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Acceptable standard deviation for .223


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I have been reloading .223 for general range use, not precision shooting. I use a Dillon 1050.

I do bulk reloading of a couple of thousands at a time. Usually 55 grain FMJ Hornady on LC brass using H-335 or CFE 223. I usually get around 3000 FPS out of a 16 inch barrel.

This last week I did some chrono testing.

I did several groups of ten based upon the brass that was used. Everything else was the same (powder, load, primer bulltet OAL etc).

For the strings of ten I was running there was somewhere between 24-28 FPS standard deviation. One of them was 32 FPS.

Does anybody have any good thoughts on what would be an acceptable standard deviation? I remember a few years ago testing some factory ammo and getting a 40 FPS SD.

I know for precision shooting single digits SDs are desired but I am looking for range use bulk reloading I am wondering if my 25-30 FPS SD or so is considered acceptable.

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Depends on what you are doing. If shooting 3 gun matches, you are in great shape. Most of the shooting will be less than 100 yards.

For longer ranges, I up the ante using 77 gr SMK or Nosler CC. Using IMR 8208xbr loaded on a Dillon 550 I often get spreads of 30 to 45 fps. Putting them on paper shows to me that they are more than accurate enough for my type of shooting.

Bill

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Here are my thoughts....

Unless you are sorting brass by weight or volume.... neck turning.... neck sizing etc.... don't get wrapped around the axle over spreads up to and a bit beyond 50 fps. Actually, 50fps is pretty good. We're talking extreme spreads here in a sample of 10 or so rounds. The temp of the barrel and the rate of fire will have an effect this measurement. The pace of your shot string... the temperature... the volume of powder in the case and the position of the powder... lots of variables.

Your loading bulk in a progressive machine and dispensing powder by volume. Your doing very well to get those spreads considering all the balls in the air that are out of your control.

If you don't feel confident that you are producing pretty good ammo... try this experiment. Load up 20 or so rounds... and measure the powder by weight. Intentionally vary the load by a few 10ths every other round or so... of course be safe... don't conduct this experiment on the edge of max charge. Now on a nice day... go the range and set up a target at 300 yards or so. Set up you chrono and fire your test rounds. Go down range and police up your target. You will feel pretty confident then.

Incidentally, I feel like I've hit on a pretty good load when I can get SD's in the 10-11 or less range. That however doesn't mean that you have an accurate load for that rifle.... not by a long shot. You need to fire the loads AT DISTANCE in good conditions. Look up latter testing. It's a process that will teach you what you need to know in order to produce the best ammunition for that particular rifle. Targets don't lie.

Ill edit this in... When you begin to get serious about producing accurate rifle ammunition, you have to realize that it's a whole new game with regard to handloading. I would bet that at least 90% of all handloaders of rifle ammunition either never produce ammunition any better than off the shelf bulk stuff or get real lucky and fall into a load that surprises them. The trick is to understand that you have to build the ammo for the rifle.... and if your lucky, it will work well for another rifle too.

The experiment I suggested was intended to demonstrate how little some of the elements (like powder charge or SD's) have any real effect on accuracy up to about 300-400 yards. They don't matter much. Finding the node of your rifle will be FAR ,FAR AND AWAY more valuable to increasing your accuracy. This is the secret that will allow you to produce the most accurate ammo for your rifle and will show you the potential accuracy of the rifle itself. Don't fall into the 100 yard groups for accuracy mindset or the magic number on the chrono crowd.

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Here are my thoughts....

Unless you are sorting brass by weight or volume.... neck turning.... neck sizing etc.... don't get wrapped around the axle over spreads up to and a bit beyond 50 fps. Actually, 50fps is pretty good. We're talking extreme spreads here in a sample of 10 or so rounds. The temp of the barrel and the rate of fire will have an effect this measurement. The pace of your shot string... the temperature... the volume of powder in the case and the position of the powder... lots of variables.

Your loading bulk in a progressive machine and dispensing powder by volume. Your doing very well to get those spreads considering all the balls in the air that are out of your control.

If you don't feel confident that you are producing pretty good ammo... try this experiment. Load up 20 or so rounds... and measure the powder by weight. Intentionally vary the load by a few 10ths every other round or so... of course be safe... don't conduct this experiment on the edge of max charge. Now on a nice day... go the range and set up a target at 300 yards or so. Set up you chrono and fire your test rounds. Go down range and police up your target. You will feel pretty confident then.

Incidentally, I feel like I've hit on a pretty good load when I can get SD's in the 10-11 or less range. That however doesn't mean that you have an accurate load for that rifle.... not by a long shot. You need to fire the loads AT DISTANCE in good conditions. Look up latter testing. It's a process that will teach you what you need to know in order to produce the best ammunition for that particular rifle. Targets don't lie.

Ill edit this in... When you begin to get serious about producing accurate rifle ammunition, you have to realize that it's a whole new game with regard to handloading. I would bet that at least 90% of all handloaders of rifle ammunition either never produce ammunition any better than off the shelf bulk stuff or get real lucky and fall into a load that surprises them. The trick is to understand that you have to build the ammo for the rifle.... and if your lucky, it will work well for another rifle too.

The experiment I suggested was intended to demonstrate how little some of the elements (like powder charge or SD's) have any real effect on accuracy up to about 300-400 yards. They don't matter much. Finding the node of your rifle will be FAR ,FAR AND AWAY more valuable to increasing your accuracy. This is the secret that will allow you to produce the most accurate ammo for your rifle and will show you the potential accuracy of the rifle itself. Don't fall into the 100 yard groups for accuracy mindset or the magic number on the chrono crowd.

Good input.

The charge I was using is my sweetest load for general range accuracy. I normally can get 1-1.5 inch groups with my non precision shooting ARs. The one AR I have that is a more precision built I can get a little less than one inch.

Since I am doing it in bulk I am not bothering with separating the projectiles or cases out by weight. I know if I did that the accuracy would improve.

I trim on a Giraud and of course have the Dillon powder dispenser, which has some variation on it.

I also only separate brass by headstamp and not year.

I am capable of reloading percision on my single stage press and I do it for my .308 loads but since I shoot so much .223 I just do it in bulk.

I am trying to get a handle around how important the velocity varaition is. I would expect it to be directly tied to accuracy but if it is then I haven't seen it in my groups. I have been shooting these loads for awhile and only last week did a chrono on it.

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From the sounds of it, you are producing really good ammo. If it meets your needs.... and it sounds like it does... great. This whole handloading process and pursuit of accuracy is half the fun of firearms and shooting for me. It can be a real challenge to squeeze a little more accuracy from a firearm and improve it's performance.

I'll stick my neck out and suggest that if you were to experiment with a different bullet or three your accuracy will improve. Once you really drink he Kool aid and start driving for higher levels of consistency, the FMJ will just hold you back.... provided you have a rifle capable of sub MOA accuracy. Bullets matter, and the Hornady FMJ.... while a good bullet... with excellent performance within its design and purpose... isn't a target bullet... or a particularly consistent or accurate bullet. I use them for blasting.

I like to do my accuracy testing at 200 yards at the minimum. 100 yds is ok for chrono work.... not accuracy. It takes a little distance for a bullet to settle down. It is not uncommon to fire a 1 moa group at 100 yds and then fire a sub moa group at 200 using the same load.... consistently.

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