Sorting 22lr bulk ammo for accuracy... somthing to think about

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FredTheDog

Guest
ok, I know this subject gets beat to death, but...
I tend to read all I can about a subject prior to getting my feet wet. So searching for actual results and best common practices I continually come across the following sorting procedures, listed in perceived order of usefulness..

1. rim thickness: measuring the rim as if the round is in a chamber to determine headspace (and possibly varying primer compound concentrations)
2. overall weight: simply weighing each round to create uniform batches
3. bullet diameter: measuring diameter of projectile to ensure uniform pressure spikes

The problem with this theory is that, if you are using $20 per 50ct ammo, you would need a $3k weapon and 20yrs of experience to notice minimal gains...

If you are like most, you have a fairly accurate factory 22lr (rifle or pistol) and you are trying to eliminate fliers in bulk ammo such as CCI, Winchester, etc. the best single measurement you can make to sort this ammo is RIM DIAMETER...

bulk 22lr is usually formed from a standard cup being formed into a case. deviations in this process cause many problems, such as ignition differences, headspace differences, extraction issues, and failure to fire... SO...

Sorting by rim diameter FIRST (or only...) will net the most significant gains in accuracy. I have seen as much as a 240fps difference between 36gr Winchester which had .014 difference in rim diameter prior to firing.

in the next couple of days I will post photos of rounds prior to firing, chrono readings, and groupings... so keep in mind I'm just a backwoods hick, not a benchrest shooter, so please keep criticism/suggestions kind.. I'm just trying to help the ones that cant afford Eley, Lapua, etc.
 
Bulk ammo is still bulk ammo. You best yield will probably come from quality training ammo or lower priced match ammo..........but, knock yourself out.
 
You should post on the rimfire forum here or at rimfirecentral.

There is no one answer to sorting 22 rf ammo.
If i sort cheap ammo for my cheap rifle, i can see an improvement.
If i sort top of the line eley or lapua for a 22 match rifle, i cannot see an improvement.

Way to many variables for a single answer.
 
That is exactly my point and the reasoning for choosing the factory rifle forum. Most people that sort 22lr are looking for gains with their 10/22 not their custom chambered remy 40x. but when they look for help, the answers come from benchrest shooters looking for a .009 improvement.

sorting by rim diameter on cheap bulk ammo will get .100-.500 gains, where sorting eley or lapua is a moot point for the vast majority...(if they have the equipment to measure such incremental variances...)

if you have two cartridges, both .038 rim thickness, the larger diameter rim will most likely have a higher peak at ignition. that changes the way the bullet travels the barrel, and group opens up.

factory rifles will see more benefit from sorting and sorting by diameter, then the other methods, if you choose to will eliminate the perceived need to shoot expensive rounds through a factory rifle/pistol.
 

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photos above are from same, batch/brick/box of 36gr Winchester, prior to sorting/post sorting 10/22 groups will have to wait until the rain slacks up..
 
first round

so after finding the most common sizes of base diameter for my lot, I picked 10 random rounds from the sorting trays of the .263-.267, and 10 from the .272-.275...

had a dirty barrel to start so I made three passes with a brush and rem oil, then two dry patches and only fired a single fouler between each group.

rifle is a 10/22 with green mountain barrel, Hogue stock, 3lb 7oz average trigger pull, and a tasco pronghorn scope...(not a BR, but sure works on gophers..)

results
 

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second round

same cleaning/fouling procedure..

sorted the .273-.275 base diameter batch by projectile diameter.

.220-.222 and .223-.2445 (none measured .2225 consistently, used a concentricity gauge to sort into rough groups...)
 

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third round

I picked the .220-.222 group as the best option for sorting by base thickness, they ranged from .364-.370 but I also weighed them so I used the 10 that were most consistent in weight and base thickness together.

results: group went from 1.37" @ 50yds to .82" @ 50yds
 

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I think that if you find improvement, and are willing to expend the extra effort; good for you. If you run into criticism, accept it for the positive aspect; at least they read your work and are willing to comment. If you come up with something else others can use, keep on posting it.

IMHO, the only bad day is one during which I fail to learn something new. Who says it needs to be earthshaking?

Greg Langelius
 
FredTheDog said:
I picked the .220-.222 group as the best option for sorting by base thickness, they ranged from .364-.370 but I also weighed them so I used the 10 that were most consistent in weight and base thickness together.

results: group went from 1.37" @ 50yds to .82" @ 50yds
Click to expand...

Fred,that is s significant improvement.... would be a good regiment for people cometeing in Barnyard Benchrest... where ammo is limited to el cheapo....... and as a last note.....don`t be discouraged by rude replys.............
they are but a few and know not what they do........ they get weeded out by Wilbur....
 
Are you really trying to convince yourself much of anything from one or two groups?
Out of curiosity, are you shooting these ver flags?
For what it's worth, I know of few if any full on bench guns that will settle right in grouping after a cleaning, with a single fouler, let alone factory guns.
 
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Confusion

It appears there is some confusion relative to how rim thickness is measured. The photos with the dial caliper show the rim diameter being measured. Attached is a photo of my rim thickness gauge. Yes, sorting by rim thickness does make a difference in produced accuracy.
IMG_2070.jpg
 
still perty funny to see some dude measuring "thickness" that way...... that said, I guess "thickness" was exhibited ;)
 
Read the post before joining a pecking party.

alinwa said:
still perty funny to see some dude measuring "thickness" that way...... that said, I guess "thickness" was exhibited ;)
Click to expand...


From the original post: If you are like most, you have a fairly accurate factory 22lr (rifle or pistol) and you are trying to eliminate fliers in bulk ammo such as CCI, Winchester, etc. the best single measurement you can make to sort this ammo is RIM DIAMETER...
 
davejones said:
From the original post: If you are like most, you have a fairly accurate factory 22lr (rifle or pistol) and you are trying to eliminate fliers in bulk ammo such as CCI, Winchester, etc. the best single measurement you can make to sort this ammo is RIM DIAMETER...
Click to expand...

Well Said DAVE!!!

I stand corrected, apologetic and dripping crow feathers.

THANK YOU!


al

crawls back under his rock, chastened and subdued
 
I can’t post pictures of the rim thickness gauges we sell but I can tell you that we can see the difference between thicknesses on target and this is with a factory rimfire rifle. So thickness matters. I’m wondering now is diameter changes the thickness in the chamber of the rifle by causing the outer diameter to ride a little higher in the chamber. Interesting stuff. I’ve never measured variations in diameter…….something else to worry about.
 
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