders to try out. Accurate 4064,2495 and CFE 223. I want to try and do a ladder test. I have done them before using my chrono and going up in powder charge .2 grains for each load. My question comes from bullet choice. I have a box of 150 gr Nosler ballistic tips that I would like to load to hunt. I have a box of 150 gr Sierra game kings that I am kind of indifferent on. Can I use the 150 SGK to try and find the velocity node I want? I mean 150 grain bullet is a 150 grain bullet right??

 

[jimbires]

I'm going to say bullet profile will skew this .

 

[hunter24605]

I would think there may be quite a difference. Bearing surface length, engraving pressure etc will be different between the two creating distinct pressure profiles and different velocities. Maybe not enough to matter, I don’t know, but there will be a difference.

 

[TackDriver284]

Different brand of bullets have different shapes and ogives, lengths, etc. I would check the ogive for the bullets I would test to keep the distance to the lands at a minimum of .010" and work up loads. To work up a ladder, I would use .3 for small cartridges, .4 for medium sized and .5 for large. Once a node is verified, reduce to .2 grains to tweak and find optimal seating depth to finalize your load.
TBH, .2 grains to work up a ladder seems like a waste of powder and bullets.

 

[Charlie-NY]

Personally, I'd use the GameKings just to get your feet wet with the rifle. You'll certainly learn a few things as you work up a load and converting over to the Noslers, of the same weight, won't be a big deal. Minor tweaking of the load may be all that is needed for a hunting rifle. As usual when you change a bullet, you should reduce the load and work back up, but I'd expect the results to be very similar.

You could also use the Gamekings to foul the barrel after each time you clean the bore. I typically shoot 3 rounds on a freshly cleaned barrel before testing new loads.

 

[300WSM]

As I stated in one of my goals for 2023 I want to learn the 308 I have in the safe. So I picked up some new powders to try out. Accurate 4064,2495 and CFE 223. I want to try and do a ladder test. I have done them before using my chrono and going up in powder charge .2 grains for each load. My question comes from bullet choice. I have a box of 150 gr Nosler ballistic tips that I would like to load to hunt. I have a box of 150 gr Sierra game kings that I am kind of indifferent on. Can I use the 150 SGK to try and find the velocity node I want? I mean 150 grain bullet is a 150 grain bullet right??

No...
There are some that will say exactly what you're asking but in my experience the geometry of each bullet can differ the velocity and in sone cases significantly. In some cases 100 fps or more can be of difference. Charge for charge and bullet grain for grain but bullet "A" has more bearing surface (drag) within the bbl than bullet "B"...
(The part of the bullet that rides against the rifling.)
If you had blue prints of each you could possibly get close between two differing bullets if the dimensions were close but without that or an expensive comparator it's only guessing and assumptions.

Pressures are another issue and bullet "A" could be in the acceptable pressure range while bullet "b" might be too high ... yes even with equal charges.

My suggestion is this...
Armed with your chronograph load 5 rounds with your Ballistic tip's and 5 rounds with the Sierra's...
BUT...
Load both at minimum starting charge
Here you will be safe to compare and if the velocities are similar work up safely.
In other words the bearing surfaces are similar giving you very similar velocity results.
In this case yes you can use the one in place of the other.

If you find a big difference in velocity charge for charge then you can't just work up a load with the one assuming the other will work the same. It won't.

Good luck

 

[desertcj]

The node you find with one bullet won't necessarily be the same for the other. I'd generally say that you won't get into too much trouble though unless you're really pushing the max loads. FWIW, I use .5gr steps in 08 cases. That's about 1% of case capacity. In a .223, you're looking at .2 or .3 grain steps.

 

[RL338]

Short answer no. As other mentioned different material different profile won’t yield the same results.

 

[ReloadKy]

Thanks for all of the responses and information.