.223 OCW workup - Looks like crap.

[MustangGreg66]

I've heard from several people, that TAC likes to run hot loads. .

My Wolf primers were cratering/extruding at 25.2, and by 27 it looked like I was going to pierce a primer. No extractor flow though.

Hmm, strange. I guess you're in the right range then. What kind of barrel is it? Is it a purely 223 Rem chamber?

Looking at your results there, I'd say you're right that 23.0, 23.2, 23.4g looks like a node. Much better consistency this time. I'd suggest taking the 23.2gr load and 24.0gr load and shoot some groups to compare.

[BitchinCamaro]

I don't know what kind of accuracy you are looking for or expecting but I know a 3 rd group will not provide much information. it looks like you found something that might work. go and shoot 10 rounds and see what happens.

Again, I'm not looking for accuracy in the standard sense of having nice tight groups. I'm looking for POI stability across a band of charge weights.

As seen from the last target, any off the shelf M193 variant works fine for my 3gun needs, and 24.0 g of TAC surpasses them all in terms of absolute accuracy. Nevertheless, I am probably going to disregard the 24.0g charge because it's not showing POI stability seen in other charge strings...baby out with the bathwater!

Edited September 23, 2015 by BitchinCamaro

[BitchinCamaro]

Mustang Greg, thanks for the second pair of eyes.

The barrel is 18", rifle gas, chambered in .223 Wylde. 1:8 twist 5R rifling.

I just had it reprofiled from Hbar to a much thinnner profile, so I didn't want to post the Mfg. in case it shot like crap by my doing.

Edited September 23, 2015 by BitchinCamaro

[BitchinCamaro]

Data?

I slapped together 5 each of the 23.2g charges with .005" changes in seating depth and headed to the range.

I'm pretty burnt out of the process at this point.

Anyway, I didn't really rush these shots, but I certainly didn't take my sweet time. The flyers may be the charge weight or are probably my crappy shooting- I'm not too concerned at this point because they're all Minute of 3gun and should hold that consistency through various match conditions.

Same 6x scope as last time:

http://i1374.photobucket.com/albums/ag420/OdieF250/OCW%20H-

http://i1374.photobucket.com

Edited September 24, 2015 by BitchinCamaro

[rjacobs]

Like I thought as you got closer to the lands(2.240) the group tightened up. as you backed away from the lands the group opened up a bit. But I dont think you want to run that bullet to far out.

I would explore that 23g area. Probably 22.9 to 23.5 in .1g increments and load at least 5 of each. I would do that at that 2.240 or even try 2.245.

A node should be ~1% from the center so .23g roughly from top to bottom using your 23.2g. So from 23.2 you should still be in the node at 23 and at 23.4 and you throw .1 high and low to see if the group starts to scatter. I believe your next node should be roughly 3% higher. So 3% would be roughly .7g higher than 23.2 which puts you at almost 24g, which wasnt a bad group either IMO. Might explore around there as well(23.9-24.5).

[BitchinCamaro]

Thanks Rjacobs. I'm going to follow that line of reasoning as I chase down the 24.0 grain load.

I'm going to step back for the rest of the week and find a better setup for load testing before I roll into the 24.0 range again. Last night I realized that I sort of half-assed the test cartridges I shot for COAL testing and thought it was unfair to ask the internet for advice if I'm not doing my best to keep my data consistent.

This morning I hand weighed more in 23.2g of TAC at 2.239" and 2.265"COAL

Results:

2.239 COAL- Average: 2666.8 / SD: 23.66

2.265 COAL- Average: 2640.8 / SD: 14.02

Extreme right of the 2.265" COAL group was a called flyer...I swear .

And here are 10 round groups of cartridges loaded on the progressive (close to how I'll have it set up for this load) and some box ammo.

Progressive 23.3g TAC/ ~2.240 COAL - Average: 2647 / SD: 47.52

Wolf Gold .223 - Average: 3061 / SD: 49.45

NOTES:

*With this 6x scope, bag, and buttstock setup, the absolute best I can hold dead steady with parallax and mirage (before the trigger pull) is 1/4 MOA.

*I used Tony's method of loading a magazine with an off-target burner, 5/10 test rounds, and then another off-target burner.

*The 20 round mag I used still touched my shooting mat and created a pivot. I'm not making excuses, but my shots for 2.239"/2.240" had multiple called low pulls of about half a MOA. I'm confident that the vertical stringing was largely due the shooter. I changed around my bags to fully clear the magazine for the 2.265" COAL and Wolf Gold strings, and the vertical dispersion seemed to have shrank. It could also be coincidence but I'm 95% sure it was me.

*~2600 fps is about 200fps slower than I anticipated.

I know the 24.0 load shoots reliably MOA at 6000 feet. After this weekend's match I'll do a mini OCW at that node and see if I can get the velocity and SD I'm looking for.

I'm also going to borrow some 30mm rings and a keymod bipod adapter so I can use my 5x20 power scope.

Edited September 24, 2015 by BitchinCamaro

[BitchinCamaro]

Thank you everyone for your input.

There doesn't seem to be a lot of actual posting of target groups here in Benos so I hope this shows some baseline for the Hornady FMJs using the OCW method.

Edited September 24, 2015 by BitchinCamaro

[Absocold]

With such a low power scope and your stated problems with locking in on the target, I suggest moving to the 50 yard line to remove point of aim errors from the equation. Shorter range helps reduce shifting wind errors too.

[rjacobs]

With such a low power scope and your stated problems with locking in on the target, I suggest moving to the 50 yard line to remove point of aim errors from the equation. Shorter range helps reduce shifting wind errors too.

problem with doing that with OCW testing is that it might not allow enough distance for the group to open up. So you could be in a scatter node, but at 50 yards it looks like its an accuracy node. OCW is supposed to be done at 100 yards minimum if I remember reading Dan Newberry's website right.

Scope magnification isnt the end all be all of shooting good groups. I have shot worse groups at high powers(24x at 100 yards) than if I backed back to say 12x or 8x because I was so jumpy on the trigger and trying to time the pull to slight movement from my heart beat/breathing/hardening of my johnson that I either wouldnt pull the trigger or I would yank the bejesus out of it and throw shots all over. As long as you can keep your cross hairs on your target consistently(and it looks like the OP's targets make this possible) and be consistent in everything else, actually SEEING your hopefully tiny groups isnt all that important and can actually make your group WORSE because now you are trying for that perfect group and things go to hell.

He says he is using a 5x scope(I think) so at 100 yards its like 20 yards. More than enough magnification to hold cross hairs on to the target repeatably.

[BitchinCamaro]

I wasn't especially concerned about the groups as I shot them, I was focused on where the reticle was when the shot broke.

In fact, I caught myself darting my eyes to the right to look for the next target immediately after a shot broke as if I was shooting a plate rack with a pistol. It's probably a bad habit for looking through glass.

I'm not going to really blame my gear, but this AR in particular isn't my ideal up for this kind of repeated shooting. I'm using an ACE tube stock with a second neoprene foam pad, so my cheek bone had a tendency to roll my head out of the eyebox when I tried to get neutral behind the gun. There was a lot of cheek-mooshing to get the right sight alignment, The shooting bag setup wasn't ideal either, especially when there was a mag inserted.

The CMC trigger is a Bill-Drill monster, but is a little dead feeling when you're trying to get repeatable results long range, and it inexplicably develops a "phantom" double stage sometimes when you're really trying to ease the finger pressure. 3 lb trigger, 7 lb rifle.

I know if I practiced more I could compensate for all of this, but that's not what I built it for and shooting this rifle prone is literally feeling like a chore.

It's like building a full on rally-car and only using it to cruise your grandparents down the block to church on Sunday.

In comparison, my bolt gun has a molded kydex cheek piece that acts as a shelf/lock for my face. I could literally fall asleep behind it and still have a neutral hold on the gun with my orbital socket smack dab in the eyebox. 1 lb trigger, 13 lb rifle.

Shooting with a bipod and a single bag to the rear, it's a breeze to lock onto your sight picture at any magnification and break a shot without introducing any tension into the system.

Again, I'm not saying it's the gear that causes me to pull shots, but not having an appropriate setup certainly lets me know what I'm doing wrong when I'm doing it.

Edited September 25, 2015 by BitchinCamaro

[Absocold]

problem with doing that with OCW testing is that it might not allow enough distance for the group to open up. So you could be in a scatter node, but at 50 yards it looks like its an accuracy node. OCW is supposed to be done at 100 yards minimum if I remember reading Dan Newberry's website right.

I'm confused as to what you mean here. Barrel whip is a function of interior ballistics. Once the bullet leaves the gun and exterior ballistics take over, barrel movement no longer has any effect on the projectile no matter what the range. Except for varying external factors that affect bullets like weather and sonic transition instability, groups are identical in MOA's at any distance. Even spin drift and coriolis forces are close enough shot to shot to be ignored in accuracy calculations.

By reducing the distance, the variable parts of external ballistics are reduced and aiming is more precise too. Picking 100 yards as a minimum seems rather arbitrary. But I could be mistaken and I enjoy learning new things, someone help me out if I have it incorrectly.

[rjacobs]

problem with doing that with OCW testing is that it might not allow enough distance for the group to open up. So you could be in a scatter node, but at 50 yards it looks like its an accuracy node. OCW is supposed to be done at 100 yards minimum if I remember reading Dan Newberry's website right.

I'm confused as to what you mean here. Barrel whip is a function of interior ballistics. Once the bullet leaves the gun and exterior ballistics take over, barrel movement no longer has any effect on the projectile no matter what the range. Except for varying external factors that affect bullets like weather and sonic transition instability, groups are identical in MOA's at any distance. Even spin drift and coriolis forces are close enough shot to shot to be ignored in accuracy calculations.

By reducing the distance, the variable parts of external ballistics are reduced and aiming is more precise too. Picking 100 yards as a minimum seems rather arbitrary. But I could be mistaken and I enjoy learning new things, someone help me out if I have it incorrectly.

Its all IMO in reading the OCW nodes and at 100 you have, in theory, larger groups. At 50 yards a scatter node COULD(not saying it would) have 5 rounds touching(and be mistaken for an accuracy node) where as at 100 yards you would have 5 distinct rounds to measure.

Dan Newberry's method(I believe he is the guy that came up with OCW) specifically states 100 yards. If you havent read up on it here is his site:

http://optimalchargeweight.embarqspace.com/#

I also believe the method was designed, compared to the ladder, because most everybody has access to a 100 yard range. I believe most ladder work ups are supposed to be done at 400 or 600 yards(or some crazy ass distance).

Edited September 25, 2015 by rjacobs