What is an acceptable SD (in your opinion)? [My experiment results]

[alamo5000]

I have had my go to load for my 16" AR15 for quite a while now. That load is 24.3 grains of Varget and a 69 grain SMK.

When I first built the rifle back in 2015 I chased groups for a while but I haven't done it since. My best effort gave me a 10 shot group that could be covered up (all the outside edges) by a dime. A dime is .7 inches so I figure I was right around a .5 to .6 MOA group at the time for a single string of 10 shots. It was repeatable (which I did more than once) but I called it good eventually and moved on.

Fast forward a few years and I build a few other rifles and shoot a few other things a lot more and I bought some new toys including a brand new chronograph (labradar), new dies, new press etc. Eventually I roll back around to that rifle and that load.

I got lazy quite a while back and quit being 'super accurate' on my charge weights... I would just drop them with a powder charge and call it good. It served my purposes just fine to do that because I wasn't chasing bug hole groups or anything like that.

What I did today though was found a few small boxes of ammo that I loaded previously using the lazy man's method and I shot (and recorded) some strings just to see what I was getting velocity wise. Previously I didn't have a good chrono at all. This ammo was sitting for at least two years untouched (same with the gun). Not sure if that makes any difference. I used some basic Lake City brass but it was all the same head stamp.

With the old ammo I recorded 39 consecutive shots in a single string and got an ES of 122 and a SD of 26. This was the ammo made with no annealing and a simple powder drop without individually weighing anything.

After that I used the same brass (the exact same pieces) and did my first ever anneal. This was my experiment. I full length resized with a new die (from the old ammo), but I weighed each charge. Everything else was standard fare.

With the weighed charges (and anneal) my SD went to 14 and my ES 37. It's a big improvement over the previous ammo (using the exact same pieces of LC brass) where I got an ES of 122 and an SD of 26. It's also worth noting that the first attempt had a few shots that might have been misread. I didn't delete anything so the true numbers might be a bit off.

I still have some of the old ammo left so I might re-run this test.

Let me know what you think of my extremely informal testing and maybe something else or some other ideas that I can add in to the mix.

 

[alamo5000]

On a side note I have 200 rounds of the previously produced ammo left. I will do this experiment again in a more controlled way just to confirm my results. I had a few things that I did that I want to do differently the next time. The next go I might do something like 20 shots or something like that and keep everything consistent.

I will try to shoot at a pace that gives more consistent readings and I will delete any obvious outliers that were from chrono errors or whatever and I will do the same precise thing on both strings. The first time I was shooting the string I was actually just playing around with my chronograph and just recorded what I had. I didn't have the idea to compare results until later on.

Anyway I think it still shows a bit of improvement. Either way the first test was a good indicator.

 

[memtb]

Pretty impressive results, though, I wish you hadn’t introduced two (2) variables. I would be very interested to see what annealing alone would have produced for spreads! memtb

 

[huntnh]

If I’m under 10 Sd I’m super happy load I’m shooting now is around 15 but constantly producing groups under a half inch.

 

[J McGriddle]

To me, what determines if a SD is acceptable depends on the size of the target and the distance.

 

[OneMoreNoMore]

If your ammo has been sitting for 2yrs you may want to seat the bullets another .005-.010 deeper to break any cold weld. Should help with more consistent bullet release.

 

[Dthomas3523]

If you’re not just running 3-5 rounds over a chrono and actually looking at long term results, 10sd is doing very, very well.

Ignore all the “3sd and 12es” posts.

 

[OneMoreNoMore]

What he said ^.
I’ve been hooked on Eric Cortina and F-Class John’s YouTube channel and watching their reloading steps. F-Class John is as detailed as I’ve ever seen anyone and his ES on the shot marker at distance was 29 for 20 shots IIRC. With that being said his vertical is crazy small.

 

[alamo5000]

Thanks everyone!

I didn't want to do more than one variable at a time either but this whole experiment was literally off the cuff. I was in the back yard just shooting to be shooting and like I said, I did a 39 shot string that was recorded just because I had a new chrono and wanted to see what it would do. It wasn't until I was almost done that it dawned on me that it could be valuable information in there so I decided to compare kind of after the fact despite inconsistencies in how I treated everything.

I actually think I had a few more variables in the mix that I didn't think about at first. Hence I want to re-run the test without touching anything on the old ammo and try to do it more 'heads up'. Basically I want to do a deliberate test where I can remove as much variation as possible within reason.

I can't recall exactly but I am pretty sure these last two boxes were some of the hand weighed stuff (I think) but there is no way to know for sure without possibly pulling a bullet or whatever, which I might do just to know for sure. I know I used to keep one or two boxes of 'the good stuff' (ammo that I took my time on and weighed out each charge) on hand as my go to stash. If one, or both of these boxes are like that it will be great. If not I can just load some more and come up with a different type of experiment to work with next time.

I didn't have an even number of shots on the second round as I did on the first try. Between lost brass and pieces I got mixed up and wasn't sure of I had less total shots on the second round which I will try to correct on round two. I will try to do it again when I can and see if I can shrink the numbers even more and either validate (or not) this first test.

One thing I did notice on my target (325 yards) was in my first group the vertical stringing was a lot more. On the second round even though I wasn't taking my time AT ALL (I was focused on getting the numbers not groups) the group was quite a bit better and had this nice round pattern whereas on the first I was hitting the target obviously but there was a much bigger deviation.

 

[alamo5000]

If you’re not just running 3-5 rounds over a chrono and actually looking at long term results, 10sd is doing very, very well.

Ignore all the “3sd and 12es” posts.

I definitely didn't just shoot 3-5 rounds. LOL

In my first string I had 39 recorded shots.

In my next test (maybe tomorrow) I will do like 20 and 20 to see what I am getting.

Also my optic on this rifle is far from anything to do precision work at long ranges. It's a 1-4x so after a certain point it's just kind of 'getting on target'. Eventually I will replace that optic I think because I am converting everything to MIL going forward. It's not a priority right now but eventually I would like to do it.

 

[alamo5000]

I have been thinking on it and I might try something in addition to this. Not sure if I am going to do it on this test or a new test...

What I might do on this (or maybe another) test is to number my cases with a sharpie marker #1 through #20 and load them in the mag so that they are in order. Then I will try basically the same test using the same brass etc and see if I can 'sort my brass' using a once fired method.

I didn't have the ability to do that before but the new chrono records and numbers shots and all that so now it could be possible. It doesn't have to be done with old ammo. I can do that one with newly loaded ammo. But if I can sort the brass by velocity achieved I wonder if I can get single digit SD's that way....it would be an interesting test I think.

 

[Pritch]

One thing that springs to mind instead of numbering rounds (which will give you the same results as what i'm going to tell you)

get fired brass with the primer still in it get the electronic scales out and weigh a piece of brass then using a syringe fill the brass up with water to the brim, then from there record the weight difference with and without water (granted things are going to need to be trimmed to the same length here)

batch the brass from there and see what happens

This process will give u the volume inside the case

Only reason i say to try this way it should save u on burning components

Hope that helps a little

(try changing seating depths see where the sweet spot is)
(dont let your rounds cook in the chamber it increase powder temp)

 

[Dthomas3523]

Just buy lapua brass, use a mandrel, and weigh powder to a kernel. That will get you well into acceptable range.

 

[Steel head]

In an AR?
For ammo used in realistic distances I just get the bullet to an acceptable speed and play with jump a bit if needed.
My favorite AR load (69smk/w748) has a maybe 20 SD but shoots great.

 

[Lionsbreath]

Is it even possible to get basement numbers on a .223, due to the size of powder charge? I
always chrono 10 rds and I’m usually around 10 SD/ upper 20’s ES, using Lapua, 450’s, mandrel, bushing dies.. I’m definitely not worried about, as this is a 600 yd and in, fun gun..

 

[BLKWLFK9]

ES's and SD's tell u 2 different stories. As long as I am comfortable with the ES, the SD will be fine. Now, if I have 2 loads with the same ES but different SDs, I'll go with the lower one but that being said, either would be fine because the ES is exceptable. For PRS, the highest ES I will roll with is about 25-30. Hunting, a little more. If I were shooting fclass or something, I'd try to get a sub 12 fps ES.

 

[Lionsbreath]

10-4, yeah that’s good Info.. My Creedmor on the other hand is hammering the 123 Scenars with H4350.. Getting her tuned up for a Pactolus match

 

[Dthomas3523]

Is it even possible to get basement numbers on a .223, due to the size of powder charge? I
always chrono 10 rds and I’m usually around 10 SD/ upper 20’s ES, using Lapua, 450’s, mandrel, bushing dies.. I’m definitely not worried about, as this is a 600 yd and in, fun gun..

Upper 20 ES will work plenty past 600.

Anyone claiming they get under 20 ES with large samples of any ammo, not just .223, would be in the class of the most elite ammo on the planet.

 

[alamo5000]

Upper 20 ES will work plenty past 600.

Anyone claiming they get under 20 ES with large samples of any ammo, not just .223, would be in the class of the most elite ammo on the planet.

I'm going to find out soon enough where I am at. I shot a 20 shot control and will shoot 20 more soon to validate my results one way or the other.

As far as working goes I can hammer steel at 800 yards all day long with the ammo I have already.

My second set came back at 24 SD but I know for sure I can hit 800 yards with a 16 inch AR15.

 

[axarob44]

Upper 20 ES will work plenty past 600.

Anyone claiming they get under 20 ES with large samples of any ammo, not just .223, would be in the class of the most elite ammo on the planet.

Some of the numbers I see posted here really make me think "there ain't no way you're getting that low an SD or ES with anything but 3-5 rounds. Also some of the velocities that get posted are BS too especially some of the .223 5.56 numbers in an AR. Are you getting your powder the same place Jack bought his beans? Go look in the .223 for AR section, you will be amazed.

 

[Molon]

Hand-loads fired from a 20" semi-automatic Colt AR-15 A2.

extreme spread = 17 FPS

standard deviation = 4 FPS

....

 

[alamo5000]

Hand-loads fired from a 20" semi-automatic Colt AR-15 A2.

....

Very nice! BTW nice to see you here as well!

Do you mind sharing what type of brass you are using?

I haven't bought any nice brass yet but I might buy some just because I can and I am a bit curious about it.

 

[blaserman33]

I would like to see you test the difference between firing the old rounds as is vs some that you seat .005” deeper just to break the cold weld from them sitting. That would show how much effect on accuracy there is with ammo that has sat for a while.

 

[alamo5000]

Some of the numbers I see posted here really make me think "there ain't no way you're getting that low an SD or ES with anything but 3-5 rounds. Also some of the velocities that get posted are BS too especially some of the .223 5.56 numbers in an AR. Are you getting your powder the same place Jack bought his beans? Go look in the .223 for AR section, you will be amazed.

So you are telling me that people on the internet embellish their accomplishments?

O.M.G!

And for a minute there I was thinking I was the only person in America without a quarter minute gun. LOL!

(I am just being a smartass making a joke. It's all good)

 

[alamo5000]

I would like to see you test the difference between firing the old rounds as is vs some that you seat .005” deeper just to break the cold weld from them sitting. That would show how much effect on accuracy there is with ammo that has sat for a while.

It might take me a few days to get all my stuff out and go shoot but I do have something like 140 rounds left that I can test.

On that though I have a hypothesis that it won't be a big difference. All of my ammo is stored inside a controlled environment.

Of course I can test it no problem but I don't think it will have a big difference.

 

[Molon]

Very nice! BTW nice to see you here as well!

Do you mind sharing what type of brass you are using?

I haven't bought any nice brass yet but I might buy some just because I can and I am a bit curious about it.

Lapua Match or virgin Lake City.

....

 

[blaserman33]

It might take me a few days to get all my stuff out and go shoot but I do have something like 140 rounds left that I can test.

On that though I have a hypothesis that it won't be a big difference. All of my ammo is stored inside a controlled environment.

Of course I can test it no problem but I don't think it will have a big difference.

It’s not really about how it’s stored, but I’ve heard that over long periods of time the case and bullet will become somewhat “welded” together just because of the pressure of the neck tension over a long period of time, therefore you have very inconsistent bullet release.

 

[Jayhawkhuntclub]

If I get sd in the teens with 223 ammo, I feel like I've accomplished something. By comparison, something like a 6BR or a 6.5 CM, I expect them to be in the single digits. In my experience, it's much easier to get single digits wit the BR or CM than it is to get below 20 with the 223. Ultimately, if you're getting the groups you want at the distance you want, your sd is irrelevant.

 

[OneMoreNoMore]

I’ve read that it is harder to get low es sd with heavy bullets in 223. I’ve had very limited experience with heavies in smaller calibers so I can’t confirm.

 

[alamo5000]

I’ve read that it is harder to get low es sd with heavy bullets in 223. I’ve had very limited experience with heavies in smaller calibers so I can’t confirm.

Molon posted above the printout from one of his sessions using 77 grain bullets.

He got a 10 shot group with an SD of 4.

That said I've never chased an SD before. Never had a chronograph that made it as easy as the one I have now to do so.

 

[whatsupdoc]

Low ES and SD in 223 are way harder to achieve than say a 6.5 Creed.

Here are some gas gun numbers.

Factory Ammo

Federal FC262 77 OTM (If I had only bought like 5K of these)

Total number of shots 5

Stats - Average 2868.86 fps
Stats - Highest 2884.96 fps
Stats - Lowest 2860.02 fps
Stats - Ext. Spread 24.94 fps
Stats - Std. Dev 10.13 fps

Federal FC262 77 OTM (Shot second string to confirm)

Total number of shots 5

Stats - Average 2873.45 fps
Stats - Highest 2882.92 fps
Stats - Lowest 2863.78 fps
Stats - Ext. Spread 19.14 fps
Stats - Std. Dev 7.35 fps
--------------------------------------------------

Best Handload 77SMK, 8208XBR

Total number of shots 15

Stats - Average 2815.27 fps
Stats - Highest 2829.46 fps
Stats - Lowest 2803.38 fps
Stats - Ext. Spread 26.08 fps
Stats - Std. Dev 9.14 fps

Total number of shots 10

Stats - Average 2842.79 fps
Stats - Highest 2855.87 fps
Stats - Lowest 2831.09 fps
Stats - Ext. Spread 24.78 fps
Stats - Std. Dev 7.74 fps
--------------------------------------------------


Funny thing is a few days ago I tested some N133 powder with 69 SMK in a bolt 223
Lowest 223 numbers I have ever seen.

Total number of shots 5

Stats - Average 2986.47 fps
Stats - Highest 2990.88 fps
Stats - Lowest 2984.51 fps
Stats - Ext. Spread 6.37 fps
Stats - Std. Dev 2.58 fps

Total number of shots 5

Stats - Average 2926.56 fps
Stats - Highest 2931.2 fps
Stats - Lowest 2922.69 fps
Stats - Ext. Spread 8.51 fps
Stats - Std. Dev 3.59 fps

 

[alamo5000]

I finally redid the test. Been super busy.

Recapping:
I got 24.7 SD with a 20 shot control group.

Results of annealing:
I used the exact same brass with the only difference between the two being annealing.
I got a good recorded 18 shot group and my SD went down to 17.

If I had discounted my first two shots (cold bore & cold bore +1) my SD would go down to 13.4 across 17 shots.

I had two shots that I felt were outliers and quite possibly bad reads so I deleted those two (one was the cold bore). Still 18 shots to 20 shots is a fair comparison and yielded a 7.7 gain (or 11 depending how you look at it) out of the SD with the only difference being annealing.

One thing I did notice... I was shooting at a 300 yard plate and today was windy as hell. I really wasn't even shooting for groups or trying to see how close I could get anything. I just basically did a fairly steady string of fire and my group downrange was substantially better than before. I was pleased.

I definitely feel like there is more to be gained. The test above was merely a test for my own benefit.

 

[alamo5000]

Funny thing is a few days ago I tested some N133 powder with 69 SMK in a bolt 223
Lowest 223 numbers I have ever seen.

Total number of shots 5

Stats - Average 2986.47 fps
Stats - Highest 2990.88 fps
Stats - Lowest 2984.51 fps
Stats - Ext. Spread 6.37 fps
Stats - Std. Dev 2.58 fps

Total number of shots 5

Stats - Average 2926.56 fps
Stats - Highest 2931.2 fps
Stats - Lowest 2922.69 fps
Stats - Ext. Spread 8.51 fps
Stats - Std. Dev 3.59 fps

I have been we eager to try several VV powders but it ain't happening until the crazy train stops and things get on the shelves. Usually I try different powders until I find something I like then I try to buy as much of it as I can.