123gr SST over CFE223 in 24" Shilen Overwatch Load Development Data

[apynckel]

Just got back from the range doing a load development with CFE223 and 123gr Hornady SST's out of my 24" Overwatch. This development was done at 100 yards.



Powder range is from 30.5gr-32gr. Batteries in Chrono started failing 1/2 way through the 30.9 string and through the 31.1 string, so lost some data.

Here is what I got...

30.5 2437
30.5 2473
30.5 2460
30.5 2455
30.5 2469
Mean 2458
SD 13

30.7 2473
30.7 2469
30.7 2487
30.7 2464
30.7 2473
Mean 2473
SD 8

30.9 2473
30.9 2478
30.9 2482
30.9
30.9
Mean 2477
SD 4

31.1
31.1
31.1
31.1
31.1

31.3 2530
31.3 2539
31.3 2539
31.3 2544
31.3 2539
Mean 2538
SD 5

31.5 2578
31.5 2588
31.5 2599
31.5 2599
31.5 2599
Mean 2592
SD 8

31.7 2599
31.7 2594
31.7 2583
31.7 2574
31.7 2574
Mean 2584
SD 10

31.9 2619
31.9 2588
31.9 2583
31.9 2604
31.9 2609
Mean 2600
SD 13

32 2619
32 2629
32 2614
32 2629
32 2619
Mean 2622
SD 6

Here is the target. Very bottom target (validate sight in) was the first string of 5, 31.5 grs. Then progressed top left to bottom right. Tightest group was 31.7gr, measuring roughly .295 MOA. I made zero scope adjustments during the entire session.



Strange that the powder charge from 31.5 to 31.7 resulted in zero mean velocity gain.

[Bombtech]

Good shooting!

[apynckel]

Thank ya. Here's a closup of the good grouping.

[Drillboss]

I'd say take that one on the left and be "Happy, happy, happy"!

[LRRPF52]

You have a shooter barrel, that's for sure. Look at what happened at 31.3gr to 31.5gr. You had a significant jump from a mean of 2538fps to 2592fps.

What COL are you using?

[apynckel]

I was running these at 2.255 OAL.

What would you take away from that mean FPS jump?

[NugginFutz]

I have seen similar "anomalies" in my load workups with CFE223, as well.



This is very repeatable in the above barrel, and quite pronounced in another 18" tube, as well. I am not certain what causes this, but it does seem odd, doesn't it?

I just wish my SD's were as good as yours!

[apynckel]

So I have a general question. I'm having a mental struggle on which load I should go with. The 31.7 gr load produced the tightest group, but one of the worst SD's statistically. Is it just the off chance that I squeezed the trigger at the right time to make the group, or do you think that load hit a node?

Also, stupidly I didn't run the suppressor with the load development. Am I going to have to repeat it to ensure I have proper data with the extra mass on the end of the barrel?

Thanks.

[37L1]

I would recommend that you load up more of the ones you are considering and take them out to more distance. That will tell you what you need to know.

[NugginFutz]

As far as SD's go, they should manifest in some form of stringing at the greater distances. Most of the respected load developers recommend nothing closer than 200 yards, with 300 being the most commonly mentioned. Longer range shooting tends to reveal more dramatically the subtleties of variations in MV.

Regarding the suppressor: I see it an opportunity to characterized the rifle, both with and without the can. I can't count the number of times I've read where someone wrote that they (removed/installed) a (name your device) and saw a POI shift of (xx MOA).

If you never, ever intend to shoot the rifle without it, then I suppose you might consider this time wasted for this particular rifle. Me, I would have set out to discover how it does, both with and without, complete with data cards at various ranges, topped off with with twenty seven eight-by-ten color glossy photographs with circles and arrows and a paragraph on the back of each one explaining what each one was.

[pdq5oh]

twenty seven eight-by-ten color glossy photographs with circles and arrows and a paragraph on the back of each one explaining what each one was.

Black & white

[jawbone]

"colored", me thinks

[65Whelen]

If you never, ever intend to shoot the rifle without it, then I suppose you might consider this time wasted for this particular rifle. Me, I would have set out to discover how it does, both with and without, complete with data cards at various ranges, topped off with with twenty seven eight-by-ten color glossy photographs with circles and arrows and a paragraph on the back of each one explaining what each one was.

LOL I'm with you on this, you can never have enough info.

[apynckel]

Man i wish i had enough brass where I could shoot all day, with and without can + ladder workups, and finally a stint at 600 for kicks.

[apynckel]

Just wanted to add in another little tidbit of information. I was seeing zero signs of over pressure on the brass. No cratered primers (though they were getting a bit flat), no brass runout into the extractor / ejector, nothing.