I have encountered a conundrum..

**Mcrider55** · 01-01-2025, 06:05 PM

Doing ladder testing for my Axis Precision 223. Shooting SMK TMK 60gr with 23gr of Alliant 1200r. Cases are all trimmed to 1.75 +/- .001 on my Henderson. CCI400 primers.

Barrel is 24inch Urban rifleman with 1:7 twist and a suppressor.

One group with COL of 2.310 did 8 shots at 1.171 MOA

Another group with COL of 2.340 did 8 at 1.131 MOA.

These were to two best groups shot out of 6 groups tested.

Those in between these two, separated by settings of .05 between them, were farther outside these two.
Why would these two be so close, yet in between be worse? It was a beautiful morning, little wind and 40 degrees.

What say you gurus?

**charlie b** · 01-01-2025, 10:30 PM

I have seen similar before. I'd try a step or two shorter and maybe a step or two longer to see if you have hit on two nodes or just have a 'lucky' group in there. Also look at the group shapes. Fliers, elongated vertically or horizontally? Any pattern to the shapes? Are velocities consistent or do you have a wide ES/SD?

Have you already done a ladder with the powder charge? I usually do that first to find a 'flat spot' in the curve, then I will do a seat depth ladder. I will also repeat a ladder if I feel it isn't 'right' or go up/down in seat depth/powder charge. If nothing else it will confirm the first results. :)

If that was at 100yd I would not be happy. If everything else is done right I'd consider a different bullet. My .223 really likes heavier bullets.

**Robinhood** · 01-01-2025, 10:41 PM

or you could use the COAL length that the bullet manufacturer states and do a ladder test, fine tuning with lenth after finding the best load. My pet load for a 26" 7 twist and an 80 grain SMK with RL15 is 23.7gn. Maybe consider something in the 25gn powder weight. Also that barrel is spinning that short bullet a little fast. Maybe grab some 77gn also.

Good Luck with it Mcrider.

**Stumpkiller** · 01-01-2025, 11:55 PM

My .223 has an ancient twist of 1:12" and I can put 53 gr Sierra #1400 (HP Matchking) in 3/4" at 100 yards all day with CFE223 powder. Keep working on loads.

**Mcrider55** · 01-02-2025, 07:13 AM

Thanks charlie, you understand the two "bumps" or nodes I encountered. I'm going out this morning and shoot a few more groups and see if it is a anomaly or?

Both groups were strung horizontally. I thought about this for awhile and then went and looked again at what I had shot. In my initial post, I had counted all 8 shots. I decided to eliminate the 1 outside "flyer" of the two groups and my numbers changed from a 1.131 to .764.

The other group had changed from 1.171 to .867.

Both group were within .5 inch of a .25 inch "bullseye I was shooting for.

I don't have a chrono yet, still evaluating them. The Caldwell VelociRadar has some interesting features that I like. I've got 2 Garmins on my bass boat and they are outstanding in every way, including their ability to provide updates and all around customer service.

I've only been into this "precision" style of shooting for less than a year after a couple of decades of tactical AR stuff. This is an entirely different world with it's own learning curve, especially with ammunition. I don't shot any type of competition, this is just me trying to get the best results out of what I am using at the time. I had these same 60 SMK's drilling the target with Varget. I also had the same results with 55gr Hornady SP's and R1200. It was encountering these 2 nodes at different seating depths that has me vexed. Never encountered that before.

**Mcrider55** · 01-02-2025, 07:20 AM

Originally Posted by Robinhood

or you could use the COAL length that the bullet manufacturer states and do a ladder test, fine tuning with lenth after finding the best load. My pet load for a 26" 7 twist and an 80 grain SMK with RL15 is 23.7gn. Maybe consider something in the 25gn powder weight. Also that barrel is spinning that short bullet a little fast. Maybe grab some 77gn also.

Good Luck with it Mcrider.

Using the Hornady site, the COAL for this bullet is supposed to be 2.25, which shot like crap. It's a long ways from the 2.34 that looks the best for my rifle.

**Robinhood** · 01-02-2025, 10:52 AM

Originally Posted by Mcrider55

Using the Hornady site, the COAL for this bullet is supposed to be 2.25, which shot like crap. It's a long ways from the 2.34 that looks the best for my rifle.

Shot like crap with what powder weights? Can you reveal how you are performing a ladder test? Like the increments of powder as you work up etc...
When I hang bullets out .90" plus on a short bullet I start watching bullet run out. Honestly, the only thing we have been told is 23 grains of RL15 and your overall length with regards to what your testing. Do you care to share more background?

**Mcrider55** · 01-02-2025, 12:45 PM

Originally Posted by Robinhood

Shot like crap with what powder weights? Can you reveal how you are performing a ladder test? Like the increments of powder as you work up etc...
When I hang bullets out .90" plus on a short bullet I start watching bullet run out. Honestly, the only thing we have been told is 23 grains of RL15 and your overall length with regards to what your testing. Do you care to share more background?

The length of the 60 TMK is .898, the Hornady SP is .722, so it's a significantly longer bullet. My barrel has a free bore 0f 0.06. Case length is 1.75 inches.

After yesterday, I decided it was time to retire my digital Hornady caliper I've used for years and bought a Mitutoyo.

Using the Hornady LNL length gauge, it measures 2.359 to the lands with the Mitutoyo and 2.357.

Went out today and fired 15 shots each at lengths of 2.310 and 2.340.
Temp was 29 degrees, sunny, and zero wind.

Today the 2.340 shots were significantly better than the other. Best 5 shot group was .240MOA, the worst was a .613 MOA

The shorter rounds were a best of .704 and the worst a .987

There isn't much data on Alliant's 1200r for powder loads that I can find, none with bullets above 55gr, so I loaded it up with the 22.9 they recommend for that bullet.

It was much easier to run and gun shooting at 6 inch plates with my AR's!

and a hell of a lot cheaper!!!

**Robinhood** · 01-02-2025, 02:51 PM

Awesome! A lot better than 1.13x.
Did you try incremental powder decrease or increase. Like 22.0, 22.3, 22.6, 22.9 etc..?

**Mcrider55** · 01-02-2025, 05:31 PM

Originally Posted by Robinhood

Awesome! A lot better than 1.13x.
Did you try incremental powder decrease or increase. Like 22.0, 22.3, 22.6, 22.9 etc..?

I haven't. Due to a lack of info on R1200 and heavier bullets, I've stuck with the 22.9 they recommend for the 55gr.

I'm seeing some minor cratering around the firing pin impact on the primer so I think this might be about the max I can/should go.

Thoughts?

**charlie b** · 01-02-2025, 08:01 PM

Without chronograph data it is hard to say. If that load is a max then I'd suggest going down in 0.1 or 0.2 increments a full grain. I bought a Labradar several years ago and it helps a lot. I'd get a Garmin in a heartbeat if I didn't already have the other one.

At least your groups are better.

Yeah, shooting steel is fun, but, it can also hide many things, including shooter errors. My 600yd steel target is a 5in dia plate. When everything is going well it gets boring, and I can get sloppy :) But, when the wind kicks up it is a real challenge.