Do the .22LR only NAA revolvers have correct bore diameters and cylinder lengths?

Cylinder lengths definitely. A LR model has a shorter cylinder than a magnum, and a .22 short (not an option for BW or Pug, but they make 'em) is even shorter.

I don't know about bore diameter.

The NAA revolver frames are built to house each length of .22. The .22 Magnum has a long frame, the .22 LR a mid-length frame, and the .22 short a "short" frame.
Be aware that only difference between the .22 Short and .22 LR is bullet weight...29 grains versus 40 grains.
The .22 Magnum is of course MUCH hotter than the .22 LR but also the largest revolver at 6 ounces but it does have a larger bird's head grip.
I happen to own the .22 Magnum and find it a joy to shoot and even more convenient to carry!

Be aware that only difference between the .22 Short and .22 LR is bullet weight.

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That is long vs. long rifle.

Left to right this is short, LR, WMR, and the .17s:


NAA has frames/cylinders specific to the first three.

only difference between the .22 Short and .22 LR is bullet weight

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Even if the velocities are the same, the .22 LR (40gr bullet) is going to have ~38% more mass than the .22 S (29gr bullet) and, at the same velocity, more impact energy, better sectional density (weight to diameter ratio). The longer .22 LR bullet tends to "flip" after penetration in ballistic gel and stops traveling base first. (Gives me confidence that the round will do internal damage to an attacking ballistic gel block.)

To me the NAA is the modern equivalent of the "VeloDog", revolvers carried by turn-of-the-centurt cyclists for protection against free-roaming dogs, and if I owned one, it would be .22 magnum because most .22 magnum ammo is more reliable (fewer duds than common .22 LR ammo). The short NAA barrel does not take full advantage of the power of the .22 magnum over the .22 LR.

I have two .22 magnum rifles and while chamber diameter is larger on the .22 magnum, the bullet diameters and bore diameters are the same. I suspect barrel bore diameter is the same for all manufacturers' .22 rimfire models. (Factory ammunition specs for .22 Magnum are .224 inch bullet diameter and for .22 LR are .223 inch.)

Looking at the NAA web site they do have a couple of models that have the "correct" length cylinders. But I see that those guns come only in the shorter barrel length options.

It depends on what you want to do with the gun but if your goal is to reach out a little farther than 10 feet to punch targets, pop cans or small game then I'd suggest go with a convertible model that has one of the longer barrels. The gain in baseline length for the sights will more than make this worth while.

My own 4 inch Earl has managed to make 1.5 inch groups at 12 yards quite regularly. My 20 yard groups tend to fall apart by being up around 6". But that's due more to my "old guy eye'tis" issues than the gun.

All the convertibles are going to have the longer cylinders of course. But I'm more than happy with the accuracy which is limited by my ability to hold the gun and my eye sight. With the gun being accurate enough that I'm the limit the rest is academic.

Carl N. Brown said:

To me the NAA is the modern equivalent of the "VeloDog", revolvers carried by turn-of-the-centurt cyclists for protection against free-roaming dogs, and if I owned one, it would be .22 magnum because most .22 magnum ammo is more reliable (fewer duds than common .22 LR ammo). The short NAA barrel does not take full advantage of the power of the .22 magnum over the .22 LR.

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I have been looking at getting one of these NAA revolvers for exactly that purpose, cycling gun.