Comp Removal POI shift?

I was discussing comps on Glocks this past weekend and got to thinking. If rifles experience POI shift with removal or exchange of muzzle devices, do pistols experience the same? With rifles there's torque involved. Pistols not so much, not that I've encountered beyond the PMM anyway. Would it cause a shift if there isn't any torque involved with the installation process?
 

Stanislao

Regular Member
From an engineer I spoke to, even changing barrels between flush, compensator and suppressor won't matter in a pistol. There probably is a POI shift, yes, but hardly the most significant factor that goes into missing with a handgun.

Rifles are a different matter entirely largely because they are far more accurate mechanically and practically. Technically the short barrels supported by the slide in pistols will also have less flexibility than a rifle barrel, but as mentioned previously that's not going to matter much.
 

Brad Trittipo

Regular Member
Shot my pistol on Monday at a class with a comp, removed the comp Monday night, and shot the pistol Tuesday. At least in my hands, there was no change in zero. The comp was installed with set screws and Vibra-TITE.
 

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Smith

Regular Member
Comp related question: in your experience, does maintenance or reliability suffer w/ the comp? I have kind of thought about a comp in the "why not" sense, but I've heard that 115gr ammo might not fire as well and other stuff. I'd rather not get the extra flatness if I have to start buying more expensive training ammo.
 
Comp related question: in your experience, does maintenance or reliability suffer w/ the comp? I have kind of thought about a comp in the "why not" sense, but I've heard that 115gr ammo might not fire as well and other stuff. I'd rather not get the extra flatness if I have to start buying more expensive training ammo.
I use the Agency 417 Dual Port comp on an ATEi milled 17 with stock springs and have encountered zero issues. I was comp-curious and saw Cowan's video on it. In it, he stated he's tested it with different ammunitions and spring weights, including the OEM, and had no problems with reliability. My personal results mirror his. Granted, he's shot way more through it than I have so take what I say with a grain of salt.

Maintenance wise, I don't have to clean my x300 every time I shoot which is nice. Other than that, nothing's changed. Still lube when it needs lube, clean when it needs to be cleaned. I've mostly shot 115 through it without a hiccup but as of late I've been feeding 124 through it on a regular basis since there's no price difference between the two at my local stores.
 

Brad Trittipo

Regular Member
In my experience comps work until they don't. If you shoot a variety of ammo, you will have issues. If you find the ammo that works and only shoot that ammo, you will be in good shape.

This is from my AAR of the Kyle Defoor class I just attended:

My Glock 19 with the Zev Barrel and Primary Machine Comp was the same setup I used for Modern Samurai 2 Day Appendix and Hilton Yam’s 2 Day Red Dot. I had run Winchester 147gr NATO in the first class and Bobcat Armament 147 and 124gr, some Winchester NATO and some Federal 115 in the second class with no gun issues. This was about 800-1000 rounds on this setup. I have also shot 124 gr X-Trem copper plated bullets that I have reloaded with 5.3 gr of Unique and Winchester standard small pistol primers through the gun when testing ammo. I had replaced the factory recoil spring with a 13lbs recoil spring when I initially built the gun. I started Kyle's class with Bobcat Armament 124 grain, approximately 3 mags full, and switched to PMC 124gr Bronze that I had bought a case of to take the class. I had mixed one mag with PMC and Bobcat Armament as I ran out while loading the mag before class.

I started the class with no issues other than my poor shooting due to failing at the red dot fundamentals I had learned from two of the best in previous classes. When I hit that 4th or 5th mag loaded with a mixture of rounds the trouble started. Once I hit the PMC the gun would stovepipe every round to every two to three rounds. The ejection pattern changed from 3 o’clock to the right and behind me to 12 o’clock forward in front of the muzzle. The slide had recoiled enough to the rear to load another round and cock the striker, but it was catching the spent round in a 12 0’clock stovepipe. When I completed a malfunction clearance, I would get a live round along with the spent case that was stovepipe. This went on for the rest of the day until I switch to my Glock 22 to finish out the last two hours of class. I was not happy losing live rounds in the grass at the current prices. Kyle said it and I knew it; it was a comp issue. I got to say the fateful words, it has always worked before. I got home that night and removed the comp from the barrel, returned the factory recoil spring to the gun, and went back to class the next day. I can say with confidence, that a comped 9mm shoots a lot softer than a stock Glock 22 40 cal.

The next day I had zero gun issues and completed the class with my 19.
 

Smith

Regular Member
Thanks for those insights.

I've definitely had ammo related issues even w/o a comp. On my VP9, using reloaded ammo off the internet, I couldn't finish a mag without getting a malfunction. Stovepipes, primer failures, divebombs (or whatever it's called when the round is facing DOWN in the magazine).. when I use high quality factory ammo, the gun will run 2,000 rounds with no issues.

I think of it in terms of stacking, I seem to get a little more issue with weird ammo than Glocks do. E.g. when I did a class using frangible rounds in a simulator, I got several malfunctions per mag, whereas none of the Glock folks did (a Sig shooter also had malfunction issues). This makes me think the Glocks are more tolerant of low-quality/load ammo than my VP9. If I added a comp to the VP9, I assume it would get even more finnicky. The Glocks might tolerate a comp better.

Does that sound right?
 
So a year-ish later I figured I would update this thread. Removed the comp and when to check zero. There was an approximately 5.5" shift right and about 2" shift down. Ammo used was the same, 124gr 9mm HST.

Pretty interesting
 
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