SD/ES Help!...pleaseee

[Tha Gunson]

I am having trouble lowering my SD/ES with my match AR. Right now it's around 11 and 25fps respectively, and I don't know what else I can do to get it down. I've also noticed during load development it's often the case that the load with the lowest SD isn't very accurate and vice versa. The gun shoots anywhere from .3-1.25 MOA. I've realized too that a lot of times in a 5 shot string if I could eliminate 1 of those velocities my SD/ES would be cut at least in half. I have no idea how but recently 23.8gr of varget gave me 3inches of vertical at 100yds over 5 shots with a 9.2fps SD?? Then 23.9gr gave me 0" of vertical and .5" of horizontal with an SD of 11.3fps. This is what bothers me and why I feel like I could easily still improve. All testing is out of a Green Mountain 20" drop in barrel with a Labradar at 100yds. How I reload:

-LC 08 brass, once fired, stainless pin tumbled, resized to max headspace for my rifle with Hornady dies. Results in .003" neck tension.
-Trim to 1.750", chamfer, debur with Frankford Arsenal rotary trimmer
-Uniform primer pockets to .020" and debur flash hole
-Prime with CCI450
-Charge cases with Varget to +/-.02gr accuracy with Gempro250
-Weigh 77gr smks to +/-.04gr and seat with Hornady seater
-Finished rounds are checked with comparator for base to ogive within +/-.0005"

I'm switching to a Redding body die and lee collet neck sizer, just waiting for them to get here. I'm aware of a lot of other things guys do when reloading and theories behind them, just don't want to spend the money until I'm convinced it will help. Data and/or anecdotes with your suggestions are most appreciated.

 

[Terry]

There is a long list of things to try. Let's start with the cheap ones. Try different primers and bullets. Both can change it.

 

[hogpatrol]

What he said ^^^ First, I'd ditch the magnum primers. On top of that, what is your expectations of a GM barrel?

 

[Tha Gunson]

I switched to the magnum primers only
because I saw a video where a guy got more consistent velocities (albeit a different cartridge) with them and I found that to be the case too. I improved a few other reloading techniques at the same time I switched primers so I can't be 100% certain. I was under the impression 77gr smks have a reputation as the best heavy bullet for a mag fed AR ...I would be very pleased with .5 moa accuracy and have even shot numerous groups under that but it's pointless when the SDs approach 15-20 (for this rifles purpose).Then I've shot many single digit SD groups that aren't even under an inch. It just doesn't make sense.

 

[sparker]

Not to step on toes but, this is the first thing you need to do:
Lay down with someone's AR that shoots extremely well. If you shoot it well, then you have a gun problem. If not, you have a gun handling problem. This fork in the road is the most important one to clear up.

Scott Parker
Single Kernel Scales

 

[dstoenner]

Don't confuse low sd/es with absolute accuracy. There are a lot of things in play that effect accuracy. One of those being barrel harmonics. That is probably the reason you got that one large vertical even though the es was low.

If you use a ballistics program you can plug in your extreme spreads to see what that alone would do for accuracy at 100 yards. You will find it might be contributing.1 inch or so.

Case and bullet runout can be adding more to the group size than all the rest combined. If you haven't measured that you don't have a complete picture.

I also agree to loose the mag primers. I have found personally in my match AR is 8208 powder in LC cases with BR4 primers to be the best in 52 to 55 gn bullets. I also only use Berger target bullts if i am looking for best accuracy

David

 

[Tha Gunson]

Scott, I've seriously considered that but with my 6.5cdm bolt gun my data is way more consistent and groups way tighter. It does have a much better scope and lighter trigger though. Not a lot of precision ARs up and down the ranges I shoot at.

 

[ballisticdaddy]

I switched to the magnum primers only
because I saw a video where a guy got more consistent velocities (albeit a different cartridge) with them and I found that to be the case too. I improved a few other reloading techniques at the same time I switched primers so I can't be 100% certain. I was under the impression 77gr smks have a reputation as the best heavy bullet for a mag fed AR ...I would be very pleased with .5 moa accuracy and have even shot numerous groups under that but it's pointless when the SDs approach 15-20 (for this rifles purpose).Then I've shot many single digit SD groups that aren't even under an inch. It just doesn't make sense.

I would recommend trying the Federal AR Match primers as I have had good success with them. I shoot ladder drill using 5 rounds in each charge weight and compare both the target with the chronograph numbers. My lowest extreme spreads are usually not my tightest groups, let the target tell you which charge weight to utilize and not the chronograph. Also are you shooting from a bipod and rear bag?

 

[CharlieNC]

Based on 5 shots the SD's are not different.

Confirm your charge weights are correct by double weighing them.
For the errant poi and velocity, segregate that brass. Compare water capacity and dimensions.

Assuming you can replicate the verticle spread differences on the two charges, this suggests you are not in a node. Did you evaluate a range of charges using ladder or ocw?

 

[Rsadams]

Let the paper tell the story... Don't get hung up on this... Some of my good groups sometimes have not so great sd and es but the one hole in the paper says it's good.. then a crap group will have a 9 sd and low es. I used to try end get the numbers down but when you pull one shot and the other 4 are .008 bigger than the diameter of the bullet I don't care what the es and sd say.. just happened again a few days ago.. IAM sticking with that load for now lol... The one with great sd and es was one inch vs the other of .318 if I remember correctly with the worse numbers...

In a perfect world we would love to have great everything.. but the group is what matters..

 

[Clancy]

Gas guns are tricky. It's why I don't shoot them.

Put the chronograph away for a little while, go read "long range load development at 100 yards,"
Shoot your charge weights, and follow the instructions.

 

[eric n]

Getting low ES/SD is tough in a .223.
SD of 8 and mid teens for ES with 20rds is about as good as I can do. As a reference, I can get other calibers into single digits.
You say you can remove 1 shot out of your string and drop your ES in half? I would think you have a glich somewhere in your brass prep or reloading technique.
As others have stated... ES/SD isn't the deciding factor on groups size. Let the target tell you. I had a load that had an ES of 44 that would hold great vertical at 600 and inversely a load that shot like crap with a 14 ES.

 

[Tha Gunson]

I really appreciate the input from everyone. 6.5 guys load development videos say their lowest SD is always also the most accurate so I thought that's what I should be getting lol (I'm new still and I guess it's a different platform/caliber). If I superimpose all the groups I've shot with this one load it's about 2/3 MOA and I'm just gonna go with it, I'm tired of testing!

 

[Clancy]

65guys are pretty sharp, but I tend to take an average of several good opinions.

One last piece of advice. Just about everything but paper lies from time to time. If you can shoot a load at 600 with a temp stable powder that's good 1/10th grain minimum on either side, load a lot of it and enjoy shooting it.

 

[LCazador]

I really appreciate the input from everyone. 6.5 guys load development videos say their lowest SD is always also the most accurate so I thought that's what I should be getting lol (I'm new still and I guess it's a different platform/caliber). If I superimpose all the groups I've shot with this one load it's about 2/3 MOA and I'm just gonna go with it, I'm tired of testing!

What works for other rifles may not work for yours. Even in rifles with identical chambers(cut with same reamer) I still can't get the same exact load to shoot the same. Frankly I don't think you have found the right node. You may have to change powder, as I have found that to be case in the 50 plus years that I have been reloading. Sometimes just a change in lots of powder can make a change. Use match primers and maybe even brass.

 

[Ned Ludd]

^^^ eric n has the right idea. I've loaded .223 Rem for use in F-TR matches for years and I typically see ES values in the 15-25 fps range. That amount of velocity variance is unlikely to be causing major precision issues (vertical) out to 600 yd. Using the exact same approach and equipment, I can routinely load .308 rounds in the 8-12 fps ES range, or just over half what I see with the .223. The smaller case means that many of the normal variances you have to deal with in the reloading process have almost twice the effect on velocity as they do in a .308 case. Your ES/SD values aren't at all bad for that small case.

As far as the inconsistency in precision goes, you could certainly go back and make certain your charge weight is optimal for your barrel length in terms of harmonics/grouping and revisit seating depth to tighten up the groups further, if necessary. It might be well worth your time to do that using the absolute tightest group(s) as the readout, and [temporarily] forget about ES/SD values. Also, it's much harder to shoot with the same precision out of an AR than a bolt gun. All that BCG metal weight moving around, as well as the ergonomics of the rifle may not be quite as amenable to consistency. If you haven't already, you might try shutting off the gas system (if possible) and single feed rounds while doing your load development, which will take the BGC movement out of the equation and see if your groups tighten up.

 

[Tha Gunson]

^^^ eric n has the right idea. I've loaded .223 Rem for use in F-TR matches for years and I typically see ES values in the 15-25 fps range. That amount of velocity variance is unlikely to be causing major precision issues (vertical) out to 600 yd. Using the exact same approach and equipment, I can routinely load .308 rounds in the 8-12 fps ES range, or just over half what I see with the .223. The smaller case means that many of the normal variances you have to deal with in the reloading process have almost twice the effect on velocity as they do in a .308 case. Your ES/SD values aren't at all bad for that small case.

As far as the inconsistency in precision goes, you could certainly go back and make certain your charge weight is optimal for your barrel length in terms of harmonics/grouping and revisit seating depth to tighten up the groups further, if necessary. It might be well worth your time to do that using the absolute tightest group(s) as the readout, and [temporarily] forget about ES/SD values. Also, it's much harder to shoot with the same precision out of an AR than a bolt gun. All that BCG metal weight moving around, as well as the ergonomics of the rifle may not be quite as amenable to consistency. If you haven't already, you might try shutting off the gas system (if possible) and single feed rounds while doing your load development, which will take the BGC movement out of the equation and see if your groups tighten up.

I agree with both of you which is actually why I created the post. I should have never mentioned the 3" inch group because that was such a rarity. That rifle will shoot anything off the shelf into at least 1.5 moa. If my numbers are about the best I can get then I'm not too worried. But the fact I usually have an outlier or two that really skews the string makes me think it's a reloading issue. I didn't anneal those once fired cases and think maybe it could be neck related? The other day I shot 4 rounds within a 12fps ES and then a 5th round that was 30fps slower. How does that happen??? It happens too often to be a powder weighing error. That's roughly .3-.4 grains off

 

[Tha Gunson]

What works for other rifles may not work for yours. Even in rifles with identical chambers(cut with same reamer) I still can't get the same exact load to shoot the same. Frankly I don't think you have found the right node. You may have to change powder, as I have found that to be case in the 50 plus years that I have been reloading. Sometimes just a change in lots of powder can make a change. Use match primers and maybe even brass.

I was under the impression I was using the best/most consistent brass, primer, powder, and bullet available. I'm open to any suggestions. I've tried H4895 but got similar "conflicting" results

 

[Highpower-FClass]

I'll add a +1 to eric n and Greg's statements. My life became a lot more harmonious and less stressful when I gave up the expectation of getting the same ES/SD results in 223 that I get for 308. Now I use my chronograph to get average velocities, I still look to see what the SD/ES is but it has no bearing on me selecting a load.

Your reloading process looks sound. In terms of 'most consistent brass, primer, powder and bullet available' you are using good components. Is Lapua brass more consistent than LC? Probably but not sure if it would make a practical difference in a gas gun.

Different projectiles, primers, seating depths, charge weights, neck tension and the other myriad of regular variables could make a difference for your accuracy but that's just the regular 'load development puzzle'

The other day I shot 4 rounds within a 12fps ES and then a 5th round that was 30fps slower. How does that happen???

I see stuff like this too, when shooting 223. Perhaps 30fps difference is an outlier but pretty wild swings - yes.

 

[Rsadams]

I was under the impression I was using the best/most consistent brass, primer, powder, and bullet available. I'm open to any suggestions. I've tried H4895 but got similar "conflicting" results

Even if you use a load that's great in one rifle it may shoot like crap in another... You have to work a load for each rifle.. even when useing the best components made... You can buy two rifles at one time both the same and work up a load for one that shoots lights out but not so great in the other..