Date: 24 May 94  17:22:58
From: Ed Harris
To:   All
Subj: Testing .22 Ammo

Inexpensive Doesn't Mean Inaccurate....

Test samples and buy a bunch to get the best .22s for the buck

By Ed Harris  (Rev. 5-24-94)

If you don't live near a well-stocked gunshop, your only source
of .22 LR ammunition may be the local hardware or discount store.
Old stock in small stores may have been around a long time, but
if the bullets are not oxidized, buy it if the price is right. 
It's probably OK.  Chain stores always have "fresh" ammo, but
seldom carry  anything but "High Velocity" .22's.   Standard
velocity is generally more accurate, but is difficult to find
except at gunshops catering to competitive shooters. 

Most .22s sold are fired in semi-automatic rifles and pistols by
casual shooters.  Mass marketers gear their pitch to the shooter
who is not technically sophisticated, but simply wants the most
"bang for the buck".  "High Velocity" long rifle "solids" outsell
all other rimfires combined.

There is little difference in manufacturers' suggested retail
price between "High Velocity" and "Standard Velocity" .22's, but
considering availability and discount pricing, "High Velocity"
ammo is generally cheaper, unless you order standard velocity in
case lots from a major distributor.

The average user has no control over ammunition manufacturing
variables, except to test batches and to buy the most promising
lots. Therefore you should pay attention to "lot numbers." and
shoot an entire box of ammunition "for group" in your own rifle
before stockpiling a large quantity.

"Lot numbers" are used on almost every manufactured item you
purchase.  An ammunition "lot" usually indicates a day's
production, and indicates to the manufacturer such things as the
year and day of manufacture, the shift during which it was
produced, and the loading or packing machine used. Lot numbers
are used to identify process control data, and can facilitate a
recall if a problem is discovered after the product is shipped.

Most .22 rimfire ammunition is far more accurate than we give it
credit. Ammunition manufacturers operate heavily automated
production lines which can produce huge quantities. This has kept
prices low, so .22 rimfire ammunition is still a bargain. 

The manufacture of .22 rimfire ammunition involves dozens of
machine operations. These include progressive die stamping of the
brass cartridge case, stress relief, annealing, then cleaning and
priming; swaging bullets from lead wire; and assembling completed
rounds, by metering the powder charge, inserting, crimping,
knurling and lubricating the bullets. There are also numerous
quality checks of weights and dimensions, and firing of
functional and ballistic tests prior to packaging.

Given its inherent complexity, even low-priced "promotional"
ammunition must still be subjected to the same basic operations
and inspections as "regular" ammunition. Bargain ammunition is so
only partly from lower-cost packaging, and long production runs
which permit economies of scale.  Omitting non-essential
operations, such as plating of the bullet, reduce cost only very
modestly.

The most important factors affecting accuracy of .22 rimfire
ammunition are bullet quality and uniformity of the cartridge
case.  The bullet must be round, as close to permissible maximum
diameter as possible, have its base square to its axis, and not
be damaged in handling or in the loading machines, particularly
the crimper. The web thickness of the brass through the rim
section affects the distribution of primer mix, controls primer
sensitivity, reliability of ignition, and uniformity of the
dimensions governing headspace, all crucial to accuracy.

Bullet weight and powder charge variation, within normal
manufacturing tolerances, is of only minor significance, if the
above factors are controlled. Standard velocity and sub-sonic
ammunition have somewhat less wind deflection, but in terms of
pure accuracy, whether the ammunition is "Standard Velocity" or
"High Velocity" doesn't matter, if "all other factors are equal".

Industry standards require .22 Long Rifle ammunition average 3"
or less extreme spread at 100 yards for 10-shot groups. US ammo  
producers easily maintain 2" as a product average. The best lots 
will average 1-1/2" or better at 100 yards from the test barrel,
and these are the ones you are seeking! Some US producers test
rimfire ammunition at 50 yards rather than 100, but indoor
rimfire test groups are usually proportional to the range.
"Average" Standard or High Velocity .22 LR ammunition should
average an inch for a series of 10-shot groups at 50 yards.  The
best .22 ammunition should do 3/4" or better from a SAAMI
dimensioned "Match" chamber, in a target rifle with telescopic
sight, fired by a skilled shooter from bench-rest, or by a Master
competitor prone with a sling.

"Sporting" rather than "Match" chambers (in which the bearing
surface of the bullet is engraved as the cartridge is chambered)
usually produce groups up to about 1.3 times larger than the test
barrel, though some individual rifles will give surprising
results. US production .22 Long Rifle ammunition will usually
average an inch or better for a series of 10-shot groups at 50
yards from an accurate sporter.  Specialty ammunition such as CCI
Green Tag  will often do better, frequently under 3/4" at 50
yards, from heavy target rifles, or high grade sporters with
"match" chambers.  When testing, shoot a full box in five
consecutive 10-shot groups, without excluding any data.

It is common for even poor ammunition to shoot occasional "good"
groups, as normal random variation.  Results which appear
meaningful to casual observation very often are not.  You cannot
arbitrarily  discount individual bad shots or groups, because
these are part of the random dispersion and you must look at the
entire body of data as a representative sample.

Age is not critical if the bullets haven't oxidized or the
lubricant dried out.  I have used 20 year old .22 rimfire match
ammo that still produced 1/2" ten-shot groups at 50 yards.  The
limiting factor is evaporation of the volatiles from "grease"
bullet lubricants, and oxidation of the lead bullet itself. 
Minor oxidation may affect accuracy for serious competition, but
it is insignificant for other uses if it doesn't cause leading. 
High grade match ammunition with oxidized bullets can be salvaged
if carefully re-lubed with EP lithium grease, and the excess
wiped off with a patch.

In my experience a freshly-chambered rimfire match barrel doesn't
"settle down" into its best grouping for several hundred rounds. 
Consistency of firing technique is VERY important. Firing several
hundred groups from the bench with a .22 rimfire will teach you a
great deal about "bag" technique,  more cheaply than burning out
a Hart barrel on your heavy varmint IBS bench gun!

Some inexpensive ammunition may shoot very well indeed, but high
price is no guarantee of accuracy. So, it pays to test lots of
any ammunition before purchasing in quantity, to find the most
accurate ones!



In Home Mix We Trust, Regards, Ed



--- msged 2.05
 * Origin: Home of Ed's Red (1:109/120.3006)

