Wednesday, August 17, 2011

PHHTttttttt........ a very quiet .22 round.

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At last count I had nineteen different types of .22 rim fire ammunition. This morning, I have to make that an even twenty. Once again I have fallen to the curiosity of an offering previously unknown to me.

This time it is, perhaps, the most unusual .22 rim fire round I have seen. Aguila, a company not afraid to offer something different, brings us it's 'Sniper Subsonic' round with a 60 grain solid lead bullet. Yes.... 60 grains.

The heaviest .22 rim fire normally encountered is 40 grains. Higher velocity rounds usually drop that to 36 grains, or even 30 grains.

Aguila managed to squeeze that huge slug into a long rifle sized package by taking a unique route. They used a .22 short case, with a reduced powder charge, and loaded a very long lead bullet into it, bringing the whole cartridge out to .22 long rifle length. The SSS round looks the part too, with half the cartridge length being lead bullet. That's more than unusual, it's down right strange looking.

The idea is fascinating, with the heavy bullet retaining substantial energy while the low velocity and charge give greatly reduced noise. The problem with this approach is one of bullet stability.

Heavier low velocity bullets require a rapid twist rate to stabilize the bullet in flight. Lighter high velocity bullets can use a slower twist rate to accomplish the same stability. Bullet design also comes into play in the equation. Even the type of rifling can have an effect.

Typical .22 rim fire firearms shooting a 35 to 40 grain bullet at 1000 fps work well with a 1 in 16" twist rate, and this is standard for these weapons. A .223 center fire shooting a 60 grain bullet at 3200 fps usually works well with a 1 in 9" twist.

A .22 rim fire shooting a 60 grain bullet at subsonic velocities? A rapid twist would be in order, and its doubtful that 1 in 16" will do it. The test is simple. Load an accurate .22 rifle with the new ammunition, sight on a reasonable target, and note the results. That is exactly what I did, and the results are shown here.

The rifle chosen was a CZ452 Trainer, and is exceptionally accurate. It has shown a tolerance for various cartridges, without being overly picky about what it will shoot well. The long barrel and deep rifling may have something to do with that, as well as the tight bore. This rifle, even with open sights, constantly surprises shooters with it's consistent ability to group tightly.

Setting simple 4"x6" card stock targets at 50 feet, several rounds were fired. Only a few were needed to answer the basic question. The very first round was a classic keyhole, as was every round after. The Aguila 60 grain bullets simply would not stabilize in the 1 in 16" twist CZ barrel.

Fired at both a paper target and a block of pine, the imprints are clear sideways impacts of a bullet tumbling in flight.

Perhaps this ammunition would be better suited to a .22 wearing a custom rapid twist barrel, as many folks have fitted to Ruger 10/22s. Also, it might be a perfect round for an AR equipped with a rim fire conversion, especially if it has a suppressor can installed. For my .22's, all of which have 1 in 16" twist barrels, I'm afraid this Aguila offering is useless.







15 comments:

dakotas5 said...

Out of a pistol for defense the keyhole round could be very deadly.

Old NFO said...

Ouch... keyholing is NOT good for accuracy...

Gunnutmegger said...

Some companies used to offer 10/22 barrels with a fast rifling twist for this ammo.

Anonymous said...

Thanks...I clicked on two adds for you too!

Carteach0 said...

Lol... Thank you!

Anonymous said...

Dakota...wouldn't count on it for defense.
Along with accuracy, penetration would be compromised too.

Anonymous said...

come to think of it...I also doubt they'd cycle a semiauto...would certainly confirm before I thought about trying.

I know for a fact that the Colibri (20 grain, primer only) will NOT cycle a 10/22 or a Buckmark.

Willorith said...

The accuracy issue as regards heavier bullets is a result of the heavier bullets necessarily being longer - no other way to add weight, the diameter being fixed, and depleted uranium being in the unobtainium group on the periodic chart. When the bullet is lengthened the center of mass moves aft from the center of resistance.

Maximum stability is achieved when the center of mass is forward of the center of resistance, as in a Minie ball, or a hollow based shotgun slug.

To overcome the inherent instability of the COM being aft of the COR. the bullet must spin faster.

I have seen many many .22 LR conversions in ARs on the line at Appleseed events. Never has one of them been up to the challenge of 400 rounds a day of timed fire.

Appleseed instructors always have loaner Ruger "Liberty Teaching Rifles" ready to help any attendee inadequately equipped.

Willorith said...

Do you think you might treat us to some of your Haiku on occasion?

I do miss it.

Carteach0 said...

Willorith, It may happen. If the mood strikes. No way to predict.

Anonymous said...

They work fine in my Ruger 22/45. Not as accurate as I would like but they work OK when shooting steel knock down plates.

Firehand said...

It will cycle a S&W 15-22 rifle; about 1.25" at 50 yards.

I've got a couple of rifles this stuff shoots quite well in, and others it's bloody awful, same results as you.

God, Gals, Guns, Grub said...

I tried these cartridges a while back, and while I had disappointing results from rifles, I had better result from pistols...

While rifling twist rate might be my problem... I have another theory...

I'm thinking the energy from powder charge is used up before the bullet exits the rifle barrels whereas the pistols' short barrels don't have this problem...

If the bulk of the powder charges' energy is exhausted in the first 12" to 14" of the length of the rifle barrel, then thew rifling is just dragging on the bullet the last few inches of the barrel's length and that long bullet had a lot of contact surface with the rifling...

I don't remember the exact fps, but when I chrono'ed the bullets, the pistol fired bullets were exiting faster than the rifle fired bullets were...

Anyway, just speculating and wondering...

Dann in Ohio

Firehand said...

I ran some of this over a Chrony a couple of years ago, out of a Martini single-shot; velocity ranged from 862 to 894 over ten rounds. Ought to try them out of a pistol and see what numbers I get

Willorith said...

We have a coyote problem here in Winter Park FL. It might be worth getting a fast twist barrel for the old 10/22.