Sig Expansion Chamber - Gimmick or Feature

[MVS]

https://www.gunsamerica.com/digest/s...p-full-review/

Hard to find much accuracy testing, but there is some in this article

[SMJayman]

I spent 1000 rounds and several weeks with a Sig P365 X Macro. It was about as accurate as I would expect from a pistol that size, and honestly better than I thought it would be. Out of those 1k rounds, I only had one malfunction, and I was running Blazer Brass 115gr ammo, so nothing super hot. It shot pretty flat and not as snappy as a Glock 43x, so in theory that comp/expansion thingy worked, at least some.

https://youtu.be/Bxdrl7XQUn8

[G19Fan]

If I really wanted that pistol I'd just find out of anyone made a long enough barrel, so that I could eliminate the chamber.

In that case why not just get an xl slide

[G19Fan]

re: barrel length.

No. It’s not the barrel length.

I have a standard (3.1”) 365 with a dot and we have multiple 365/365X at work. None have exhibited accuracy issues.

What I saw across multiple Macros / multiple known proficient shooters is the expansion chamber guns would produce two distinct groups, sometimes with a single flier.

I’ve only seen rounds through one P320 expansion chamber gun but it had similar accuracy issues.

A friend of.mind that has had porting done feels.like similar accuracy issues popnup.

[WobblyPossum]

If I really wanted that pistol I'd just find out of anyone made a long enough barrel, so that I could eliminate the chamber.

In that case why not just get an xl slide

Sig offers that as a product already. There’s the P365 XMacro and the XMacro Tacops. It’s just a regular P365XL slide on a Macro frame.

[Sensei]

Sig offers that as a product already. There’s the P365 XMacro and the XMacro Tacops. It’s just a regular P365XL slide on a Macro frame.

This is correct. However, I believe that several people were asking about simply buying a longer barrel and putting it in a slide with an expansion chamber so that the barrel runs the length of the chamber.. I can say that this will not work in the P365 X-MACRO and P226 X-Five pistols. That is to say, you cannot fit a 3.7” P365 XL barrel in a P365 X-MACRO slide. The holes in the expansion chamber will not accommodate the longer barrel.

[GJM]

https://www.gunsamerica.com/digest/s...p-full-review/

Hard to find much accuracy testing, but there is some in this article

Here is some more:

https://www.shootingtimes.com/editor...ion-9mm/485926

[MVS]

Here is some more:

https://www.shootingtimes.com/editor...ion-9mm/485926

I saw that this morning but didn't read it until you posted it here. I would not be unhappy with that level of accuracy. I haven't got to check mine yet. Hopefully I will get the new 507comp sighted in this weekend. I did shoot it in a small local indoor match the other night. One thing that struck me was that no one commented on big balls of flame shooting out of it when we did the low light stages.

[Sensei]

20 Rounds of 124 grain S&B to the head A zone at 12 yards using my P226 X5 STAS at a pace of around 1 round/sec:


20 Rounds of 124 grain S&B to the head A zone followed by 20 rounds of 147 grain HST to the center A zone using my P226 X5 Legion at the same pace of 1 round/sec and at the same distance of 12 yards:


Recoil from the HST was noticeably more stout and you can see that the group opened up to the right as my grip began to break down. Overall, I detect no appreciable change in accuracy between the 2 guns despite the Legion having a wider front sight post.

Recoil was roughly equivalent between the 2 guns despite the STAS being 6 or 7 oz heavier.

[JRV]

12 yards offhand is not an accuracy test.

Bag the guns and shoot at 25 or 50 yards. 50 yards is better.

If those were mediocre, service grade pistols (6” at 50), you’d expect to see a cluster of less than 1.25-1.5” at 12 yards. 4” groups at 12 yards is not really “accuracy” data from which any inferences should or could be drawn, because way over two-thirds of those group sizes are shooter-induced.