Almost a ladder test, but a unique way to load dev

[Tomcat]

What do you think about this approach to developing a load:

I load Federal 175 MK, with Varget, Federal brass, Federal 210M primers.

I started at 41 grains and increased the charge by .1 grain all the way to 46.6

I used (on the average) 10 shot groups. (yes, this took a while).

I graphed the results of average speed and found that velocity rises as the charge increased (no surprise there), up to a point.

At above 45.5 grains, the velocity increases were no longer stable, there are variations in velocity. The graph went mostly horizontal on the velocity x-axis. The more charge did not come with a velocity increase, thin ice there.

I kept my load at 45.3 grains Varget, which for me yields a node at 2720 FPS with good accuracy in my GAP Crusader.

Elevation is 10.5 at 500, and 33.25 at 1000 yds.

Opinions?

The primer are pretty flat, but with no stamping signs on the brass face.
I havent blown a primer yet, and during reloading, the pockets feel pretty tight - even using Federal brass.

 

[SVG308]

Re: Almost a ladder test, but a unique way to load dev

While not a very efficient way to develop a load, the important thing is that you found a load. I don't think going in .1g is needed in initial stages, only once fine tuning a node. Regardless, if it works for you that's all that matters!

 

[MALLARD]

Re: Almost a ladder test, but a unique way to load dev

can we see your graphed results ?

 

[crewchef]

Re: Almost a ladder test, but a unique way to load dev

Using exact same components I started seeing heavy bolt lift and ejector marks at 44.4. This was in my Remington SPS with 20" factory barrel. The best accuracy node was 43.4 and it's running average of 2610 MV. When I was working up the load I did go ahead and shoot 44.7 and 45.0 but after seeing the 3 cases I shot w/ 45.0 of Varget I didn't even fire the 45.3 and 45.6 loads that I had. I was seating pretty long which might make a difference but seems that would provide extra capacity in case and keep pressure down?

 

[wfjames22]

Re: Almost a ladder test, but a unique way to load dev

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tomcat</div><div class="ubbcode-body">I started at 41 grains and increased the charge by .1 grain all the way to 46.6

I used (on the average) 10 shot groups. (yes, this took a while).</div></div>

By my math, I figure that you shot 570rds in load development. Is this correct?

 

[crewchef]

Re: Almost a ladder test, but a unique way to load dev

Your load info was bugging me so went back and looked at my notes and also Hodgdon web site. Just for reference here's their data for 175 SMK with Varget, this is using Winchester brass which has larger capacity than the Federal.

175 GR. SIE HPBT Hodgdon Varget .308" 2.800" 42.0 2583 42,600 CUP 45.0C 2690 48,600 CUP

 

[Dog Doc]

Re: Almost a ladder test, but a unique way to load dev

What barrel length is your GAP?

 

[Top Cat]

Re: Almost a ladder test, but a unique way to load dev

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tomcat</div><div class="ubbcode-body">I started at 41 grains and increased the charge by .1 grain all the way to 46.6

I used (on the average) 10 shot groups. (yes, this took a while).</div></div>

So are you saying that you fired nearly 600 rds testing one load?

If I read that correctly...man, that's a lot of work.

The ladder test was designed to find a good load quickly and avoid all that barrel wear.

OBT testing tries to minimize load testing even more.

I like to try to find a good shooting load in one range session, and within one box of ammo.

You would have a lot of data points though, and you might publish your results.

TC

 

[Bill Larson]

Re: Almost a ladder test, but a unique way to load dev

Opinion..... not a cost effective/time effective/barrel wear effective....method of load development.
Save time/$$$/barrel life....Use proven existing methods...there are a few....
bill larson

 

[armorpl8chikn]

Re: Almost a ladder test, but a unique way to load dev

So you fired over 500 rounds testing one powder and one bullet, essentially to find one load?
You asked as your heading, "What do you think about this approach to developing a load."
Were I to answer that honestly I would likely be banned and/or hurt your feelings, piss you off, etc. So in the interest of brevity and forum rules I will simply say your method is extremely ineficient and unnecessary.

 

[TexIndian]

Re: Almost a ladder test, but a unique way to load dev

I have been known to graph my powder vs velocity before just as an exercise to see what I might learn about the efficiencies of a particular powder. Too much time on my hands, I guess. But I never used the graphs to find a load.

 

[Fuzzball]

Re: Almost a ladder test, but a unique way to load dev

"What do you think about this approach to developing a load:"

I think you better not hope to try several bullets and powders. Or do much experimentation in seating depth. ??

 

[pjparker]

Re: Almost a ladder test, but a unique way to load dev

Your results seem to confirm what I have heard and experienced in the past. As powder charges approach maximum, each incremental increase in charge weight results in a smaller increase in velocity. It pays to pay attention to what your chronograph is telling you.

Paul

 

[darkgun82]

Re: Almost a ladder test, but a unique way to load dev

Seriously....no way I'd spend that much time or money figuring one single load.

 

[flashhole]

Re: Almost a ladder test, but a unique way to load dev

If you did shoot all those rounds to get one load I'd have to agree it's not too efficient. I've done about two dozen ladder tests and one common thread I found after the first dozen or so was I never ended up with a load near the bottom of the load range. Now I start in the middle of the load range and work up in smaller increments. Saves components and gets good results.