Huge ES/SD on Last Load Workup

[Ironman8]

Need some thoughts here fellas.

Recently did a load workup for some 62gr Fusion pulls and had some huge ES/SD numbers.

I’ll update with some actual numbers but I remember that my best SD was 10 and high SD was something like 60. Can’t remembet the ES’s right now. Also, I guess not surprisingly, my best group was the SD @ 10 with a 5-shot ~0.5” group. Most other groups were 1.5-2”.

All bullets were sorted to +/- 0.2 grs.
Brass is mixed mil headstamp (LC, TAA, Win)
Brass was all trimmed to the same length
Bullets all seated on Dillon 550
Powder was TAC and H322 and was weighed & trickle charged if needed (every load)
Primer is Wolf SRM

Only thing I could think of for the variance is the mixed brass but I’ve used this brass without sorting headstamp in the past with some 77gr loads and had some consistent sub-moa ammo.

Thoughts?

[1_click_off]

Did some of your TAC loads get in with your H322 loads?

Was your TAC and H332 all from the same can/lot?

Primers from same lot?

[sjoliat]

I personally would never mix headstamps on anything other than plinking ammo. Start with that.
An SD of 10 isn't exactly bad, but that 60 sounds like a bad charge in a single round. I would think you might have noticed when you fired, that "What the hell was that" moment.
I can't tell you how many times I've had low SD groups print poorly, and mediocre SDs yield half moa or better - especially under 200 yds.
Do you have a shot-by-shot record of velocities? If so, look for a massive outlier in that really inconsistent group.

[markm]

Mixed brass is generally not an issue for .223. But I've come across a few kinds of brass that will mess you up. Most recently, MEN brass. That stuff shoots like 40 fps faster than FC/LC/RP, etc.

A bad chrono read is also possible. When I get a wild ES/SD, I'll look for an individual shot that's way off, and delete that one from the string.

[markm]

The other thing to look out for is WOLF primers with ball powder. I've not had a noticeable issue with TAC, but WOLF SRMs and H335 is a real problem. Bad hangfires like crazy. I just generally don't mix WOLF SRM and any Ball powders. The thing that makes those primers great is the same thing that makes them a bad match with ball powder... (their mildness)

[Krazykarl]

Mixed brass is suspicious. Variance in primer seating can also occur

[Ironman8]

Ok, finally got a chance to sit down and answer some of the questions and look over the data...

1) None of the loads got mixed and all of the powder and primers are from the same lot
2) Didn't feel anything suspicious when shooting the loads...nothing that signaled there was a problem with my charges
3) Yes, shot by shot records...see below
4) I didn't have any hangfires with the Wolf primers but I know what you mean Mark...had that issue with some old mil surplus bulk powder. I may try CCI next time out.
5) Regarding primer pockets, I've been meaning to reach out to you Mark, because I'm using the Hornady reamer/cutter de-crimp tool after seeing you talk about it and I'm not so sure it's giving me consistent results. Wondering if you've noticed that when you ream/cut the pocket straight and bottom out in the pocket, it doesn't actually remove the crimp and the only way to remove enough to seat a new primer is by "wobbling" the reamer in the pocket to cut out the sides of the crimp. Have you had this issue? Not sure if this could be a cause of my inconsistencies?

Now for the data:

Best Fusion/TAC Load
26.0 gr
1- 2721
2- 2737
3- 2732
4- 2749
5- 2726
Avg - 2733
ES - 28
SD - 11
Group Size - 0.523"

Worst Fusion/TAC Load
24.5 gr
1- 2559
2- 2469
3- 2520
4- 2482
5- 2559
Avg - 2517
ES - 90
SD - 42
Group Size - 2.695"

I have all the other loads I tried, but this is just an example of the best/worst examples. Not sure I really see a true one shot outlier in the worst group...that said I did have 4 of the 5 shots within 1.064" and the 5th shot pulled it out to the 2.695" group.


So, I plan to test the brass variability by sorting headstamps by brand and/or year and also have a mixed headstamp group all loaded with the 26.0gr TAC loading since it gave me the best results. I'm curious to see if there's much of a difference between the loadings.

I'll also give CCI or other primers a try with some different TAC loadings to see if I get better consistency and accuracy. What's the protocol with trying a new primer? Start all the way at the bottom of the charge weight or should taking off a grain or so be sufficient?

[Coal Dragger]

Starting a new primer, particularly a hotter primer means starting at the bottom again. At least that is the safe route. Chances are that the hotter primer will not cause any safety issues even if you only drop down 1 grain, but your data set needs to be built with a ladder test at least; and that means running from the bottom up again to find what works with the new primer.

On a side note most rifle rounds I have reloaded for, particularly with ball powders, but also slower burning extruded powders, hate light charge weights. More often than not in order to shoot well I have found that a load density of 90% or more usually gives better results. My loads with CFE 223 for example seem to do best when loaded within a few tenths of a grain of max listed .223 data. Doesn’t matter if it is a 55gr FMJ or a 77gr SMK, until the charge weight reaches enough load density in the case, groups don’t tighten up. I’m not an expert on thermodynamics but my hunch is that some powders just don’t combust as consistently when not packed in pretty densely. I notice a similar trend with your loads using TAC, the bullet and powder are telling you to put the gas to it so to speak.

One of my calibers (.280 Ackley) with 140gr Barnes TTSX has me loading something like a 102% charge density of IMR 4831 for best accuracy, so it’s a compressed load. I’ve even got a .454 Casull that likes compressed loads of H110 under a 300gr bullet, and anything less than 95% density shoots like butt crack ass.

Don’t be afraid to load to the upper end of published data, if you work up incrementally and monitor your brass for signs of excessive pressure.

I also use CCI small rifle primers and have no complaints, ignition has been very reliable.

[bigedp51]

Using mixed brass and how many times the case has been fired effects bullet grip. The neck thickness variations between brands and work hardening of the case neck will play havoc with bullet grip.

The RCBS AR Series .223/5.56 dies have a taper crimp die, and you could try crimping the bullet and see if it improves the ES/SD readings.

You can also try pausing at the top of the ram stroke for 3 to 4 seconds, this reduces brass spring back. This helps keep the case necks from springing back after sizing with work hardened brass.

I use a Redding neck thickness gauge to sort my cases, the cases with uniform neck thickness with the least thickness variations are used for precision ammo. And the rejects are used for practice blasting ammo at shorter ranges.

Below just one quick turn of the wrist will tell you a great deal about the quality of your brass. I have had Remington 233 cases with over .009 neck thickness variations.



I now buy bulk once fired Lake City 5.56 cases at the link below. No more mixed brass and far more uniform brass and this solves many problems.

.223/5.56 - Cleaned, Deprimed & Swaged - LC Only - 500 Pieces $58.00 Free shipping
http://brassbombers.com/223-556-Clea...-2LC-S0050.htm

You can also remove the expander from your full length die and use a Lyman type "M" expander. This can reduce runout when just bumping the case mouth on to the upper .226 part of the expander. This aids bullet seating and helps make more concentric cases. The case mouth will be closed back down and streamlined using a light taper crimp.

[markm]

Regarding primer pockets, I've been meaning to reach out to you Mark, because I'm using the Hornady reamer/cutter de-crimp tool after seeing you talk about it and I'm not so sure it's giving me consistent results. Wondering if you've noticed that when you ream/cut the pocket straight and bottom out in the pocket, it doesn't actually remove the crimp and the only way to remove enough to seat a new primer is by "wobbling" the reamer in the pocket to cut out the sides of the crimp. Have you had this issue? Not sure if this could be a cause of my inconsistencies?

I run my cutter on a drill, and hand prime. If I run the cutter manually and prime on a machine, I get primer seating sticking/stubborn issues. None of this impacts the accuracy. It just drives me nuts. Running the cutter in a drill is definitely fastest and gets you better crimp removal.

Those 2400s velocity shots in the "worst" group could be a bad primer/powder marriage with that 24.5 charge. I bet the 26 gr charge yields a more universal % of powder burned.