P320 X-Five Legion Assistance

[AR_James]

I have a P320 X-Five Legion with a red dot installed.  When applying pressure to the trigger, but before the gun fires; the red dot is moving noticeably up and left as I take the "slack" out of the trigger.  If I hold the pistol where I can observe the slide while apply pressure to the trigger, I can see the slide lifting up in the front/squatting down in the rear.  It is enough movement that it is moving my zero several inches at 18 yards versus the dot's original position before taking the slack out of the trigger.  Is there anything that can be done to prevent/fix this?  

 

Thanks,

James 

 

 

[Boomstick303]

Unfortunately just about every P320 does this due to the design of the pistol. If you watch the rear of the slide as you pull the trigger the rear of the slide will move up away from the grip module. This movement is what is most likely the cause of your dot movement. This is minimized once the mag is inserted and minimized even more with the gun loaded with ammo. Only test the ammo part at the range and safely. As my P320s get older the movement has become also pretty much non existent with the mag installed. I have also noted this deflection is less in P320s with shorter slide and minimized even more with fitted barrels. Or new barrels that have had to be broken in with the matching slide. I purchased a Killer innovations barrel and Norsso slide for a P320 build I did and the gun had to be broken in for the slide and barrel to operate properly. This gun has the best lockup of any P320 I own, because the breaking in process essentially “lapped” the barrel to fit the slide. It is also my most accurate P320. 

[AR_James]

15 minutes ago, Boomstick303 said:

Unfortunately just about every P320 does this due to the design of the pistol. If you watch the rear of the slide as you pull the trigger the rear of the slide will move up away from the grip module. This movement is what is most likely the cause of your dot movement. 

 

Agreed.  This is exactly what I am experiencing.  

[a_whole_lot_of_freedom]

This is 100% a manufacturing limitation. The tolerance of the fit between the slide and the frame is designed to be a little more forgiving because of the "modularity". When any frame is designed to potentially go with any slide you have to either give some on the tolerances or increase the quality of production which increase the price. 

[cheby]

13 hours ago, a_whole_lot_of_freedom said:

When any frame is designed to potentially go with any slide you have to either give some on the tolerances or increase the quality of production which increase the price. 

Not sure about that. Any service pistol would work with any slide from the same model. This is the military requirement. You can install any glock slide on any lower with no issue. It's the SIG design issue 

[jaep1911]

My Legion does that and I have reported that in a different thread some months ago. On the other hand, my X Five does not. The movement moves with the Legion slide. I mean, when I move the Legion slide onto the lower of my X Five, the Legion slide moves up and down on it.

 

Solution? Never shoot with the mag empty.

[cheby]

4 minutes ago, jaep1911 said:

My Legion does that and I have reported that in a different thread some months ago. On the other hand, my X Five does not. The movement moves with the Legion slide. I mean, when I move the Legion slide onto the lower of my X Five, the Legion slide moves up and down on it.

 

Solution? Never shoot with the mag empty.

Perhaps this is why some people report the accuracy issue of the legion compared to X5.

[B585]

1 hour ago, cheby said:

Perhaps this is why some people report the accuracy issue of the legion compared to X5.

Agreed, my Legion is reasonably accurate but not as much as my X5

[BillChunn]

Had the same issue.  The upgrade to the "gunsmith fit" BarSto barrel which was installed by Robert Burke of The Sig Armorer corrected the problem.  Lockup is greatly improved.

 

BC

[AR_James]

1 hour ago, BillChunn said:

Had the same issue.  The upgrade to the "gunsmith fit" BarSto barrel which was installed by Robert Burke of The Sig Armorer corrected the problem.  Lockup is greatly improved.

 

BC

 

Thanks!  

[mrvip27]

5 hours ago, BillChunn said:

Had the same issue.  The upgrade to the "gunsmith fit" BarSto barrel which was installed by Robert Burke of The Sig Armorer corrected the problem.  Lockup is greatly improved.

 

BC

 

How much money are we talking here? and how much of an improvment in accuracy besides lockup?

[chase214]

My slide does the same but when I insert a mag with a snap cap in it the slide does not move down whole pulling the trigger 

[bimmer1980]

It´s the FCU to slide fit in my eyes. You can see the slide lift from the FCU while pulling the trigger. Once it gets spring tension from the magazine (with a round in it) it´s gone. 

 

[BillChunn]

On 4/30/2021 at 9:48 PM, mrvip27 said:

 

How much money are we talking here? and how much of an improvment in accuracy besides lockup?

If you get the barrel through Robert and have him install it, it's $420 although you may have to wait until the barrel becomes available.  He does not keep them in stock.  They have to be ordered and the order isn't placed until your gun arrives at his shop in Texas.  Irv at BarSto is selling them as fast as they are being made.  He said there is a 3-4 week backup if you order through him.  If you find a BarSto barrel elsewhere and ship it to TheSigArmorer, installation / fitting is $175.  A barrel was found online at Springer Precision in November, 2020 for $230 and they sold out within 20 minutes.

 

There is a 30+ minute video on YouTube that shows Robert's barrel installation process.

 

The accuracy improved to a point where two aimed shots on the same target were touching and the others were all A zone hits within 2" of each other.  The 2" hits were on targets that were about 35' away, the ones that were touching were about 15' away.  This was running a stage requiring movement, on the clock. 

 

BC

Edited May 3, 2021 by BillChunn

[CocoBolo]

Interesting, I don't see that on my Glock Open gun, the dot is mounted to the tupperware frame.  Take it out set up a target at 25 yards shoot a few groups from a ransom rest, if your 5 shot groups are within 1 or 1 1/2 you are probably good to go.  If you can stay in the A-Zone at that distance you can hit a small popper at that distance.  You may have to try several different loads if it isn't to be sure.   

[AR_James]

15 hours ago, bimmer1980 said:

It´s the FCU to slide fit in my eyes. You can see the slide lift from the FCU while pulling the trigger. Once it gets spring tension from the magazine (with a round in it) it´s gone. 

 

Agreed, but the movement with mine does not go away after inserting a loaded mag.  

 

[Boomstick303]

9 minutes ago, AR_James said:

Agreed, but the movement with mine does not go away after inserting a loaded mag

 

Is this with the stock Sig Recoil Springs that come with the gun?

 

Under powered springs (or lower power Recoil springs) cause lock up issues with the P320 Legions (most striker fired guns from the limited research I have done).  I will not use anything under a 13-14 pound spring depending on the spring manufacturer in the P320.  I am currently using the Springer Precision 14 pound spring.  It would also seem the springs with more coils, (stock sig and the Springer Precision springs) create a better lock up than normal 1911 springs.  Just a personal observation.    

 

If you are using the stock P320 Legion reoil Springs you might consider sending it into Sig.  At least a phone call is warranted in my eyes.  On a Facebook group and guys sent his back due to what he thought was excessive slop in the slide grip module lock up.  I got off Facebook, so I do not know what the resolution was other than he did send it back to Sig.

Edited May 3, 2021 by Boomstick303

[AR_James]

2 minutes ago, Boomstick303 said:

 

Is this with the stock Sig Recoil Springs that come with the gun?

 

 

Yes, sir.  Set up just like it came out of the box except for adding a baseplate & optic.  

[WaltK]

5 hours ago, Boomstick303 said:

 

Is this with the stock Sig Recoil Springs that come with the gun?

 

Under powered springs (or lower power Recoil springs) cause lock up issues with the P320 Legions (most striker fired guns from the limited research I have done).  I will not use anything under a 13-14 pound spring depending on the spring manufacturer in the P320.  I am currently using the Springer Precision 14 pound spring.  It would also seem the springs with more coils, (stock sig and the Springer Precision springs) create a better lock up than normal 1911 springs.  Just a personal observation.    

 

If you are using the stock P320 Legion reoil Springs you might consider sending it into Sig.  At least a phone call is warranted in my eyes.  On a Facebook group and guys sent his back due to what he thought was excessive slop in the slide grip module lock up.  I got off Facebook, so I do not know what the resolution was other than he did send it back to Sig.

But have you seen a increase in accuracy? Does the gun shoot flat with the heavier spring?

[Boomstick303]

1 hour ago, WaltK said:

But have you seen a increase in accuracy? Does the gun shoot flat with the heavier spring?

 

I have never done a a direct comparison in regards to accuracy using the same ammo same conditions light versus heavy spring. Maybe one day but not anytime soon. I also have not done video testing to see what the heavier spring does in regards to the gun running as flat when I was using the lighter 1911 springs. I did have the gun running super flat with 11 pound Wolff springs.  Springer recommends installation of their 12 and 14 pound springs based on PF. 

 

I have not noted any accuracy issues running the heavier spring.  

 

I am more worried about properly lockup than the gun running flat as it can. I will manage recoil through proper grip and practice.  The dot is not leaving the glass during recoil using the Sig Romeo 3 XL optic.  Accuracy and the gun running flatter is not what’s currently hurting my game. Speed and shot calling is.