Weighing some rimfire

KAZ · Post by **KAZ** » Thu Jun 25, 2009 8:59 am

First of all, I did not do this work, and just copied it from elsewhere. Since we shoot a lot of rimfire I thought it might be of interest. The shooter decided to take a couple hours to open a brick of Wolf Target Match and weigh each round. Here are his results:

51.3 gr - 8 rounds
51.4 gr - 12 rounds
51.5 gr - 16 rounds
51.6 gr - 24 rounds
51.7 gr - 38 rounds
51.8 gr - 44 rounds
51.9 gr - 88 rounds
52.0 gr - 91 rounds
52.1 gr - 79 rounds
52.2 gr - 32 rounds
52.3 gr - 18 rounds
52.4 gr - 14 rounds
52.5 gr - 12 rounds

I'm waiting to see how the different lots shoot, should eliminate some flyers

Post by **Bullseye** » Thu Jun 25, 2009 11:31 am

All things considered, a grain and a half is not much of a variation between these fully loaded rounds.

R,
Bullseye

blue68f100 · Post by **blue68f100** » Thu Jun 25, 2009 3:21 pm

A 1 grain could be a very large % error if its the powder and not the brass/bullet. Lets say the ideal total load weight is suppose to be 52 gr for total weight, but powder is only lets say 3 gr. .7 dev = 23% change. So My guess most of the weight difference is in the brass and bullet weight. Would be nice to have some bullets pulled so you could get actual weights. Knowing the bullet weight we could back some of it out.

bearandoldman · Post by **bearandoldman** » Thu Jun 25, 2009 5:51 pm

Sounds like an awful lot of work and im expended that could be used for shooting said ammo.

KAZ · Post by **KAZ** » Thu Jun 25, 2009 6:07 pm

Well, the original poster said that he had a choice of weighing out the individual rounds OR cleaning up after a Cat with some health issues. Considering those two options I believe you fire up the scale

We all know that there are so many variables in rimfire design that I'm with Bullseye that he will see little difference in group quality.

bearandoldman · Post by **bearandoldman** » Thu Jun 25, 2009 6:41 pm

KAZ wrote:Well, the original poster said that he had a choice of weighing out the individual rounds OR cleaning up after a Cat with some health issues. Considering those two options I believe you fire up the scale We all know that there are so many variables in rimfire design that I'm with Bullseye that he will see little difference in group quality.

In my years of experince have found out the weak link in the marsmanship experience and it is the OPERATOR. Most guns and ammo will outshoot the shooter, even on a good day.

KAZ · Post by **KAZ** » Thu Jun 25, 2009 8:05 pm

I believe that you are so right. The original poster was trying to get some selected match grade rimfire without paying the premium. I suspect that true match grade deals with even application of the primer band, case weight, more careful test lots, etc. blue68 hit it when he posted that without knowing the true weight of the powder charge we don't have enough info to class the selection as match grade. If, he comes back with some targets I'll let you know the results. It still could only mean that he was having a better range day from one day to the next.

greener · Post by **greener** » Fri Jun 26, 2009 12:15 am

The weighted mean for this sample was 51.94 gr. (sum of no. x weight)/(sum of number). The distribution around this mean has some slight tailing below the mean. 246 were >51.94 and 230 were <51.94 gr. The distribution is almost normal. Sounds like the process for this lot was pretty much in control. But you might think that "match" ammo would have slightly tighter tolerances all the way around.

I suspect that additional interesting statistics would be separate weights of case, bullet and powder. This would remove bias from case weights, which may not have much to do with ammo consistency.

If you were going to shoot them for accuracy testing, would you divide them up into sublots based on total weight?

"A Rifleman's Guide to Rimfire Ammunition" by Steven Bolter looked at groupings form many different ammo sources in three match-grade .22's. Ammo from several manufacturers did not produce any recognizable trend in group sizes, they varied by rifle as much as anything else.

As much as I'd like to use this to explain how I shoot, I think, in my case only, minor variations in ammo won't affect my results. As much as I wish.

Post by **Bullseye** » Fri Jun 26, 2009 7:01 am

Good point Greener, I was looking at the range of the deviation not the standard deviation from the mean. As I see it, the standard deviation is about .6 of a grain, which is not much of a difference between loads of the cartridges in the brick. The groupings should be highly consistent based on this data.

R,
Bullseye

bearandoldman · Post by **bearandoldman** » Fri Jun 26, 2009 8:22 am

Greener, I have to agree with your last statement whole heartedly, remember, I have seen you shoot. In reality, I believe it is either; minor shifts in the earths tectonic plate between the shooting line and the target line or; OPERATOR ERROR???????
All that technical talk has me so confused that I am going to have to take Henry to the range and shoot the Hell out of the plastic prairie dog brothers, Petey and Paul.

Post by **Bullseye** » Fri Jun 26, 2009 8:38 am

When you're out blasting those dogs, watch out for the gravitational pull and the Coriolis effect. You wouldn't want those bullets straying off their intended paths.

R,
Bullseye

bearandoldman · Post by **bearandoldman** » Fri Jun 26, 2009 8:44 am

Bullseye wrote:When you're out blasting those dogs, watch out for the gravitational pull and the Coriolis effect. You wouldn't want those bullets straying off their intended paths.

R,
Bullseye

Nope, these are special bullets and are very much tuned to the mass and gravitational pull of a plastic prairie dog.

KAZ · Post by **KAZ** » Fri Jun 26, 2009 10:18 am

I've shot a lot of Wolf Match, SK Match,RWS Target, whatever it is branded at that German factory. It all has been very good with my Annies seeming to like one or the other. The purest benchrest (you all know I'm not) shooters will buy cases of one lot because they know the difference one lot to the other can make. If, one really wanted to waste some time, weigh out a 550 box of bulk. We all have heard the bulk round that barely made it out of the barrel, or didn't work the semi auto action. Some have no powder at all. Anyway there are many shooters reshaping lead,measuring rims, etc in search of the grail of a 22RF bulk round that shoots like the $18 per box fodder. Just shoot a HENRY and it matters not

bearandoldman · Post by **bearandoldman** » Fri Jun 26, 2009 11:03 am

KAZ wrote: Some have no powder at all. Anyway there are many shooters reshaping lead,measuring rims, etc in search of the grail of a 22RF bulk round that shoots like the $18 per box fodder. Just shoot a HENRY and it matters not

It really is amazing how well Henry does on cheap ammo, got to load up and head to the renge to get rid of some more of my hoarded ammo.

KAZ · Post by **KAZ** » Fri Jun 26, 2009 11:51 am

I know, it does assuage the guilt of being an ammo hoarder somewhat to at least recycle. It seems the least we can do