5% again

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  • Last Post 06 December 2017
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Ross Smith posted this 02 December 2017

I have been thinking about the 5% leeway in powder charges that was discussed in my last post. I wonder if we have the same leeway in the other components? I think not. I think our cases and bullets need to be as uniform as we can make them within reason. The benchrest-accuracy guys will be more picky than the soup can shooters, but we still need at least a certain amount of uniformity. I was loading my 223 cartridges and noticed the difference in powder levels in the cases. They were compressed powder loads so the level in the necks was easily noticed and the difference was notable. They were weighed charges. The difference in my opinion was volume or case capacity. All cases the same head stamp,trim length and full length sized. Made me think about the 5% leeway. All the little differences just might be additive. What do ya'll think?    Ross

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OU812 posted this 02 December 2017

Are cases the same lot and shot at the same pressures? Different powder combinations will cause more or less case expansion when fired. I like to fire form cases from same lot with quicker burning powders then neck size using the Lee collet die. I believe neck sizing fire formed cases reduce velocity deviation in bolt action rifles.

AR rifles and automatics require full length sizing. Annealing cases from same lot may help. 

Lapua cases are maybe most consistent in weight and narrow concentricity.

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BigMan54 posted this 02 December 2017

I've found that powder can settle differently in each case. I once used IMR3031 to load some .223REM, some of the cases over flowed the case mouths when dropped straight from the powder measure into the cases.  I changed to a 8" drop tube & hand poured each charge after dropping into the scale pan. I was using new REMINGTON brass. All powder settled to the same level. 

Different method, different outcome.

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

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Ross Smith posted this 03 December 2017

OU812,BigMan54: The cases in question are all the same lot, headstamp, manufacturer,etc. They have been reloaded by me before a few times. After completely reworking the cases by full length sizing, trim to length, and anneal case mouths. I primed them and loaded 27 Varget in them(.223). That is a slightly compressed load. The powder was poured in the cases using a standard one size fits all rcbs funnel. I hold the powder measure pan close so the powder doesn't bounce around while pouring. The powder level varied by about 1/8 inch. That's alot in a 223 case neck. I've tried settling the powder to equal depths and I've also re-weighed the charges as a double check. Case volume is at least partially responsible.

My point is, and my question is, there are variables in reloading that we try to minimize--- and do we also have a 5% margin of error in those variables such as case volume, bullet to bullet weight(do you weigh and sort your bullets)( ever weighed factory J-bullets),etc. Knowing people that re-load with progressive reloaders with good results, I'm surprised that powder charges can vary a little bit but was surprised that 5% was OK. I'm not doubting that ,and it is easily bested by handloaders. That's 5 gr per 100, or 1 grain in a 223 load. My friend with the Dillon doesn't even sort headstamps on his brass, not even military or commercial. 

I'm rambling, I think we need to keep our total accumulative variables to less than 5%. What say yee?

ps: I reload more accurate ammo than he does.

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John Carlson posted this 03 December 2017

Just processed a batch of 500 Remington 30-06  brass.  Weights varied from 187gn to 195gn, or 4%.  The results of the accompanying variation in case capacity won't bother the soup cans, the gophers, or even the deer, but those pesky little dots in the middle of the bullseyes will notice.  As noted, the difference is much less apparent when 1" groups define a good day than it is when 1/2" groups define a bad day.

John Carlson. CBA Director of Military Competition.

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mrbill2 posted this 03 December 2017

How about weighting the cases to see if that could explain the difference in case capacity.

My 2 cents

mrbill2

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Ross Smith posted this 03 December 2017

Yer right: I'll go weigh some of my "culprit"cases and some of my lapuas. 

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Ross Smith posted this 04 December 2017

I weighed more than the Hornady cases involved.This is in no way a big enough sampling to be statistically accurate. That means it isn't data but rather pertinent poop. 

Hornady 223 cases average weight=92.3gr, range 89.4-95.7gr=6.3gr spread, for 6.8% variance

Lapua 223 cases average weight95.98gr, range 95-97 gr, = 2gr spread, 2.0% variance

Denver 1943 30-06 average weight192.2gr, spread 188-197 = 9gr spread and 4.7% variance

sierra 69gr 223 matchkings average weight 69.1 gr, zero variance !

sierra 257 100gr matchkings average weight100gr, zero variance !

speer 30 cal 165spitzer average weight165.4gr spread 164.7-166.0=1.3 gr variance =.79%

hoch nose pour309-220 wheel weight water quenched, gas checked,tumble lubed weighed and sorted into 2 groups,the heavy group

was checked here: average weight216.2, spread 215.7-216.5=.6gr=.20% variance,that's right, better than the speers.

hoch nose pour 309-185 wheel weight water quenched dried, culled, then weighed , this is as cast and only visually sorted

average weight 192.63 gr,range 192.1-193.1=1.0gr spread = .52%variance 

I've never checked this thuroughly before, just culled the uglies and then weighed into heavy and light groups tossing the extremes. Rather than weigh exactly I just use the scale to approximately weigh the bullets by finding a sorta close median weight, setting the scale for it and then sort heavy and light.

This is by no means definitive about anything but does indicate that 5% might just be used as a maximum variance for all components. The data also explains why the really serious accuracy chasers weigh and sort everything.  Ross

 

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RicinYakima posted this 04 December 2017

IMHO, the most important thing is the bullet, form and consistency, bullet fit to the throat and matching those to barrel vibrations. I feel you're good with 5% everywhere else. Now that the mechanicals are taken care of, shoot. Shoot a lot and frequently. Shoot like it is a really long shot hunting or the last relay of a national match. Practice. Just IMHO. Ric

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Ross Smith posted this 05 December 2017

Ricinyakima: I'm with you. 5% is easily bested by us handloaders and I think should be a maximum deviation. I'm not done with this subject ,I intend to weigh some case more lots and post my findings. Not preaching here, just information to think about. Thanks

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John Alexander posted this 06 December 2017

If you really want to how much variation is tolerable in bullets, powder, cases you have to SHOOT to find out instead of having an opinion based on nothing. it isn't hard or complicated.  Shoot groups with your carefully weighed bullets (or cases) sorted to less than 1/10 grain variation as many pontificate as necessary (without having ever shot to find out).  Shoot alternate groups with the culls that very several times that. Shoot enough groups with each and average each. You will find that a lot of the precision in components declared necessary by the wise old heads is BS.  You don't have to take anybody's word shoot and find out.

Joh

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Ross Smith posted this 06 December 2017

John: I did just that yesterday. I just got started that is. Lapua cases for the 223 were a big help, and weighed and sorted 218gr bullets better than unsorted but not so much help from weighed and sorted 30-06 brass. All fun. I was just surprised at the original statement of 5% error for powder. I still think all these 5% errors are additive. So I need to load up some wildly varied cases, powder, and bullets and see what that gets me. I'm not gonna get real involved though. 

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