223 OCW Analysis Help

[AeroEngi]

So I finally got a chance to go to the range and test my loads for my SPR chambered in 223 Wylde. I ran an OCW test at 100 yards using Lake City brass, CCI BR-4 primers, 77 gr Nosler Custom Competition projectiles and Varget. I loaded them all with a very light crimp using a Lee Factory Crimp Die at an OAL of 2.260".

I wish my results were more conclusive so I'm turning to you guys for some advice/help.

The charge weights and location on the target are as follows:

Top Target (First Picture)
Top left diamond 22.9
Top right diamond 23.2
Center diamond 23.5
Bottom left diamond 23.7
Bottom right diamond 24.0

Bottom Target (Second Picture)
Top left diamond 24.3
Top right diamond 24.6

Ignore the bottom left diamond in the second picture. Those were my fouling shots before I started the test. All shots were fired from a lead sled.





I personally think there is a node between 23.7 gr and 24.3 gr but I really like the grouping of 23.2. Unfortunately there doesn't seem to be a node there.

Also, what would be my next step? Assuming I find a node, what would I have to do next to shrink my group sizes?

Let me know what you guys think. Any help or advice would be greatly appreciated.

[Wrangler John]

Sometimes primer choices make a big difference. The photo below shows the difference between two loads in the same rifle, same bullet, cases and powder charge, the difference is between Federal 205M and Winchester Small Rifle Primers (WSR). When working up a load I use several primer brands: Remington 7-1/2 BR; Federal 205M; Winchester WSR; CCI BR-4 and Wolf 223 Remington Small Rifle Primers. The Wolf primer works exceedingly well with some powders. Then there's primer seating - inconsistencies there can mess up a group.



My preference is for commercial brass, Winchester, Nosler, Hornady, Remington or Privi-Partisan in that order, with Winchester the go-to product when available.

The other thing is that some powder and bullet combinations are better than others in any given barrel and twist. I know the Nosler 77 grain Custom Competition requires a 1:8" twist or faster.

I don't crimp bullets for the .223 Remington or 5.56x45 NATO, it's just another variable dependent on case length, and isn't needed in most instances for target or competition use. If you are using the Nosler 77 grain Custom Competition Bullet without the cannelure (part #53064), then there is some chance of distorting the jacket more than using the bullet with a cannelure (part #53033). All bullets stay put in my Colt M-4 H-Bar Elite without a crimp.

Nosler's latest manual lists the accuracy load for the 5.56x45 NATO using the 77 grain Custom Competition Bullet as using RL15 powder, over Winchester WSR primers in a Nosler case, and fired in a 20" 1:7" twist Pac-Nor barrel. You have probably already tried Berger's 73 grain Match BT Target and 75 grain Match VLD Target bullets for comparison.

That's about all I know, except when groups look like someone dropped ball bearings on the floor, it's usually me doing something wrong or completely silly.

[AeroEngi]

Sometimes primer choices make a big difference. The photo below shows the difference between two loads in the same rifle, same bullet, cases and powder charge, the difference is between Federal 205M and Winchester Small Rifle Primers (WSR). When working up a load I use several primer brands: Remington 7-1/2 BR; Federal 205M; Winchester WSR; CCI BR-4 and Wolf 223 Remington Small Rifle Primers. The Wolf primer works exceedingly well with some powders. Then there's primer seating - inconsistencies there can mess up a group.



My preference is for commercial brass, Winchester, Nosler, Hornady, Remington or Privi-Partisan in that order, with Winchester the go-to product when available.

The other thing is that some powder and bullet combinations are better than others in any given barrel and twist. I know the Nosler 77 grain Custom Competition requires a 1:8" twist or faster.

I don't crimp bullets for the .223 Remington or 5.56x45 NATO, it's just another variable dependent on case length, and isn't needed in most instances for target or competition use. If you are using the Nosler 77 grain Custom Competition Bullet without the cannelure (part #53064), then there is some chance of distorting the jacket more than using the bullet with a cannelure (part #53033). All bullets stay put in my Colt M-4 H-Bar Elite without a crimp.

Nosler's latest manual lists the accuracy load for the 5.56x45 NATO using the 77 grain Custom Competition Bullet as using RL15 powder, over Winchester WSR primers in a Nosler case, and fired in a 20" 1:7" twist Pac-Nor barrel. You have probably already tried Berger's 73 grain Match BT Target and 75 grain Match VLD Target bullets for comparison.

That's about all I know, except when groups look like someone dropped ball bearings on the floor, it's usually me doing something wrong or completely silly.

Thanks for the elaborate explanation! I really appreciate it.

I would think that the BR-4 primers that I'm using would be adequate considering that they're "match" primers and are supposed to be more consistent. I tried my best to seat the primers as consistent as possible. I cleaned out the primer pockets on each of the cases and seated the primers using a Hornady hand priming tool.

The reason why I'm using Lake City brass is because I have a lot of it and I've read that many people have used it with this type of load with great success.

I crimp because I want to keep neck tension as consistent as possible. Again, I only applied a very light crimp. I used a Lee Factory Crimp Die so a cannelure is not necessary.

I have another set of the same exact loads that I used for this OCW test. I'll rerun the test using these loads to confirm the potential node at 23.7-24.3. If the node is confirmed, then I'll make another batch from 23.6-24.4 in 0.2 gr increments and see what that tells me. Does this seem like a sound strategy?

[Metal God]

Someone needs to explain to me why the smallest group is not the best load .Don't link Dan's web page . Been there don't get that . I just went to the range yesterday and worked up loads for my N.M service rifle . My best group was .85 moa at 100yds the group was 10 shots


77gr SMK
IMR 4895
LC-14 cases
CCI # 400 primers

Which of the first three groups is my OCW the 4th ( bottom right ) is/was a Federal GMM control sample

thanks MG

[smalltime]

snip

I'd go with 24.2gr, play with seating depth and try without the FCD.

[JMP]

OCW is for avoiding barrel whip when the projectile is leaving the muzzle. It's more useful with longer barrels and larger loads that cause more vibration. With a 77gr and 20 some grains, I'd first look at other issues that drive inconsistency. It's my opinion that the OCW test has become over-used with barrels and loads that don't necessarily warrant it.

[Metal God]

Interesting if true . My rifle is a 13lb A3 or 4 style rifle with a 20" HBAR .I get confused as to what's the difference is . Mine's a flat top with carry handle and A2 stock . My barrel in 1" thick from chamber to front sight base 12" then drops just about straight down to .75" the rest of the 20" (8") . The barrel is completely free floated using a Rock River NM free float sleeve . I used high temp sleeve retaining compound between the barrel ex and receiver when securing the barrel to the receiver . There should be very little whip in the barrel .

But still how do you read a node ?? I know if you see your group string or look like the bullets are in a line that"s not a good thing . My 23gr group looks pretty round with one flier . The 23.5gr group looks to be a more consistent group only because there in not an out lier/flier but using a 77gr bullet in an AR that must use a mag for some of the stages in competition I don't have much of a choice as to seating depth . I'm at mag length right now and don't think I should consider seating that long of a bullet deeper . The load is already compressed . I can here the powder go crunch when seating the bullets .

[AeroEngi]

OCW is for avoiding barrel whip when the projectile is leaving the muzzle. It's more useful with longer barrels and larger loads that cause more vibration. With a 77gr and 20 some grains, I'd first look at other issues that drive inconsistency. It's my opinion that the OCW test has become over-used with barrels and loads that don't necessarily warrant it.

How is the OCW test more useful with longer barrels and larger loads?

With the OCW test method, my understanding is that you're basically shooting for groups but you're using the round-robin method of shooting groups which helps minimize shooter error, inconsistencies due to the environment, barrel temperature and fouling buildup. It minimizes the statistical error associated with shooting a group with one charge, then shooting another group with a heavier charge, so on and so forth. I don't see how it can it can only be more beneficial to longer barrels and larger loads.

[AeroEngi]

Interesting if true . My rifle is a 13lb A3 or 4 style rifle with a 20" HBAR .I get confused as to what's the difference is . Mine's a flat top with carry handle and A2 stock . My barrel in 1" thick from chamber to front sight base 12" then drops just about straight down to .75" the rest of the 20" (8") . The barrel is completely free floated using a Rock River NM free float sleeve . I used high temp sleeve retaining compound between the barrel ex and receiver when securing the barrel to the receiver . There should be very little whip in the barrel .

But still how do you read a node ?? I know if you see your group string or look like the bullets are in a line that"s not a good thing . My 23gr group looks pretty round with one flier . The 23.5gr group looks to be a more consistent group only because there in not an out lier/flier but using a 77gr bullet in an AR that must use a mag for some of the stages in competition I don't have much of a choice as to seating depth . I'm at mag length right now and don't think I should consider seating that long of a bullet deeper . The load is already compressed . I can here the powder go crunch when seating the bullets .

You're not looking for tight groups in the OCW test, that comes later. You're looking for a set of charges that have an average point of impact that is relatively the same. For example, if you look at my pictures and observe the targets shot at 23.7 gr, 24.0 gr and 24.3 gr, all three have approximately the same point of impact. This implies that there is a potential node within this range that is insensitive to small variations. What the OCW (Optimal Charge Weight) does is it gives you a charge weight that is insensitive to small variations in charge weight, bullet weight and primer inconsistencies.

Hope this helps.

[Metal God]

So in my pic that would be 22.5 gr and 23 gr having the same POI and the 23.5gr target POI moving up and over towards the bull ?

Good call I forgot about the round robin part

Two questions on that

1) If your barrel is well fouled 50+ rounds through the rifle and you let the barrel cool completely between groups during load developement . Does the round robin idea still hold true .

2) If working up loads that you not only shoot one shot per minute . You will also have a rapid fire stage where you shoot much quicker heating up your barrel . I'd think when doing load development ( at least for me and this rifle ) I'd need to avoid the round robin method and shoot more like I would for the rifles intended purpose ?yes?

[AeroEngi]

Good call I forgot about the round robin part

Two questions on that

1) If your barrel is well fouled 50+ rounds through the rifle and you let the barrel cool completely between groups during load developement . Does the round robin idea still hold true .

2) If working up loads that you not only shoot one shot per minute . You will also have a rapid fire stage where you shoot much quicker heating up your barrel . I'd think when doing load development ( at least for me and this rifle ) I'd need to avoid the round robin method and shoot more tike I would for the rifles intended purpose ?yes?

1) You don't let the barrel cool completely. You just try to keep the barrel at as much of a consistent temperature as possible. For me, 30 seconds between shots works really well.

2) In that case, you can still use the round-robin method to minimize other errors but don't wait between shots so your barrel still warms up. Also, if you have a properly stress-relieved barrel, then shooting with the barrel hot or cold shouldn't really matter much.

[JMP]

How is the OCW test more useful with longer barrels and larger loads?

With the OCW test method, my understanding is that you're basically shooting for groups but you're using the round-robin method of shooting groups which helps minimize shooter error, inconsistencies due to the environment, barrel temperature and fouling buildup. It minimizes the statistical error associated with shooting a group with one charge, then shooting another group with a heavier charge, so on and so forth. I don't see how it can it can only be more beneficial to longer barrels and larger loads.

When the charge is ignited, it causes a wave to oscillate along the barrel. The intent of the OCW test is for the projectile to exit the muzzle when the steel of the muzzle is in its lowest energy state. If the projectile and the barrel's shockwave align so that the shockwave and the projectile pass through the muzzle at the same time, it will provide the potential for the most possible disruption when the projectile leaves the barrel.

However, in very rigid barrels (generally short and/or very heavy), the shockwave will have much smaller effects. The best precision barrels are build with extreme rigidity and have a contour that best dampens the effect of the wave.

AR-15 type guns tend to have very short rigid barrels and use a mild charge, so the adverse effects of wave resonance isn't that great. Therefore, in some rifles, performing extensive OCW tests is not of a significant advantage. In most cases, the results are inconclusive because a poor sample is often caused by shooter error or imperfections and limitations of one's firearm. Also, for shooting groups, a good optic is needed to confirm that the point of aim is identical for each shot.

In the case of the pictured groups, there seems to be too much vertical dispersion in all cases to ascertain any conclusive results.

[AeroEngi]

When the charge is ignited, it causes a wave to oscillate along the barrel. The intent of the OCW test is for the projectile to exit the muzzle when the steel of the muzzle is in its lowest energy state. If the projectile and the barrel's shockwave align so that the shockwave and the projectile pass through the muzzle at the same time, it will provide the potential for the most possible disruption when the projectile leaves the barrel.

However, in very rigid barrels (generally short and/or very heavy), the shockwave will have much smaller effects. The best precision barrels are build with extreme rigidity and have a contour that best dampens the effect of the wave.

AR-15 type guns tend to have very short rigid barrels and use a mild charge, so the adverse effects of wave resonance isn't that great. Therefore, in some rifles, performing extensive OCW tests is not of a significant advantage. In most cases, the results are inconclusive because a poor sample is often caused by shooter error or imperfections and limitations of one's firearm. Also, for shooting groups, a good optic is needed to confirm that the point of aim is identical for each shot.

In the case of the pictured groups, there seems to be too much vertical dispersion in all cases to ascertain any conclusive results.

Interesting. Thanks for the explanation. That totally makes sense. I have a question though. If not using the OCW test, what other test would you recommend?

[JMP]

Interesting. Thanks for the explanation. That totally makes sense. I have a question though. If not using the OCW test, what other test would you recommend?

For a new setup, I generally pick the three most favorite powders for the load. Then, I set charges, high medium, and low. Then, I refine from there, using adding a bit more powder to see how hard I can push the bullet. In the end, I will choose a load based on where I get the most accuracy with the least amount of deviation in velocities.