What's Your Favorite Load Development Methodology?

[Chrazy-Chris]

I am just getting into 6.5 Grendel reloading and I plan on sticking with 123SST's since I want to have the ability to hunt with it without the hassle of working up a separate hunting load. I have two powders to try - Tac and 8208XBR. I know I won't be happy unless I'm reaching the velocity potential of my barrel (20") so I'll probably start about halfway between min and max and then work up .5gr at a time for each powder to .5gr above max (unless max is a compressed load). I'll load 4 of each weight (5 just seems like too many but three doesn't allow much shooter error). I then proceed to shoot each group, running a bore snake after each four round group and allowing the barrel to cool. I may start with a group of factory ammo for a baseline and to warm/foul the barrel. At the end of the day I hope to be able to see the nodes and then pick the right load for my gun. I then write it down in 10 different places so I don't lose it, take photographic evidence, chrono it, hahaha you get the story.

What's your guys's load development methodology?

[LRRPF52]

I'm glad you brought this up and shared what you are planning.

A general rule I adhere to for determining load increments is 1% of usable case capacity with the particular powder.

Example: Max load with IMR 8208 XBR under a 123gr is 28.5gr. 1% of that is .3gr. Using .5gr increments won't give you enough resolution as to what's happening, and can blow into spiked pressure territory, which your 29.0gr load of 8208 would do. 8208 XBR is fast for a 123gr, but as long as you limit yourself to 28.5gr or slightly less depending on the chamber and COL, you'll be at or under 50,000psi. Once you go to 29.0gr, it will spike on you bigtime.

Do use the start loads so you can build a pressure/velocity ladder. You don't have to load 3 or 5 cartridges with each increment, just load a ladder with single loads going up incrementally.

The pressure ladder will tell you where your trend is, in other words, how many fps average you are getting with each increment of charge weight.

We have generally seen that .3gr with most powders in 6.5 Grendel gives you about 17-25fps with cup and core bullets. You may see one or two larger jumps than that in a ladder in the 30-45fps range, and some that don't increase at all, but you will generally see the 17-25fps between the others. That's a good step range to work with for load development. You will see nodes with that when chronographed.

You can do 3 ladders like this to eliminate incidentals/outliers when developing the trend line.

[Rickc]

My loads development changes with what use the rifle is intended for.

I agree that with the grendel case volume your ladder should be 0.3 grains increasing

I really like this one for finding a wide node for easy reloading of hunting ammo.

Pick your powders. Pick your starting load. Load 3 of each powder charge. Take a magic.marker and color each different powder charge group a different color. Color from tip to ogive. Get a large sheet of white paper put an aiming point in the middle and post it on your range at least 300 yrd. Further is better. Shoot your rounds round Robin. In other words shoot one of each powder charge and then go to the second of each and then the third.

What you are looking for are 2 or more powder charges that have close to the same POI. That is the node you want to work with. That node will not require as precise powder charge either. The color.will rub off on the white paper. Just push the hole.closed from the back and you will see it.

This method also keeps you from trying to shoot those tiny groups that we often screw up.

Oh and horizontal doesn't really matter. Only vertical.

[lrgrendel]

My loads development changes with what use the rifle is intended for.

I agree that with the grendel case volume your ladder should be 0.3 grains increasing

I really like this one for finding a wide node for easy reloading of hunting ammo.

Pick your powders. Pick your starting load. Load 3 of each powder charge. Take a magic.marker and color each different powder charge group a different color. Color from tip to ogive. Get a large sheet of white paper put an aiming point in the middle and post it on your range at least 300 yrd. Further is better. Shoot your rounds round Robin. In other words shoot one of each powder charge and then go to the second of each and then the third.

What you are looking for are 2 or more powder charges that have close to the same POI. That is the node you want to work with. That node will not require as precise powder charge either. The color.will rub off on the white paper. Just push the hole.closed from the back and you will see it.

This method also keeps you from trying to shoot those tiny groups that we often screw up.

Oh and horizontal doesn't really matter. Only vertical.

Rickc

Great explanation.
I could never get the coloring of the bullets to work so I do it slightly different with the same results.

Let's say you have 7 different powder charges. Use 7 different identical targets and trace the results on to a piece of cooking paper or parchment with a pencil. You will then have all the results on a single piece of paper to decipher your results.

Just an idea........

[sneaky one]

Any paper. Then capture your target sheet for a transfer. I've loaded for the Grrr for 9 years now-- almost all loads were best accuracy about .3 grns. less than max.

That's the beauty of this round--- consistency.

I did my workups by, .1 & .2's.


When I was very close to perfect with my Gmx loads--- I switched to carats- to fine tune it. Painstakingly, with a tweezer------


I don't recommend it, unless you've been at this a while. Kidz!!!! Don't try this at home! A simple tragic mistake could happen.

Stick to grains as a measurement tool. Get a very good quality scale.

[Chrazy-Chris]

Thanks all for the great advice and explanations. .3gr increments it is.

Sneaky one - which scale do you recommend? I've been using the Frankford arsenal mini digital scale, calibrating it before every use and checking it for consistency throughout (my pan weighs 68.4gr so it shows -68.4 when removed). Is this a good enough setup for my use? I've been doing this for years with other rifle calibers. I reload mostly for cost savings so any reloading equipment purchases are strictly made.

[Chrazy-Chris]

Here's another question that I was expecting to find in this forum but didn't see - what OAL do you start with? For my 77gr long range .223 loads I try and load them as long as the magazine will reliably take, so I was planning on doing the same with the Grendel as long as this doesn't mash the bullet against the rifling. Again, I'm using 123SST's. I don't mind the cannelure being exposed and unused if it helps with accuracy to have them loaded a bit longer. I'm using AR stoner mags and it seems like there is plenty of room to go longer.

[1911man]

My favorite load is 28.3 grains of AR comp with a 123 AMAX (now ElD), CCI 450 and 2.260 OAL. AR comp has become my favorite powder after playing with TAC, XBR, and CFE. That load averages 2500 fps in my 18 BHW barrel and 3/4 MOA accuracy out to 600 yards so far. This powder is also very temp stable in my experience. With TAC I found 28.5 grains and a 120 SMK to be very accurate but velocity was alot lower around 2400 fps. With XBR 28.3 grains and a 123 AMAX was 3/4 MOA accurate but slower than AR Comp at around 2450 fps.

[65Whelen]

My local range only has 200yds max. Will the ladder method work at 200? I normally shoot for groups. On the bad side it can be a tedious, on the other side it's a lot of trigger time.
My method:
Pick a bullet
Pick a powder
Determine loads at .3 increments
5 loads
5 shots per/load @ 100yds

[kymountainman]

I've been ladder testing various loads since the mid 90s, and have always done it one way.


Start at minimum and load increments of .5 grains. Whichever load is closest to most accurate .... load more -.3 and +.3 from there. Then mess with seating depth if you are looking for tighter groups than that.

Of course ... 90% of the time I am dealing with bolt rifles. For semi auto I usually start at a known accurate load and tweak it from there.

Edit ... I forgot to add ... I sometime load as much as .5 grains over max, depending on the powder. Also, I'm always inspecting each case for low pressure signs, high pressure signs, and proper case to chamber seal. If you get a lot of excessively dirty cases ... this is a sign of incomplete propellant burn and case seal, and the extra gas is making it past the case / throat seal back into the chamber.

[Chrazy-Chris]

My favorite load is 28.3 grains of AR comp with a 123 AMAX (now ElD), CCI 450 and 2.260 OAL. AR comp has become my favorite powder after playing with TAC, XBR, and CFE. That load averages 2500 fps in my 18 BHW barrel and 3/4 MOA accuracy out to 600 yards so far. This powder is also very temp stable in my experience. With TAC I found 28.5 grains and a 120 SMK to be very accurate but velocity was alot lower around 2400 fps. With XBR 28.3 grains and a 123 AMAX was 3/4 MOA accurate but slower than AR Comp at around 2450 fps.

That's awesome! I have 2lbs of AR-Comp that I was planning on using for .223 but I'll definitely have to set it aside for the Grendel. Which reloading manual has data for AR Comp with 123gr in the Grendel? I don't recall seeing it in any of the books I reviewed. Or is it a pet load? Also, what's your COAL with the 28.3gr of AR Comp and the 123 Amax? I assume this is a compressed load - do you find that it's a pretty tight fit? I'm kind of new to compressed loads and there's something about literally compressing the bullet on top of the powder that still gives me the heeby jeebies.

[diddlyv]

In my high power days I would start with a mid range load. Go up in .5 grain increments if there was room for 5 or 6 to hit max, if not start low enough off of max to get 5 or 6 loads. This was with a 7.62 nato. Shoot 5 round groups looking for the best group. Then go up or down in .2 grain increments looking for a more accurate load in between the .5 grains. Was not smart enough back in the day to round robin or look for a tendency to group in one spot. Still not completely sold of the round robin but... For the small case capacity of the grendel I would use .2 or .3 grains as my increase then .1 more or less increments to see if there was a better load than the .2 or .3. Now have a Lab Radar and can get velocities, something I lacked in HP days. Luckily a shooting buddy had an oehler 35

[1911man]

That's awesome! I have 2lbs of AR-Comp that I was planning on using for .223 but I'll definitely have to set it aside for the Grendel. Which reloading manual has data for AR Comp with 123gr in the Grendel? I don't recall seeing it in any of the books I reviewed. Or is it a pet load? Also, what's your COAL with the 28.3gr of AR Comp and the 123 Amax? I assume this is a compressed load - do you find that it's a pretty tight fit? I'm kind of new to compressed loads and there's something about literally compressing the bullet on top of the powder that still gives me the heeby jeebies.

My COAL is 2.260 and yes this is a slightly compressed load for me. If you run a shorter OAL your going to hear alot of powder crunching. Its important to note that this may be above the max for your rifle. In my experience the Poly rifling in my BHW barrel lets me push a couple extra tenths than what others are reporting as max without excessive pressure. I would start at 27.0 and work your way up. I dont think I have ever seen any data from Alliant or any bullet manufacturers for AR Comp for the Grendel. What got me on it was a magazine article I read a while back. I think the guy was using 27.6 grains with a 123 Amax and he got a .60" 5 shot group and a really respectable velocity. So I decided to give it a try and I have never looked back.

[Cornbread]

I will pick the bullet I want to use. Find a suitable powder and do a ladder in.3 grain increments to find max pressure find the node.For example if I decide I want to use the 123 gr sst and 8208 I will source powder or bullet maker data and develop a 1 shot ladder in .3 grain increments. I am looking for max pressure signs and for the accuracy node. I pick a starting load based on available data and am looking for several consecutive powder charges that group in the same vertical plane. Typically you will see a spot where the bullets over a .9 variance in powder charge group together. This is the accuracy node. As you increase powder the impacts will spread out and you will start seeing pressure signs.

[Dt219]