As you know, cartridges are loaded nose first into the XR9 magazine and are extracted from the magazine by their rims as the slide moves through the ejection and loading cycle. The slide is moving at such a great rate of speed that cartridges without sufficient crimp between the case mouth and bullet can experience "bullet pull" with some cases being so extreme that the brass and bullet separate during the loading cycle. I've personally never had this happen to me, but I've seen pictures and video of it happening to others.
One advantage of the XR9-L is a slower slide speed than the XR9-S. The question posed to me was how much difference will the slower slide speed make with bullet pull. The video below covers my test and final findings. The slower slide speed of the XR9-L does indeed reduce the bullet pull in this test. For those concerned about bullet pull, you can compare the difference between the XR9-S and XR9-L. Personally, I'd much rather have bullet pull than set-back. Bullet pull reduces pressure and speed by a small amount. Set-back can increase pressure and velocity to unacceptable levels in extreme cases.
One more test that Arne asked me to consider was running some Underwood Ammo 115 grain +P+ through the L before returning it. I've run this load through my XR9-S in very limited amounts because Arne confirmed that the pistol was safe at the pressures generated by this load. He again confirmed that the L is safe for use with this specific load so I didn't see any reason not to run a few down range and see what the chronograph registered. Recoil and noise were noticeably stronger with these rounds, but the L handled them like a champ.
If you follow the blog, then you know about the unfortunate chronograph accident from last week. As you can see in the videos, that problem has been fixed. When I posted the blog about the accidental demise of my chronograph it was done primarily in jest and also to poke a little fun at myself because I'm human too and sometimes things don't always go as planned. What I didn't expect was two blog readers stepping forward with some generous donations for the replacement chronograph. It was totally unexpected and made me feel really great that they feel that strongly about the content on the blog. Thank you Derek and Brian for your unexpected and very much appreciated support. You made my week.