Dissecting a 22 wmr

[skin]

With a little time on my hands, I decided to analyze the 22 wmr cartridge by taking everything apart and weighing and measuring each component.
 I chose the cci maxi mag hollow point 40gr. In my 512 it shoots around 1 1/4 to 1 1/2 inch at 100 yds. Not great but not the worst.
 I'll start with the loaded cartridge. I  chose ten random cartridges out of the box.
Overall length average of 1.330. Longest was 1.335, shortest was 1.319. Extreme spread (es ) .016. Really not bad.
Ogive to base average of 1.1349. Longest 1.1430, shortest 1.1220. ES .021.
Cartridge weight  average 64.39. Heaviest 64.52 gr. Lightest 64.26. ES  .26 gr
 Now we start taking them apart.
 Bullet weight average of 39.94. Heaviest 40.12 gr. Lightest of 39.64 gr. ES 0.48 gr. That's almost 1/2 grain. Most bullets I reload with vary only by .2 grains at the most.
 Bullet length average of .4438. Longest .4465. Shortest .4405. ES .006
 Case length average of 1.0514. Longest 1.0545. Shortest 1.049. ES .0055. Think of bullet pull here.
 Case weight average 17.86 gr. Heaviest 18.00 gr. Lightest 17.72 gr. ES .28 I  had two at the same length  but one weighed. 26 gr more. That suggests the priming compound fluctuates a lot. Not very good.
 Last but not least is the powder.
 Average weight 6.52 gr. Heaviest 6.62 gr. Lightest 6.48 gr. ES .14 gr. Not bad. Most of my scales are calibrated to .1 grain.
 Looking at all my data, the manafacturers would qc their bullets and priming we could enjoy more accurate 22 wmr ammo. Ammo from 10 to 12 years ago were more accurate than now. Better qc then?

[Tok36]

Interesting stuff.

[skin]

 One other thing I learned from this, there's no meaningful way to sort this ammo for better accuracy. Too many variations.

[david s]

Ammo from 10 to 12 years ago were more accurate than now. Better QC then ?"

           
Ten to twelve years ago was before the (first) great run on rimfire ammo. I saw a quote by one of the people from CCI where he said they were behind by billons of rimfire rounds and that was to just fulfill there current orders. That was a number of years ago. It's just my opinion but I believe that because of this all the forming and loading equipment and dies were run to there last life. No one wants to stop production to replace and align tools when there's already no chance of keeping up and everyone is screaming "Where's mine". Look how accurate the 17 HMR's were when they first arrived. All new tooling and dies. A fresh production line. If things ever settle down again I believe things will improve or at least I hope so. Another consideration would be using the 22 Magnum as the sample source. The Magnum is a hunting round no match 22 Magnum ammo. If you were to sample some of the 22 L.R. Match stuff things would tighten up. But then you pay a premium for match ammo.

[skin]

 david s, I totally agree with you. I would bet that some lots of ammo shoot great. I shoot Fiocchi 40gr hp advertised at 1910 fps. These are supposedly made by cci.  Out of my cz512, they will group an inch or less at 100 yds. Does cci hold tighter specs for Fiocchi? Wouldn't think so. Newer equipment? Maybe. Just plain lucky? Probably. I bought enough of the same lot to last for years.

[david s]

skin, As you know the different lots of rimfire ammo vary more than a little. Finding a production run your rifle likes and stocking up with that lot saves for a potentially nasty surprise latter on. I think it's Eley that has a service where you send them your rifle and they machine test it with the various different Eley brands and different lot numbers. They then tell you what lot number and label your rifle shoots best and you then buy a bunch of it. The service is set up for serious match shooters so they dont get surprised in the middle of a competition.

[painter]

Killough Shooting Sports is the ELEY owned facility that provides that service.

www.killoughshootingsports.com

[skin]

 I've checked the chambers on three 22 win mag rifles, cz 512, Cz 455, marlin 25mn and all had at least a. 070 jump to the lands. It's a wonder that they shoot as well as they do. A custom reamer and a quality custom barrel fitted by a good smith would certainly help out but how much?  Cost, ouch!