Throwing charges, weight variance

[Pharmseller]

I use an RCBS Uniflow dispenser to throw charges for my .223. I check weigh every 15th charge or so.

My goal is 23.5 grains but some are 23.4, some are 23.6.

So the question, how much impact does plus or minus 0.1 grain potentially have on accuracy?




P

 

[mtnbound]

I would not be concerned with a .1 of a grain.

 

[Castle Rock]

FA

 

[OXN939]

Disassembled and weighed the components of a partial box of Federal factory stuff I had a few years ago, out of curiosity. Charge weights variation averaged around .3 grains, with an outside spread of half a grain between the min and max I measured. So, for whatever it's worth, everyone getting good results with factory ammo is likely doing so despite a relatively large variance in charge weight compared to what most of us tolerate when handloading.

I always get it gnat's ass to the tenth since I'm mostly loading for hunting rifles, but a lot of loads are probably more tolerant of charge weight variations than you'd think. BLUF, one tenth not likely to affect anything.

 

[EdP]

I loaded some 280AIs yesterday. 55.5 gr IMR 4831. .3gr/55.5 x 100 = .5% How much of a difference do you think 1/2% is going to make? You can do the math for .1gr with your .223 load. I think it will be less than 1/2%.

The above is why developing a load ladder in .2 grain increments doesn't make much sense to me.

 

[waspocrew]

Definitely not enough to make a notable difference at all.

 

[Pharmseller]

I loaded some 280AIs yesterday. 55.5 gr IMR 4831. .3gr/55.5 x 100 = .5% How much of a difference do you think 1/2% is going to make? You can do the math for .1gr with your .223 load. I think it will be less than 1/2%.

The above is why developing a load ladder in .2 grain increments doesn't make much sense to me.

Thanks to all who took the time to reply.

I particularly liked this way of looking at it.

0.1/23.5 = 0.0043 (rounded up). So less than one half of one percent.





P

 

[Mojave]

50-80 FPS.

 

[MikeDeltaFoxtrot]

If your margin of error is .1 grains, you won't know the difference.

 

[11bar]

Sling some powder and go shoot. I think there should be an emphasis on precsion but don’t get to hung up on it. People for the most part can’t shoot better than the ammo anyways.

 

[JF_Idaho]

.5% +/- @2700fps would be around 27fps

 

[TaperPin]

One full grain of varget in a 223 makes roughly 100 fps difference in velocity - it’s not a big stretch to assume 1/10th gr will make roughly 10 fps difference. Not much of a difference for short range use under 500 yards.

 

[JF_Idaho]

One full grain of varget in a 223 makes roughly 100 fps difference in velocity - it’s not a big stretch to assume 1/10th gr will make roughly 10 fps difference. Not much of a difference for short range use under 500 yards.

Just did 23-24gr varget yesterday under a 75eldm 150fps difference.

Should be said that with rounding to 1/10gr +/- you are getting up to 3/10 variation in charge weight.

So in that scenario roughly 45fps.

 

[TaperPin]

Just did 23-24gr varget yesterday under a 75eldm 150fps difference.

Should be said that with rounding to 1/10gr +/- you are getting up to 3/10 variation in charge weight.

So in that scenario roughly 45fps.

I was just going with chrono data from nosler with 77 gr bullet - 22gr to 23gr was 100 fps and 23gr to 24gr was another 100 fps. An additional 10 fps variance from average isn’t much (20 fps addition to extreme spread). I don’t see how it triples.

 

[JF_Idaho]

I was just going with chrono data from nosler with 77 gr bullet - 22gr to 23gr was 100 fps and 23gr to 24gr was another 100 fps. An additional 10 fps variance from average isn’t much (20 fps addition to extreme spread). I don’t see how it triples.

It triples because it round to the tenth. So until you're over .15 it doesn't round to .2
.15 over plus .15 under equals .3