22 lr head space specs

Geri

What are the SAAMI spec for the 22 lr, Go and nogo. Thanks
I have been told that .040 is correct for go, but can find no
information on this. Thanks.

Hawk Carse

https://saami.org/wp-content/uploads/2018/01/Z299-1_ANSI-SAAMI_Rimfire.pdf#page=8

Geri

Thank you.Got it.

truthful

The thickness of the rim can impact the effective head space. Uniformity may have improved these days, but "back-in-the-day" there used to be a fair amount of variability in the thickness of the rims on 22LR cartridges. There was variability between manufacturers, lot-to-lot, and even within a lot. We found match ammo to be the most consistent. Some guys would use a rim thickness gauge to sort their ammo. Shooting groups with thin versus thick rims did show a difference in POI.

charliemeyer007

I agree. When the ammo was pack in a box it usually had better quality control than the loose bulk pack crap. I know people that still screen the rim thickness on their 22 LR ammo.

I never worry about for rimfire ammo, I'm just happy if it all feeds and goes bang with the same loudness vs BANG, jam, bang, pip, jam, bang, BANG, dud...

I'm the quality control guy with my centerfire stuff.

mrmike08075

Back in the day (circa approx 1990) the overwhelming concern was variability of consistency from lot to lot and cocentricity...

Those factors were considered of primary importance amongst the coaching staff at the Olympic training center and the serious ranked competition shooters at regionals and at Camp Perry.

Champions choice and other match gear suppliers offered gauges to measure parameters - from simple "no go" to more complex means of data collection.

I tracked much of this info in my shooters diary.

At the OTC they were pulling and weighing heads and measuring powder.

Brand to brand and lot to lot.

Mike

rufe-snow

Another factor regarding 22 RF ammo. Is the sensitivity of the priming compound inside the rim. Which is inserted during manufacture.

I got involved with this when I bought one of the .22 conversion units. Sold by EAA, for the CZ 75 pistols. Believe it was made for them, by Tanfoglio?

To make a long story short. The conversion unit didn't work. When I first installed it. One of it's many problems, was that the firing pin was .060 to short.

To finialy get it working. I had to find .22 ammo with the most sensitive priming.. Testing many different types. I found that Federal, "American Eagle", and "Automatch" was the most sensitive. And Aguila, with ELey priming was the least.

Strangely, other types of Federal .22 ammo. Including "Champion", that was sold as match/target ammo. Didn't have sensitive priming, like A.E. and A.M..

Geri

Hi. I have used the shims to reduce the head space in a ruger 77/22.
It reduced the groups by about 50%.
This was one of the reasons for the original question. Thanks.

Hawk Carse

There was a guy here who ground the 10/22 bolt face to reduce headspace and improve ignition and accuracy.

Geri

There are still people that do that. .0425 is the head space the bolt face is ground to. Years ago I talked to a old gunsmith who said he set the head space to .040 on 10/22s. So what is the correct head space.

RCrosby

I use it only rarely these days, but I have a .22 long rifle chamber, cut from a discarded barrel; breech to a bit longer than my longest .22 rounds. Set cartridge in chamber and use dial caliper to measure over all length. Works great for determining rim thickness, uniformity, etc.
That said, I never did enough testing to determine if my equipment and I were precise enough to judge the superiority of having more, rather than less, uniform rim thickness. If headspace and/or priming sensitivity were problematic it should be easier to assess.
Merry Christmas All,
Rob