I was at the range on Saturday (3/25/2017) and did some workup loads using the OCW method.  Can someone please help me with reading the groups so i know what my optimal load is?

Here are the specs on the barrel:

Rainier Arms Select Series MEDCON 16" Medium profile
Barrel Length: 16"
Gas Block Seat: .750
Rifling: Polygonal 5 Groove
Weight: 30.4 oz
Stainless Steel: 416R
Feed Ramps: M4
Gas System: Midlength
Chamber: 5.56MM
Finish: Matte Stainless / Black Oxide
Twist: 1X8


Load:
223 Remington
Lake City 5.56mm NATO brass (mixed years) (i'll have to check the trim length)
CCI Small Rifle Primer
IMR 8208 XBR
COAL:  2.260" (no crimp)

I fired at eight targets (100 yards) using powder graduations of 0.2 grains, starting from 23.0 and up to 24.4 grains.  3 rounds to sight in at 23.0, 23.6, and 24.2.  It was kind of windy with the wind blowing from right to left.

I wrote down the center to center measurements for all of the groups right next to each group.  I didn't recall having any fliers.  For reference, the black X-ring is 1" in diameter and the next ring is half an inch larger in radius.



NOTE:  please ignore the two Black Hills test loads (68gr Heavy Match HP, and 69gr Sierra MatchKing) and the Ruger American Rimfire groups,



below is a pic of the brass I used.  at 24.4gr, i saw a very small amount of cratering in one primer.  the rest of the primers were all pretty flat.

I've been playing around with the OnTarget software. Personally, I think 3 is not enough data, most say 5. I say 10 to get a good statistical curve but I shoot 20 because I'm interested in consistency and it's fun. As someone previously mentioned, you're supposed to have wide groups tightening up until you hit the node then spreading out again. I'm not seeing that in the data. I assume you're at 50 yards.

Hogdgon says max load is 23.8 so I expect your higher loads to be really hot, but those seem to be your tightest groups.

I've been playing around with the OnTarget software. Personally, I think 3 is not enough data, most say 5. I say 10 to get a good statistical curve but I shoot 20 because I'm interested in consistency and it's fun. I assume you're at 50 yards.

Hogdgon says max load is 23.8 so I expect your higher loads to be really hot.

hopefully, his longer COAL he is using will take off some of that pressure, and it appears he is paying attention to his pressure signs

also agree that higher shot counts would better represent group size (but not  20  )

also agree that higher shot counts would better represent group size (but not  20  )

I know. I'm weird like that.   

this was shot at 100 yards at kokohead.

also, can someone else correct me if i'm wrong, but i thought the OCW method only calls for 3 shot groups per target.

i'm okay with just shooting 5 shot groups, but i was hoping that the OCW method would produce more relevant results.

this was shot at 100 yards at kokohead.

also, can someone else correct me if i'm wrong, but i thought the OCW method only calls for 3 shot groups per target.

i'm okay with just shooting 5 shot groups, but i was hoping that the OCW method would produce more relevant results.

Check the instructions here
http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134

I was at the range on Saturday (3/25/2017) and did some workup loads using the OCW method.  Can someone please help me with reading the groups so i know what my optimal load is?

Here are the specs on the barrel:

Rainier Arms Select Series MEDCON 16" Medium profile
Barrel Length: 16"
Gas Block Seat: .750
Rifling: Polygonal 5 Groove
Weight: 30.4 oz
Stainless Steel: 416R
Feed Ramps: M4
Gas System: Midlength
Chamber: 5.56MM
Finish: Matte Stainless / Black Oxide
Twist: 1X8


Load:
223 Remington
Lake City 5.56mm NATO brass (mixed years) (i'll have to check the trim length)
CCI Small Rifle Primer
IMR 8208 XBR
COAL:  2.260" (no crimp)

I fired at eight targets (100 yards) using powder graduations of 0.2 grains, starting from 23.0 and up to 24.4 grains.  3 rounds to sight in at 23.0, 23.6, and 24.2.  It was kind of windy with the wind blowing from right to left.

I wrote down the center to center measurements for all of the groups right next to each group.  I didn't recall having any fliers.  For reference, the black X-ring is 1" in diameter and the next ring is half an inch larger in radius.



NOTE:  please ignore the two Black Hills test loads (68gr Heavy Match HP, and 69gr Sierra MatchKing) and the Ruger American Rimfire groups,



below is a pic of the brass I used.  at 24.4gr, i saw a very small amount of cratering in one primer.  the rest of the primers were all pretty flat.

Just curious what your source for the loads is? Book? Internet? If so which book or link? If you don't remember would you just tell me what the range of powder is (low to high)? Thanks!

24.4 APPEARS TO BE YOUR BLUEBERRY , BUT AS YOUR BRASS WAS FROM DIFFERENT LOTS, HARD TO TELL.
TRY USING ALL THE SAME LOT BRASS OR AT LEAST WEIGH YOUR BRASS TO GET A BUNCH THAT ARE SAME OR SIMILAR.
YOU CANNOT COMPARE APPLES WITH ORANGES

Check the instructions here
http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134

So if I read it correctly.
1) Use 5 to 7 targets at 100 yards.
2) Shoot up to 25 total rounds to avoid fouling.
3) "Triangulate" the results for each target.
4) Choose 3 best target results and pick the average.
5) Enjoy!

Generally, the results should be as such.
"You will now look for the three groups which come the closest to hitting the same POI (point of impact) on the targets. The trend of the groups should be obvious, normally going from low and favoring one side, to high and favoring the other side. But along the progression, there should be a string of at least three groups that all hit the target in the same relative point."

IMHO, the brand of brass doesn't make a difference as long as the COAL is the same and the bullets and powder load are the same. Bullet length and weight are equally important so I use a scale and caliper to check.

Just curious what your source for the loads is? Book? Internet? If so which book or link? If you don't remember would you just tell me what the range of powder is (low to high)? Thanks!

long answer short:  i gathered my info from quite a few places.  i have the Hornady 9th, but it doesn't list 8208 XBR.  I guess you could say that choosing my max charge was a little bit of (a well-researched and) an educated guess.

i didn't save many of my links, but here is one of them:
http://www.njgunforums.com/forum/index.php/topic/81132-223-bullet-question/

at least a couple of times other reloaders have mentioned that 8208 XBR gives better accuracy above the published maximums.  a lot of the load data that was available was for 223 Rem chambers so you'll see that the loads are dialed back given the limitations of the throat and the brass.

8208 XBR in its current form is relatively new to the market so there isn't a whole lot of info on it.  the good thing is that it is supposedly a rebranded military powder from Australia so there is some amount of data for it.

I tried to find powders with similar burn rates and profiles (short extruded) and compared the load data to the velocities achieved and the rifle used.  for the times that i was able to find 8208 XBR data, but not specifically for the Hornady bullets, i compared the loadings for the 69 SMK and the 77 SMK.  the Hornady supposedly has a profile that is more similar to the 77 SMK, but it is obviously 1gr lighter than the 69 SMK.

i also made two sets of workup loads, which i shot a few weeks prior.  each set was 10 rounds total with each round increasing in 0.1gr increments from 23.6 to 24.6.  i fired these through two different rifles to test the upper limit of the load.  after every shot, i checked for pressure signs.  the pressure testing loads were measured on a hornady auto dispenser.

at least a couple of times other reloaders have mentioned that 8208 XBR gives better accuracy above the published maximums. 

That seems to match your results. I'd say 24.0 gn is the best load since it's only 0.2 gn above the published max.

long answer short:  i gathered my info from quite a few places.  i have the Hornady 9th, but it doesn't list 8208 XBR.  I guess you could say that choosing my max charge was a little bit of (a well-researched and) an educated guess.

i didn't save many of my links, but here is one of them:
http://www.njgunforums.com/forum/index.php/topic/81132-223-bullet-question/

at least a couple of times other reloaders have mentioned that 8208 XBR gives better accuracy above the published maximums.  a lot of the load data that was available was for 223 Rem chambers so you'll see that the loads are dialed back given the limitations of the throat and the brass.

8208 XBR in its current form is relatively new to the market so there isn't a whole lot of info on it.  the good thing is that it is supposedly a rebranded military powder from Australia so there is some amount of data for it.

I tried to find powders with similar burn rates and profiles (short extruded) and compared the load data to the velocities achieved and the rifle used.  for the times that i was able to find 8208 XBR data, but not specifically for the Hornady bullets, i compared the loadings for the 69 SMK and the 77 SMK.  the Hornady supposedly has a profile that is more similar to the 77 SMK, but it is obviously 1gr lighter than the 69 SMK.

i also made two sets of workup loads, which i shot a few weeks prior.  each set was 10 rounds total with each round increasing in 0.1gr increments from 23.6 to 24.6.  i fired these through two different rifles to test the upper limit of the load.  after every shot, i checked for pressure signs.  the pressure testing loads were measured on a hornady auto dispenser.

I have to say you seem to have a good plan and you are being very careful. Especially while you approached and surpassed the listed maximum. I don't disagree with going over a listed load if you work up in very small increments and keep an sharp eye on over pressure signs. You are using a powder in the correct burn speed range. I have a couple of loads that go over listed maximums. Both of these are for bolt guns and not an AR platform.

I was surprised to see with all of my books that there was so little data on that powder. I bought a pound of that powder to try some day. But now that I see so little data on it I am getting eager to start developing loads with some bullets I know work well in my guns. I did find two separate listings for 69gr at 21.0 - 23.8 grains. It does appear that your accuracy is coming together at that 24.4gr load.

With all this said I would like to suggest that compared to some of the other powders listed, the 8208 XBR was one of the more efficient powders but not the most efficient. I would be concerned as you approach and surpass the listed max that you could get occasional pressure spikes. I am only speculating here as I have no experience with this particular powder. It is only a concern I have. For instance if one bullet seats tighter into the case than one that doesn't show signs of over pressure then there is a slight possibility of higher pressures. This is assuming you don't crimp. And if you don't crimp you also run the risk of a bullet jumping farther back into the case while in the magazine during firing that can cause higher pressures. These are corner cases but can become a concern as you are surpassed the recommended maximum. My recommendation is to do a comparison of pressure versus velocity and see if you can find a more efficient powder that meets or exceeds your velocity obtained with the 8028 XBR at a lower pressure. For instance, I noticed H4895 seemed to be a powder that did just this. Not that I am recommending H4895 for your testing, it is just an example as I noticed because H4895 is a powder I use a lot in other applications. The 8208 XBR is listed as 2969fps at 52,900 CUP using 23.8gr. The H4895 is listed as 3069fps at 49,700 CUP. Again, this is just an example for comparison purposes as I would not necessarily recommend H4895 in this application. Also, not trying to tell you what to do, just suggesting you might want to look into another powder that can provide better velocities at lower pressures since you seem to be getting your best accuracy at the highest velocities. A quality firearm in good condition should have no problem with the higher pressures assuming no pressure spikes occur for whatever reason.

Good luck with your load development. You are doing a great job. 

I misspoke earlier. The Hornady 9th does have loads listed for 68gr and 8208 XBR. The max in the book is 24.1gr and it is listed under the 5.56mm NATO section. Hornady also lists the COL at 2.250". According to Hornady, they achieved 2900 fps out of a 20" AR-15.

At 24.4gr, im just a hair over 1% above the maximum.

There are mainly 3 reasons why I chose this powder.

1) it seems to get a lot of hype since it is a short extruded powder
2) it was one of the few powders that was readily available when I got into reloading a few years ago
3) it supposedly works well in 308 Win too

8208 XBR in its current form is relatively new to the market so there isn't a whole lot of info on it.

"in it's current form"?
you mean they changed the formula and kept the name the same?
that doesn't seem to be a great idea to me...

"in it's current form"?
you mean they changed the formula and kept the name the same?
that doesn't seem to be a great idea to me...

Yeah there's a long history behind the name. The short story is there was a military lot of powder that ended up being absolutely loved by bench rest shooters. I think it had a similar name, but this was decades ago. Hodgdon/IMR decided to bring it back, but they changed the formula when they did. When the powder first hit the market, there were a lot of people that were asking if this had anything to do with the old lot.

I may have gotten some parts wrong so forgive me if I made any errors.

Looks great!  and looks like you did this test perfectly.  By my estimation you have found two nodes in your testing.  If you look at 23 and 23.2 you have impact in the same group center.  At 23.4 you have the "scatter node" .  Next you find the groups tightening up again 23.8 is right out of the scatter node and that is why the group hasn't settled yet.  Lastly you have 24, 24.2, 24.4 all landing at a common group center, if you were to shoot all of those loads, at even that much of a spread, they would all land within a little more than half an inch!  that right there tells you what you need to know.

I'd concentrate on the middle charge, 24.2.  Slowly seat the bullet deeper in the case by maybe .003" or .005", make three rounds each depth and shoot three round groups. No need go crazy maybe three to five sets.. You will see it tighten up then open back up again.  Choose the tightest groups seating depth and you are done!  Zero your scope and maybe do a confirmation group of ten rounds to see if they are more or less consistent in impact.  Pau!

OCW will be consistent no matter mixed headstamp brass, however I'd say don't load that hot in regular .223 brass or federal brass.    Was this 69SMK at those charge weights?   I'm around that same charge with my 69TMKs.
 
AMEN for OCW!

Looks great!  and looks like you did this test perfectly.  By my estimation you have found two nodes in your testing.  If you look at 23 and 23.2 you have impact in the same group center.  At 23.4 you have the "scatter node" .  Next you find the groups tightening up again 23.8 is right out of the scatter node and that is why the group hasn't settled yet.  Lastly you have 24, 24.2, 24.4 all landing at a common group center, if you were to shoot all of those loads, at even that much of a spread, they would all land within a little more than half an inch!  that right there tells you what you need to know.

I'd concentrate on the middle charge, 24.2.  Slowly seat the bullet deeper in the case by maybe .003" or .005", make three rounds each depth and shoot three round groups. No need go crazy maybe three to five sets.. You will see it tighten up then open back up again.  Choose the tightest groups seating depth and you are done!  Zero your scope and maybe do a confirmation group of ten rounds to see if they are more or less consistent in impact.  Pau!

OCW will be consistent no matter mixed headstamp brass, however I'd say don't load that hot in regular .223 brass or federal brass.    Was this 69SMK at those charge weights?   I'm around that same charge with my 69TMKs.
 
AMEN for OCW!

Heavies, thanks for the reply!  i'll take your advice and start measuring out my next test load.

Heavies, please correct me if i'm wrong, but the OCW method isn't about the tiniest groups.  it is more about finding a charge weight in which i can have minor variations in temp, brass, primer selection, or charge weights and still be within the "node," right?

if so, then it would make sense why i'd use 24.2gr as a starting point for the final stage of the development because i know that i can be high or low by 0.2gr and still be within the "node" and also still have relatively the same point of impact (therefore no scope adjustments are required).

Heavies, thanks for the reply!  i'll take your advice and start measuring out my next test load.

Heavies, please correct me if i'm wrong, but the OCW method isn't about the tiniest groups.  it is more about finding a charge weight in which i can have minor variations in temp, brass, primer selection, or charge weights and still be within the "node," right?

if so, then it would make sense why i'd use 24.2gr as a starting point for the final stage of the development because i know that i can be high or low by 0.2gr and still be within the "node" and also still have relatively the same point of impact (therefore no scope adjustments are required).

Yes.  You have it down.   OCW finds the point at which powder burn, recoil impulse, barrel harmonics all come together at the moment the bullet exits the barrel.  As the barrel whips in its figure '8' pattern, the bullet leaves the barrel at the apex of the whip where the barrel is at it's end of movement.  The groups will cluster in a circular cloverleaf type pattern.  At the 'scatter node' bullets are leaving at the cross of the figure '8', which is why they are spread far apart. 

However, the tinyest groups possible from the rifle can be achieved as well.  If you were going for benchrest accuracy the load can be further tested by reducing the charge increment even further, after playing with seating depth for the best group possible.  Also, one could use more consistent cases, weigh and sort bullets, turn case neck, ream primer pockets, etc....  Your rifle looks sub MOA already, I think that it will shoot 1/2 MOA after the final tweek.

Yes.  You have it down.   OCW finds the point at which powder burn, recoil impulse, barrel harmonics all come together at the moment the bullet exits the barrel.  As the barrel whips in its figure '8' pattern, the bullet leaves the barrel at the apex of the whip where the barrel is at it's end of movement.  The groups will cluster in a circular cloverleaf type pattern.  At the 'scatter node' bullets are leaving at the cross of the figure '8', which is why they are spread far apart. 

However, the tinyest groups possible from the rifle can be achieved as well.  If you were going for benchrest accuracy the load can be further tested by reducing the charge increment even further, after playing with seating depth for the best group possible.  Also, one could use more consistent cases, weigh and sort bullets, turn case neck, ream primer pockets, etc....  Your rifle looks sub MOA already, I think that it will shoot 1/2 MOA after the final tweek.

thanks for the positive encouragement.

Heavies, i have few more questions for you.  given that i'm somewhat limited by the mag length of an ar15, how much will i actually gain by playing with the seating depth?  currently i'm loading at COL 2.260", which is pretty much max length.

when a manufacturer claims a rifle/barrel to be sub-moa, is that usually sub-moa for a three-, five-, or ten-shot group?  and when the rifle is tested for accuracy, how much time does the shooter wait between shots?  for the OCW testing i did on saturday, i usually waited for my barrel/gas block to come back down to a resting temperature.  this equated to somewhere between 1-2 minutes per shot.  to test temperature, i just did the finger test (aka "yeah that seems about right").  in between my load development shooting, i was plinking with the Ruger American Rimfire as a temporary scratch to my itchy trigger finger.

thanks for the positive encouragement.

Heavies, i have few more questions for you.  given that i'm somewhat limited by the mag length of an ar15, how much will i actually gain by playing with the seating depth?  currently i'm loading at COL 2.260", which is pretty much max length.

when a manufacturer claims a rifle/barrel to be sub-moa, is that usually sub-moa for a three-, five-, or ten-shot group?  and when the rifle is tested for accuracy, how much time does the shooter wait between shots?  for the OCW testing i did on saturday, i usually waited for my barrel/gas block to come back down to a resting temperature.  this equated to somewhere between 1-2 minutes per shot.  to test temperature, i just did the finger test (aka "yeah that seems about right").  in between my load development shooting, i was plinking with the Ruger American Rimfire as a temporary scratch to my itchy trigger finger.

No prob.  Since you started at around max mag length, which is a good thing to do, go deeper into the case and make the OAL shorter.  When you shoot the round robin 3 round groups of the sets, you should see the groups either tighten up then go back out, or perhaps grow at first then shrink.  Either way the best grouping would be the one you want. 

For the sub MOA, the rifle should shoot a given good match ammo into <1" at 100 yards with all shots, save a few fliers that may get in there.

For my uses, I shoot the strings one right after the other.  IE, if I had a set of 5 loads to test I'd shoot lowest to highest first, then let the rifle rest (not too cold but just cooled of some), then highest to lowest, rest again, then lowest to highest.  The uses I have for my target rifles is such that I want that load to perform with gun at temperature.  Plus I want to make sure that the hot chamber doesn't give me any surprise pressure.    I am shooting either F-class or High Power Rifle, so the shots in any given relay are one right after the other with no breaks in between in that relay.  In F-class I'd shoot 18 or 22 rounds as fast as the puller can mark the target in order to stay in the same wind condition.  Only if the wind changes or is difficult, there might be a short break, however there is only 18 minutes or 22 minutes to complete the relay.  Also, one can detect problems with the rifle or free float of the barrel.  A well made rifle, and quality barrel, with that good load might slightly open up groups after heating, it should also come back to normal after cooling.  However, it should not string shots.  Something is either contacting the barrel or the barrel is not properly stress relived if there is vertical or horizontal stringing.