With all the discussion of comped guns lately, I thought I would give it a go. I borrowed a buddy’s Roland Special (Glock 19 ATEi worked slide, KKM barrel and comp, stock recoil spring). I shot a lot of rounds from retention. I shot 4 different kinds of duty/carry ammo in 124gr and 147 gr and 6 different kinds of training ammo in 115 gr and 124 gr.
I had no problems free style or strong hand only with any of the ammo. From retention with a high thumb pectoral index, I had lots of problems with the training ammo and less with the carry/duty ammo. The malfunction was a consistent failure to feed. The gun cycled, but on the way back, the nose of the bullet got tipped up against the the top of the chamber, failing to feed.
I did not find the blast from this comp to be a problem after a few rounds. It was noticeable, but it did not interfere in any meaningful way. Some of the hotter duty/carry loads were more noticeable than others.
In all, I shot about 250 rounds through the gun in a fairly short time frame. At least 150 of those were from retention. While a single shot did not bother me, repeated firing at retention bothered me a lot. I stopped firing the gun at retention because I felt like I had smoked a really bad cigar. I stepped off the range to get some fresh air. In hindsight, this was a “Captain Obvious” move. Of course breathing in all the nasty stuff coming from the end of the gun is going to make you sick.
In the end, it don’t believe this particular set up with a KKM barrel and comp would be an issue as a fighting pistol because of the comp. However, I would not do any meaningful training at retention with it due to breathing in all the nasty stuff. Additionally, the reliability issues with ammo is a big concern. If you work at a place that gives you the right ammo or you can afford to always buy the right ammo, then it is not an issue. I don’t fall into that category, so training with a gun set up like this would get expensive fast. Also, cleaning that comp was a pain.