Help! Horrible StdDev / Accuracy

Flashpoint

Flashpoint

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I've been reloading for a few years but only sporadically, both rifle and pistol. Like many things, I don't spend enough time at it to get good at it. My loads are always pretty inconsistent, sometimes wildly so, at least compared to factory ammo.

Labor day I was at my range taking my first shots with my new Ruger American in 300blk. I had a few Remington subs and some of my own I had loaded with coated 220gr over 7 to 7.8gr in .2gr increments, five of each. My StdDev=22fps, Spread=50fps approximately for 5 shot groups while the factory loads were 1/10 of that.

I weigh every charge using an inexpensive digital scale. It could be the scale but I just think there might be more going on, like inconsistent neck tension or crimp, etc.

I suspect the scale because I notice the tare value wavering .1-.2gr sometimes before I set the powder cup back on it but it always returns to zero. Would an inaccuracy of .1-2gr cause that much deviation?

Anyone have any suggestions as to the best place to start?
 
You've tried one powder, with one bullet. I think I would pick a FMJ bullet that is known to be accurate, and start there. JMHO.

The accuracy issue may or may not be related to the velocity variations. I don't think a standard deviation of 22fps is all that bad, and may not be the cause of accuracy problems inside of 100 yards.

Sometimes, using lead, coated, or even soft point bullets in an autoloader, the bullet nose may be dented or deformed during chambering and can cause accuracy issues.
 
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Powder used?
(I'm guessing H110/296 or Lil gun)
Barrel length?
Muzzle device installed?

Post Pic of typical primer After firing please.

Flaring (belling) case before seating bullet?
Crimping or just removing bell?
 
300Blk, factory brass or made from .223/5.56? If made, all same headstamp? Annealed? These two are oft blamed for inconsistent handloads with formed brass.
 
Asking for a solution to a reloading problem online is like asking webmd to diagnose a health issue. Too many things it could be, too many unknowns.
That said, I don't work for webmd and I am drinking a few Mirrer Rites right now, but from what you've said I'd point the blame directly here...

Flashpoint said:
an inexpensive digital scale
Click to expand...

Those are know to be wildly inaccurate.
Do you know somebody local with reloading experience that could come over and watch while you reload?
If you want I have a good set of scale weights I could mail you so you could check your scale. You can mail them back when you're done.
 
Part II:
The reason I say I blame the scale is you say you weigh every charge.
If you were using a [good] thrower and had it set (even if using a scale that's off) you shouldn't have that much variance load-to-load.
The scale is probably not giving you accurate readings load-to-load.
 
My StdDev=22fps, Spread=50fps approximately for 5 shot groups
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That's just how it looks on paper. How does it look on target? You're not going to make precision ammo with coated boolits that get all jacked up during feeding no matter how carefully you reload them. If you want little cloverleaf groups you should be using a different projectile. And a balance scale. IMO YMMV, etc etc.
 
Digital scales don't get much love from most reloaders, but my balance beam scale stays on the shelf. I have a set of check weights that I use occasionally to verify the operation of my digital scales. They do have limitations (so do balance beams) but I understand that and have procedures to work around those limitations.

Having said that, it does concern me that the OP stated:
I suspect the scale because I notice the tare value wavering .1-.2gr sometimes before I set the powder cup back on it but it always returns to zero. Would an inaccuracy of .1-2gr cause that much deviation?
Click to expand...

One of the limitations of most digital scales is how they operate during trickling operations. The firmware in most scales are not designed for trickling type operation. They are made to weigh a given sample, and settle the reading at some point. Once they have settled, you can add a slight amount to the pan and the scale may not immediately display the change. I work around this by touching the pan after I trickle a small amount, to force the scale to re-settle. Since I acquired my Chargemaster, I don't manually trickle anymore.

Can 0.1 or 0.2gn can make that much variance? If the max charge is 7.8gn, it possibly could make 20fps standard deviation. But I think there are too many other unknowns to know for sure.
 
Thanks for all the advice. I'm looking for a new scale first cause I know I need one, after that I'll start looking at other things. BTW the brass I'm using is all from factory Remington rounds or possibly some from Defender "factory reloads". Have not seen any overpressure signs and don't expect to since I'm loading only subs. Some of my brass I expect I've loaded up to 4 times.
 
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Whew, I read horrible std and I was about to move this to the basement
 
neck tension will give you a wide spread before charge weight variation will.

My system will throw 0.02 grains above or on target everytime. However it did cost $850
 
Just sprung for this, seems like a good price considering what it's selling for other places. The reviews at Brownell's aren't that great but on larger sites like Midway they are quite positive.

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Djstorm100 said:
neck tension will give you a wide spread before charge weight variation will.

My system will throw 0.02 grains above or on target everytime. However it did cost $850
Click to expand...

I'm using a Lee FCD, may be crimping too much, I'm not really sure what the sweet spot is.

Anyone know a good way to bell these case mouths for coated bullets?
 
Djstorm100 said:
I've never crimped rounds for my bolt or AR's.
Click to expand...
I have not typically but I figured this would give me consistent neck tension. I've ordered the flare die so I expect I'm going to have to use the FCD now.

IMO 300blk subs are more like big pistol rounds than rifle rounds.
 
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Pink_Vapor said:
I STRONGLY suggest it for 300BLK, especially if one owns a 5.56/223 as well to prevent kabooms.
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Running 0.003-4 neck tension has never caused a problem with about 5-6k reloaded rounds.

Neck tension is set by the sizing die (expander ball). Adding crimp can/could cause the brass to bite in to the bullet inconsisently due to neck thickness,hardness, mix match head stamps, etc.
 
My 300BLK does great with the crimps. It's the only cartridge I crimp, I do so just in case a 300BLK round makes it into a 5.56/223. I do not want the bullet pushed into the case and allowing the bolt to close--> KaBoom
 
Djstorm100 said:
Running 0.003-4 neck tension has never caused a problem with about 5-6k reloaded rounds.

Neck tension is set by the sizing die (expander ball). Adding crimp can/could cause the brass to bite in to the bullet inconsisently due to neck thickness,hardness, mix match head stamps, etc.
Click to expand...
If I use the flare die I'll have to crimp, right? I'm assuming the only valid order would be sizing/depriming > priming > flaring > charging > seating > crimping.
 
Coated heavy bullets in 300blk... I wouldn't be expecting much less in SD. Did you weigh the bullets out and sort them? Cast bullets tend to have quite the spread in weight. Coated means they don't have a nice even jacket on them. I'd rather shoot a regular lead bullet than coated if I'm going for accuracy. (Yes I know, you're shooting through a can so coated makes sense) Before you over think things keep in mind it's not an efficient cartridge and check your bullet weights.
 
Flashpoint said:
I've been reloading for a few years but only sporadically, both rifle and pistol. Like many things, I don't spend enough time at it to get good at it. My loads are always pretty inconsistent, sometimes wildly so, at least compared to factory ammo.

Labor day I was at my range taking my first shots with my new Ruger American in 300blk. I had a few Remington subs and some of my own I had loaded with coated 220gr over 7 to 7.8gr in .2gr increments, five of each. My StdDev=22fps, Spread=50fps approximately for 5 shot groups while the factory loads were 1/10 of that.

I weigh every charge using an inexpensive digital scale. It could be the scale but I just think there might be more going on, like inconsistent neck tension or crimp, etc.

I suspect the scale because I notice the tare value wavering .1-.2gr sometimes before I set the powder cup back on it but it always returns to zero. Would an inaccuracy of .1-2gr cause that much deviation?

Anyone have any suggestions as to the best place to start?
Click to expand...

Ha here is mine

Untitled by Brandon S, on Flickr

Untitled by Brandon S, on Flickr

This is with Hornady 208gr BTHP match stuff.

As you can see as I upped the powder charge it spread a little more. But the accuracy is acceptable as these loads are not going to be shot over 50-75 yards.

BTW I use a digital scale from Hornady and have been using it since I got into reloading.

Maybe it's just the nature of the beast as with my 6.8 the spread isn't as bad and that is with both AA2200 and RL10x and the groups are great as well
 
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