Following up again on the topic of .22LR ammunition for the Browning Buck Mark, I have taken a little detour into comparing the Buck Mark with a Ruger, specifically a 22/45™ Target (http://www.ruger.com/products/2245Ta...ets/10158.html), to see how the two guns compare in terms of sensitivity to ammunition. The Ruger 22/45™ has exactly the same action parts as the Ruger Mk III: it differs mainly by having a composite frame, different grip angle, and a couple of minor changes to retain pins in the frame.
Using the same basic test for the Ruger that I used with the Browning, the results are tabulated below. The Ruger digested everything that I fed it, with one malfunction: a misfire that could only be attributed to faulty ammunition. The round fired on the second attempt when it was re-chambered.
FTE in 20 Rounds Make Bullet Type Bullet Weight in Grains Velocity in FPS Power Factor Brand or Description Browning Buck Mark Ruger 22/45™ Federal Round Nose 40 1,080 43.20 Gold Medal Target 7 0 Federal Hollow Point 36 1,260 45.36 Champion 0 0 CCI Hollow Point 36 1,260 45.36 Mini-Mag™ Varmint 0 0 Remington Round Nose 40 1,150 46.00 22 Target 0 0 Remington Hollow Point 36 1,280 46.08 Golden Bullet 0 0/1* CCI Round Nose 40 1,235 49.40 Mini-Mag™ 0 0 Winchester Hollow Point 40 1,280 51.20 USA 1 0 Winchester Round Nose 40 1,300 52.00 Super Speed RN 0 0 * Note: One round misfired, but fired on the second attempt.
So, why is the Browning more sensitive to "light" ammunition, namely the low-powered Federal Gold Medal Target?
It appears that the Buck Mark slide simply offers more resistance to blowback than does the Ruger bolt. I compared the weight of the slides and the approximate amount of spring force applied by the recoil spring, and put the results in yet another small table (below).
Contrary to my initial impression, the Ruger slide (bolt, in their case) is actually lighter than the Browning component.
The spring force estimate was gathered by simply opening the slide of each gun just enough to insert the finger of a trigger pull gauge, pulling back until I saw the slide start to move, and then noting the reading on the gauge. Not precise, I admit, but at least it gave me a rough idea of the comparative spring force involved.
Make Slide Weight in Ounces Recoil Spring Power in Pounds Browning Buck Mark 5.2 ∼4 Ruger 22/45™ 4.8 ∼3.5
So, I conclude that the combination of a lighter slide and a lighter recoil spring gives the Ruger the ability to cycle lower-powered “target” ammo better than the Browning Buck Mark.