quote:

Is there some reason why it’s suddenly becoming a complaint about the P320? Do the holes not contribute to the same problem with other pistols?

My guess is the current trend of optics on hand guns has exposed the problem to a much larger audience.. hence more bitch'n perhaps rightfully so...

quote:

Originally posted by HRK:
My guess is the current trend of optics on hand guns has exposed the problem to a much larger audience..

That could be a valid point, but my question is why do we hear it only from SIG P320 shooters?

One obvious answer here is that it’s the SIGforum, but with the explosion of interest in optical sights to the point that it seems every pistol manufacturer is making them “optic ready” and many popular makes have chamber witness holes, it seems odd that I never ran across the complaint until this thread. I am, of course, not claiming that the complaint isn’t valid, merely that it’s strange to me that I’ve never seen it before about all the guns that have optical sights and the same type loaded chamber “indicators” these days.

I think this thread is confusing two different things.
The "masshole" at least on the 226 that I have with one is simply a small cut in the barrel hood. It does nothing to the slide.
The LCI as is implemented on the M17/M18 320 guns (my 320 experience not sure if its the same on all models)is completely different. It also has a cut in the barrel but it also has a substantial cut in the slide that houses an LCI "flag" (that sticks up when loaded) on an axle and a spring. I presume the design goal is both a visual and a tactile check which the barrel hood version cannot do. When removed its a big slot in the slide literally pointed at the optic on certain mounts. To fully get rid of the LCI you will have to change barrel and slide, though I have no idea if the slide side is irrelevant with an non LCI barrel as I don't have one to look at.
I don't own any guns other than the M17/M18 that have this kind of setup so I can't comment on what they might do to the issue of optic debris. I just leave the LCI in and its a nonissue on that front.
But it may be worth saying that certain optics shape cause more problems than others. For example an RMR on a bobro plate is not particularly problematic, but an SRO on a c&h plate is.
All FWIW and YMMV.

quote:

Originally posted by hrcjon:
(my 320 experience not sure if its the same on all models)

It is not.

Most P320 pistols do not have the pop-up piece that is truly an “indicator.” What I believe most of us are discussing (I am, anyway) are the unmolested slides without the indicator, and the barrels that have a slot/hole cut into the barrel hood extension that allows looking down into the chamber to see if a cartridge is there. Because the slot in the barrel hood is just open to the chamber, supposedly gas from the discharge can blow back up and out and leave deposits on an optical sight.

The original slide of P320 XCompact I have has the real indicator, but I have six other slides that don’t have that mechanism. My agency also has over 20 P320s whose slides do not have the indicator mechanism, but whose barrels have the open slot.

Or did I completely misunderstand what you are saying? Or did I completely misunderstand what everyone else is talking about?

OK. So I didn't know they are witness hole only ones. Unlike most things sig I don't have too many 320 so I don't have one with only a witness hole to have any experience. The ones with the flag if you remove it are terrible for optic debris for some optics on certain mounts. That is the extent of my actual experience I can supply on this issue for 320. I can say that on the P226's that I have had milled with the witness hole and an RMR there is nothing special to report.

I have a carry length 13.5 LH threaded barrel without the LCI slot. Got it from Osage County Guns last year (or maybe 2020) for a great price.

Sig often doesn't make sense. You cannot find a full size P320 threaded barrel with the LCI cut. If you want to keep the LCI in your M17 you need to cut the slot in the barrel hood. But you can get carry length barrels either way. Just have to search all threaded barrels on the Sig Store and find the correct part # and then search around and see what's in stock.

If they're going to have an LCI, why add ugly forward cocking serrations? Belt and suspenders.

Being curious about the issue of soot being deposited on the top of the slide through the loaded chamber viewing slot in the barrels of P320 pistols, I took note of mine after a range session today. The pictured unfinished stainless steel slide is from a P320 Carry model chambered for 9mm. I cleaned the slide before the session, and then fired 84 rounds of training ammunition, mostly 115 grain Blazer aluminum which some shooters claim is unusually dirty.

The below photo was taken before the top of the slide was cleaned after the session, but my hand may have contacted that area when performing reloads during today’s drills. I would have expected, though, for any effect that that contact had to be uneven and to leave at least partial visible residues rather than being perfectly clean. The darker band in the center of the slide is an artifact of the lighting that consisted of flood lamps to the left and right of the setup. It is not visible residues.





After photographing the slide I scrubbed it with a white cotton patch saturated with 99% isopropyl alcohol which is an effective way of removing soot-type firing residues. The patch was only faintly discolored. By comparison I used a clean patch on other areas of the slide, including forward of the ejection port and on the sides. Significantly more dirt/residues were transferred to the patch from those areas.

My experiment doesn’t demonstrate anything about the possible effect of firing residues through the loaded chamber viewing slot onto optical sights because different mechanisms may somehow be involved (even though it’s not clear to me what they would be). It was, however, consistent with my previous experiences with the lack of firing residues’ being deposited on the slide itself behind the slot in the barrel hood extension.

Well my Sig compact threaded barrel arrived without the LCI cutout.