X5 Legion accuracy

[HOGRIDER]

On 8/9/2022 at 6:06 AM, tim_w said:

A gunsmith fit barrel allows you to fit that lug and the hood.  This locks the barrel in a repeatable position on in battery lockup.  If it has a loose hood and very worse the lug is not sitting flush on the block you will get variation in lockup and as you pull thru the trigger. Bullets go shotgun or shift with fliers

 

Supplied with the Bar-Sto GS Fit barrel:

 

 

[bimmer1980]

On 5/25/2022 at 4:01 AM, tt350z said:

 

The vice jaws pressed on the top of the rails and bottom of the FCU. The rails did spread a little bit as it was pressed down since its an unsupported U-shape. I did have to spread my front rail more than the rear rails as it was sloppier. I just filed/polished the side of the rails until the slide cycled smoothly. Now I have very minimal vertical movement and basically zero lateral movement.

 

I was just shooting factory 115g Blazer Brass. 124g Prvi grouped about the same. Didn't notice a change in group size while shooting standing unsupported except for snappier recoil.

How did you clamp the rear rails? Somehow i find that the nose getting into the grip on the rear makes it hard to press the rear rails down correctly. 

[tt350z]

8 hours ago, bimmer1980 said:

How did you clamp the rear rails? Somehow i find that the nose getting into the grip on the rear makes it hard to press the rear rails down correctly. 

Yes, I had to completely disassemble the FCU to clamp down on the back rails. Front rails can be pressed down without disassembly.

[bimmer1980]

16 hours ago, tt350z said:

Yes, I had to completely disassemble the FCU to clamp down on the back rails. Front rails can be pressed down without disassembly.

Perfect, thanks a lot ! 

[Zincwarrior]

6 hours ago, bimmer1980 said:

Perfect, thanks a lot ! 

You should do a youtube video or such about how to do it. It sounds like a good fix that would literally save viewers hundreds of dollars. 

[USP45]

On 8/16/2022 at 8:16 AM, tt350z said:

Yes, I had to completely disassemble the FCU to clamp down on the back rails. Front rails can be pressed down without disassembly.

Once you clamped the FCU and squeezed it did it flare the sides enough to make the outer portion of the tabs rub against the slide? I did similar to a Glock and while it stopped the vertical movement in the slide to frame fit I then had to lightly file the outer rails as they had spread just enough to rub on the slide where they had spread a little. My X5 has a good barrel to slide fit, but the slide definitely has so.e vertical movement.

[Tampa-XD45]

Has anyone else tried tt350z's "squeeze the FCU rails" idea?

 

Is it to clamp the two areas with green arrows in the FCU pic below?

 

[mpeltier]

I have and it works. I didn't even know about this thread when I started another thread on the same subject as tt350'z did. I actually couldn't get the rails to squeeze in a vice. I had to carefully hammer them down to the dimension I wanted then I had to refit the rails to the slide with a file. Like His mine grouped like 6-8 inches at 15 yards. Totally unacceptable. When I was done groups were under 2" at 15 yds, and no flyers. It's not a barrel to slide issue.

 

I just don't understand why SIG uses a stamped pos part for the fcu housing on the P320. They at least got it right with the P365 and machine a more precise housing for it. Both of my P365's were far more accurate than my P320.

[lawman]

I used the vice clamp method on my FCU as well with success. I took virtually all of the vertical play in slide to frame fit out, I only left a little bit of lateral play for reliable function. Had to file down / refit the FCU rails to slide rails afterwards, otherwise the slide would bind terribly on the FCU rails. However, it had a rather cosmetic effect, I get pretty much the same groups as before, with slow fire at 25m I can do about 3" if I do my part, more or less the same as before. My barrel to slide fit was good from the get-go, no discernible play when I push down on the barrel hood. Honestly the biggest effect on the size of my groups was achieved by a trigger job - I managed to get down to 2.5lb with about 3.5mm reset and buttery smooth pull, pretty goodtrigge if I say so myself. But for some reason, I am still less accurate with my legion at distance of 25m or more than with a Glocks, XDMs or 1911/2011s for some reason. All in all, I wish the legion had a bit more accurate barrel with a tighter rifling (I found out it shoots best with .358" bullets, my other 9mm pistols are good with .357"), but for the intended purpose (IPSC shooting), it is accurate enough.