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Tue, Feb. 19th, 2013, 11:52 pm
Getting around .223 shortages.

Originally published at VolkStudio Blog. You can comment here or there.

So our foes succeeded in making rifle ammunition too rare to use for recreational shooting. Most people are now shooting only to zero their new guns, to function test and to get familiar with the manual of arms. The rest of the ammo is reserved for our favorite varmints. But regular practice is important, so consider two workarounds.

The first is a rimfire conversion kit. Fairly cheap, doesn’t require a new rifle. These have been around since the 1960s but the more recent designs are rather more reliable.

The magazine supplied is interchangeable with the standard Black Dog Machine mag supplied with SU22 and Sig522. The kit comes with a bolt hold-open kit. Swapping the parts takes less than a minute.

This is how it looks installed.

Now for the down side: limited accuracy. 22LR projectiles are just a tiny bit undersized for .223 bore size. The kit also has over an inch of freebore, and once the bullet finally contacts rifling it gets over-stabilized. Ideal rifling for 40gr bullet is about 1:16 and slower than that for 30gr. AR15 barrels range from 1:12 to 1:7, with most towards the fast end of that range.  60gr Aguila SSS actually shoot more accurately, but might not cycle the action. Short case also causes some high pressure gas escape from the ejection port.

Accuracy is perfectly acceptable for 25 yard rapid fire practice — around 3″. Point of impact is lower than .223 — and that is the other inconvenience with conversion kits is the need to adjust sights when switching calibers. So this works great for getting used to your rifle manual of arms, less well for precision marksmanship. For accuracy, a dedicated rimfire upper would do better.

This shoots 2″ or better groups at 100 yards, and can be fitted with its own sights.

Correct twist rate and bore diameter coupled with minimal freebore add up to a more accurate upper. The only down side is the higher cost than the conversion kit, but that would be quickly compensated by the difference in ammunition cost.

Wed, Feb. 20th, 2013 06:19 pm (UTC)

The problem is that these can be just as hard to buy as ammo - they're out of stock / on backorder everywhere online.

Wed, Feb. 20th, 2013 06:21 pm (UTC)

It gives me "page not found" for this link - loos like it's not public?

Wed, Feb. 20th, 2013 06:22 pm (UTC)

Should have been public -- was a link to a guy who has these available for reasonable price.

Fri, Feb. 22nd, 2013 12:53 am (UTC)

Still no luck - is there some non-FB link that can be used to reach him? I'd really love to get a .22 upper now that I've run out of pretty much everything else..