OCW Analysis Help and Intro

Greetings community,

I've been a lurker for a few months now. Haven't had too much to contribute beyond the wealth of knowledge already here. However, today I went out and performed, what I’ll call my take on, an OCW method test. This time I got some interesting results I think. I decided instead of trying to interpret it myself, which does not always seem to work out perfectly, I would pool the vast resources of this forum and ask for any and all opinions and advice you can offer.

I put “intro” in the subject as this is my first post here so a bit about me: Grew up in MA shooting BB guns. I am now a PA resident and can finally fully enjoy owning and shooting firearms. In the last year I started reloading and shooting IDPA and am now chasing bugholes with my .223--- my white buffalo, but I certainly enjoy pulling my hair out, kicking myself, chasing the unobtainable, and an endless challenge. What could be more entertaining?

In order to keep this post manageable I’ll save you all some reading and get to my question. If you need more info about rifle, loading techniques, etc, I’ve included it at the end of this post. Without further adieu… My testing procedure: I loaded (10) 3-rnd groups, increasing powder charge by 0.2grns between each group. Feeling adventurous because my COL is so much greater than the book value, I started at a medium charge according to Lyman and Hornady so that I could hit the Lyman accurate load, which is also their max charge weight.

Firing Process: In order to minimize barrel fouling variables, I sprayed barrel with ballistol and ran boresnake through 5 times. I then fired 5 factory rounds to see if POI settled down as well as determine firing rate for temperature to have relatively consistent barrel temp for each shot. This first image shows my 5 factory rounds in the top left fired first. The center image shows my pre test sight-in. Where I then fired 3 out of 6 reloads that I whipped through the progressive in order to get close to target with this bullet/case/powder combo. First round was low, adjusted 3 clicks up (1/4 MOA /click) next two rounds hit low bull. Begin OCW test.

http://farm8.staticflickr.com/7024/6...bb790785_z.jpg


The following image is a composite I made of the OCW (optimum charge weight for anyone wondering) groups. These groups were fired in a round robin, with ~1 – 2 min between rounds depending on how long it took me to completely rebuild firing position after single-loading the next round. These were all shot on a bench, with harris bipod front rest, and rear squeeze sock. I was wearing 4 layers on torso and gloves.

(CAVEAT: If there is one thing I can contribute it is a rear sand-sock that has been working really well for me. I just took a nice wool sock and filled it with brown lentils. It has been working great, nice and smooth hold and the lentils are far lighter than sand and do not escape thru the sock. The shape of them also seems to work really well in supporting the butt of the rifle. Give it a shot, worth a try in a pinch.)

[img width=593 height=768]http://farm8.staticflickr.com/7034/6528758373_c02993070b_b.jpg[/img]

I do everything in my power to try and be consistent with my shooting, but of course I’m sure there is still some piloting issues. But I figure, “if this is how I’m gonna shoot, might as well get some practice while I test. Who cares if all my data is erroneous?” I’m only partially kidding when I say that. I hope that the results of this test and my control groups can illustrate that I’m a decent enough shot to at least have a hope and a prayer at figuring some of this out. I guess now is as good a time as any to say that I don’t have a chrono, so my apologies, I cannot give you velo data or SDs at this time.

The main reason I was inspired to post this was because of some of the unique patterns I saw in the groups. I won’t go too far into what I see because the main purpose of this post is to get your input, however some things just jump off the page for me. Vertical on groups 4, 7, 8 with the horizontal of 5 in between !?! Very similar pattern on groups 1 & 6 with ~0.5” elevation change? Almost perfect doubles plus fliers on 8 & 9. FYI, round 1 of the tenth group exhibited pressure signs I was not a fan of and did not continue to shoot them. Even if it were accurate I would not want to shoot that regularly in my rifle, so it’s moot.

I’ve also included some overlays, mostly for fun, although it was neat to assemble. The bottom left two targets are a compilation of all shots fired. The leftmost one I’ve erased all outlines as if they were fired on as single group. The second from the left shows the outlines of the bullet holes. The bottom two right targets show the groups 1-4 and 5-7, respectively. While the aggregate is an OK group, I’m still looking for a single hole. Perhaps I need to dump some more money into this rig and/or tighten up my reloading skills.

After the 9 groups were fired, I fired 3 more of the 24 gr loads at the center target of the first image to confirm that accuracy did not go to heck due to a fouled barrel. They were still very near the first 2 post-sighter shots. Finally, I shot 5 more rounds of the factory BHA to re-confirm that fouling was not a problem and to prove to myself that after 2 hours my shooting didn’t go to hell in a handbasket. Aslo, FWIW, the final rounds in the top right target of the first image were loaded in magazine and fired as fast as I could, under 20 seconds.

Well, I apologize for the extremely long post. I look forward to hearing what you guys have to say. And thought that at least maybe someone would be entertained in a cruel, sick, twisted way in my results as I am.

Thanks in advance for your help and reading the obnoxiously long post, I really enjoy this forum, I don’t have a flame suit but I do have access to one rated for 50KVA,

Andy




About the stick: Savage 10 FCP, .223 Rem, almost completely stock, riding in a Choate tactical stock, slight trigger clean up (by me), harris bipod, Hawk 6.5-20 x42mm Optic. Approx 300 rnds through factory 1:9” twist varmit contour 24” bbl. Action/barrel has been removed from stock once to clean up trigger. Action screws re-tightened hand tight in increments to attempt even torque; I do not have a torque rench—this is not an accustock, think this one is as picky about torque as the accustock? Action is pillar-bedded and appears to have very solid bedding contact.

…because I know it doesn’t count if there aren’t pics ;) (this was not the day of test but during the freak Oct. snow storm)

[img width=573 height=768]http://farm8.staticflickr.com/7026/6529000461_20bd7bff4d_b.jpg[/img]

About the rounds: 69gr Nosler Custom Competition BTHPs in Black Hills Ammo reloaded cases. FL resized, trimmed to length, chamfered, deburred, primer pocket cleaned, flash hole deburred, neck brushed, and weight sorted so that all 3 rnd groups are within 0.1 grn. Primers and bullets NOT weight sorted.

Rounds loaded on RCBS progressive press w/ standard RCBS dies. No crimp. Run through press one by one i.e. used as a single stage. Primed cases are tared on scale, charge is dropped from uniflow measure, then weighted on a cabela’s electronic scale in case. I’m meticulous in gauging/avoiding the scale’s drift, sometimes re-weighing charges 4-7 times while re-zeroing scale.

COL is determined with Hornady gauge off ogive to be 0.002” – 0.003” back from where bullet hits in chamber/barrel. I don’t want to say the lands because when I pull the bullet from the rifle I do not see marks from the lands.

Hello albinomonki, it looks like you have everything well under control. I would work with the number 6 load adjusting the seating depth and see if it will print that one hole group your looking for.

Hello albinomonki! Welcome to the forum! The only advice I can offer is simple: Shoot! Grin! Repeat! And try to learn something every time!
Btw, your range looks cool with the snow. We don't get much of that down here!

I'd consider going with either #3 or #6, as both those seem to be roughly the center of a node.

I'd say the vertical is likely either due to bipod "hop" or the rifle wants a different or more consistent shoulder pressure applied. The bipod hop can be helped by leaning into the rifle more, which pushes forward and "preloads" the bipod. Or, if you're shooting free-recoil, try holding the rifle more tightly to the shoulder.

FWIW, I rarely use a chrono for load development either. And I typically use a ladder or modified OCW to test loads also.

And welcome to the forum :)

I'd take a second look at 5 and consider wind or trigger technique. ;)

Gentlemen,

Thanks for the welcome and insight. Sqirrelsniper, interesting that you brought up shoulder pressure/bipod hop; that is one of the things i try to be the most conscientious about while i'm shooting. I think at this point i can say that the rifle prefers a solid shoulder press as opposed to free-recoil. I do pay attention to my shoulder pressure but i have a feeling the only thing i'm achieving is thinking about it... not sure i've got enough trigger time to really know if i'm doing it right. I mentioned all the layers i was wearing half hoping someone would address my shooting technique, even though you've never seen me shoot i'm amazed you called that out right away.

As for preloading the bipod, i've read a bit about that but am having trouble getting the hang of it. What i run into is when i try to lean into rifle the feet of the 'pod roll in their tubes and the gun walks back away. Any suggestions? Perhaps putting some sort of stop in front? I may also try those three loads again shooting off a pack instead of the bipod; might be a good way to rule out my bipod management. I find that when i'm trying to preload the rifle/bipod, in order to not get it to walk back away i have to apply rearward pressure with either strong or weak hand. This in turn puts tension in my bicep which i try to avoid. Is rearward pressure normal/OK? I know, i'm going off-topic on my own thread... for shame.

barrel-nut: i've got the grinning down to a science for sure... although it's often more of a smirk of confusion as to why load X was great last week but garbage this week. That snowy day was a gift... i sat there all alone just listening to the flakes hit the brim of my hat and trees snapping and falling all around. Unfortunately, when i got home I had no power, and it stayed that way for a week. Win some, lose some :-\

http://farm8.staticflickr.com/7017/6...c4e0de61_b.jpg

DanSavage et.at.: when working with seating depth, what kind of increments should i try? Also,just to check, when someone talks about jamming into the lands does this mean taking my OAL as determined by Hornady gauge and then seating my bullets at a longer length? Read a few things about savages enjoying jammed .223 rounds.

Eric, my trigger technique is flawless! Must have been wind... oh wait, there was ZERO wind that day. Seriously though, are there any other causes of perfect horizontal like that i could look into? I have never had a group look like that before. Although, now that i think about it i almost always shoot 5 shot groups. Throw 2 more rounds of questionable shooting in there and we have another great/mediocre/lousy group and/or flyer situation.

Thanks for the advice, i look forward to some more!

-Andy

Quote:

---

Originally Posted by albinomonki

As for preloading the bipod, i've read a bit about that but am having trouble getting the hang of it. What i run into is when i try to lean into rifle the feet of the 'pod roll in their tubes and the gun walks back away. Any suggestions? Perhaps putting some sort of stop in front? I may also try those three loads again shooting off a pack instead of the bipod; might be a good way to rule out my bipod management. I find that when i'm trying to preload the rifle/bipod, in order to not get it to walk back away i have to apply rearward pressure with either strong or weak hand. This in turn puts tension in my bicep which i try to avoid. Is rearward pressure normal/OK? I know, i'm going off-topic on my own thread... for shame.

---

I typically shoot from prone with a bipod, with the bipod feet placed onto bare soil. I then work the bipod/rifle back and forth a few times to kind of "dig in" the feet. You don't have to have the bipod capable of completely supporting your weight, but it shouldn't scoot forward as soon as you start leaning into the rifle. A lot of shooting mats now have a "bipod strip" of fabric sewn into them near the front to kind of catch the bipod legs and keep the bipod from scooting forward. I've also seen guys clamp small strips of wood onto a bench to keep the bipod from scooting forward, but I've never personally tried that method, so I don't know if it actually works well or not.

I typically use my support hand (left, since I'm right-handed) turned back under the butt of the rifle, then use my thumb and index finger to keep the stock seated into my shoulder, all the while using the other three fingers to squeeze the rear bag. With the rifle held into my shoulder as such, I then lean some weight into the butt of the rifle with my shooting shoulder, which preloads the bipod.

Shooting well from a bipod is certainly an acquired skill, as it adds another element to the shooting process. Most people do find it easier to shoot good groups from a sandbag-style front rest or something like a rucksack. Bipods can certainly provide excellent groups, but there is definitely a technique to it.

I'd run another test from 25.1-25.5 in 0.1gn increments and see if that node is consistent.

As far as loading the bipod, if you shoot prone, a good shooting mat will have a strap across the mat near the front end to catch the bipod legs and give you something to load against.

Quote:

---

Originally Posted by albinomonki

Eric, my trigger technique is flawless! Must have been wind... oh wait, there was ZERO wind that day. Seriously though, are there any other causes of perfect horizontal like that i could look into? I have never had a group look like that before. Although, now that i think about it i almost always shoot 5 shot groups. Throw 2 more rounds of questionable shooting in there and we have another great/mediocre/lousy group and/or flyer situation.


-Andy

---

Side of the barrel touching the stock slightly, inconsistent cheek weld or head position (giving you a slightly different view through the scope each time) could also do it but you would probably see it in the other groups too.

I find that taking the OAL with the Hornady gauge and adding about .015 works good then I pick the load with the most consistent groups then I seat the bullets shorter by .005 at a time for each group. I've gone back to about .040 off the lands as long as I'm not pressing the the bullet into the case too far and making sure I'm not creating a compressed load. A compressed load is when your using a certain powder that fills the case near full and you seat the bullet down crunching and compacting the powder. Compressed loads are ok as long as it has been worked up to with no pressure signs, and they can also be very accurate.

I would not increase your OAL from what it is now unless you work the charges back up from starting point, just for safeties sake. That is why I always jam them pretty good right off the bat so I only have to go in (away from the lands) for final testing. Most of my loads are in the lands or just off.
I'll try to find this one picture I've got on here somewhere that demonstrates what a difference seating depth can make.c

By the way that is a nice very nice accurate rifle and some excellent shooting!

Merry Christmas to everyone!

Dan

This is a picture of my first seating depth test. The load I settled on was actually just touching the lands in which I established by using the Hornady gauge and it'l shoot bug holes.


http://i1011.photobucket.com/albums/...yAlbumb099.jpg

Since then I test in smaller increments, and disregard point of impact for each group in relation to aiming point because I was adjusting scope down for a 100 yard zero.

Quote:

---

Originally Posted by DanSavage

"Shot a woodchuck @ 175 yds w/3rd Bullet"

---

nice... i don't reload and don't have much to add to the thread, but it looks like fun!

Quote:

---

Originally Posted by Eric in NC

I'd take a second look at 5 and consider wind or trigger technique. ;)

---

Totally agree... look at 5 first. Retest and use 10 round groups and +- .1gr each side of the charge for #5.

Looks like groups 3 and 7 are least sensitive to charge variation but group 5 is the smallest. With single, 3 shot groups, it's hard to know if group 5 really is the most accurate or if you just got lucky.

If you're going to throw charges without individually weighing, I suggest working on groups 3 and 7 for further load development. If you're going to weigh each charge, I'd work on group 5.

If you want to cover all bases, I'd make the next round of load development an OCW test with charges from #3 to #7 in 0.1 gr increments.

Keep in mind if you're using long range bullets they may not fully stabilize until after 100 yds.

in my LRPV, same powder/bullet, 25 to 25.3 gave me .30 groups at 100

A type of trivia if you like. A snippet of info stolen from "Secrets of the Houston Warehouse" Google it if you like. Interesting read.
Both horizontal and vertical dispersion can be tuned out of a tuned rifle by slight seating depth adjustments.
Its worked for me since I was a rookie.

One caveat right back at ya. Virgil shot a 6 and 22 PPC. I only have a 6. Never seen it shoot well without being loaded into the lands to some extent.
Your rifle and chosen bullet would probably prefer more of a jump. Just my opinion on starting points and your test does NOT back me up on that ;D

Vertical can be fixed by moving closer/deeper into the lands.
Horizontal can be tuned out just the opposite.
Pick your velocity and desired pressure level and start tweaking. .003" increments at a time only.
I see plenty there to play with. Your close. Nice shooting.