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Discussion Starter #1 (Edited)
I recently bought a newer P320 Compact slide that was "optic cut" compatible because my old one was not. (according to the web sites of those who do this after market work).

I notice significant changes in the slide from older to newer versions and wondered if anyone experienced the incompatibility that I do.

I can get the newer slide on, but it gets stuck, and I have to pull back and rattle it around to get it forward. There's no way it's operational.

See the pics. My slide is on the left and the newer one on the right.

The difference are:
1 - Shiny polished Ramp in the middle is different width and grade (wider one is constant angle, skinny one is varying angle)
2 - Old one has different cutout above the barrel
3 - there's a noticeable piece cutout right under where the butt of the round would be (see it to the right of the front of the ramp on the pic on the right).
4 - Slide lock cutout is longer on the newer slide on the right.

Are there known differences in the FCU that would cause this slide to hang up on my older gun?

Thanks,

Brent

PS - I do have a support case into SIG about this, but still waiting.
 

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I have one of the new optic ready compact slides (about the same machining as you show on yours) . I had no problems getting it on the FCU as long as the recoil spring is perfectly centered in the barrel cut out, if it's off even a little the slide won't go on.

I did have a BIG problem getting the new slide to cycle correctly (it just wouldn't cycle when fired) but it easily cycled by hand.

It looks to me like Sig found a way to reduce machining time by eliminating some machining operations and possibly made it more difficult for a bent ejector to hang up in the slide hole. Mine also has a slightly larger striker bleed-off hole than my old slide.

I ended up cutting about 1/2 coil out of the larger diameter RSA spring and shooting a number of 9mm +P ammo. Once I got it to cycle a little then it progressively got better. After about 700 rounds it is back to cycling like it did with the original slide.

Best I could tell the problem was where the barrel hood rode on the inside of the slide as the new slide doesn't have the center machined out like the original.

Big teething issues with the new slide but once I managed to get it broken in it now works good.
 

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OP, was the newer slide bought brand new or used?

.
.
 

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Discussion Starter #5
I also swapped out my trigger for a flat one and wonder if I put something back together wrong that's catching on the new slide. I may have to watch a video and take the whole thing apart and reassemble. The owl head clicks and stays up when I pull the trigger with the slide off. I feel like I have to push it down to reset it to put my orig slide on without issue.
 

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Unless the Slide Pic does not fully show it it looks like the Slide Voluntary Upgrade Cut on your Slide is different than the new Slide.
Your original P320 Had the Voluntary Upgrade Right?
 

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The RMR cut must lighten the slide enough to where SIG does not have to mill the lightening channels inside the slide to ensure proper function.

Also your barrel may be a tighter fit in the new slide, a tight barrel fit will prevent the slide from going into battery easily and will make it hard to retract the slide once it is in battery.
 

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I also swapped out my trigger for a flat one and wonder if I put something back together wrong that's catching on the new slide. I may have to watch a video and take the whole thing apart and reassemble. The owl head clicks and stays up when I pull the trigger with the slide off. I feel like I have to push it down to reset it to put my orig slide on without issue.
Any chance that you still have the magazine in the gun? (slide won't go on with mag in gun)

Seeing as you had the FCU out & apart try lifting the slide catch lever to do a take down reset before installing the slide.
 

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Bought my 320C back in 2014. Recently bought a Compact RX slide assembly (Romeo 1). I too noted the differences in under the slide. However, my RX slide installed and function without issue.

I also have an SC and FS slide. They too fit and function fine.

I should not that my FCU is still pre-upgrade. I do have the "upgrade" trigger and striker assembly, just no disconnector.
 

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I recently bought a newer P320 Compact slide that was "optic cut" compatible because my old one was not. (according to the web sites of those who do this after market work).

I notice significant changes in the slide from older to newer versions and wondered if anyone experienced the incompatibility that I do.

I can get the newer slide on, but it gets stuck, and I have to pull back and rattle it around to get it forward. There's no way it's operational.

See the pics. My slide is on the left and the newer one on the right.

The difference are:
1 - Shiny polished Ramp in the middle is different width and grade (wider one is constant angle, skinny one is varying angle)
2 - Old one has different cutout above the barrel
3 - there's a noticeable piece cutout right under where the butt of the round would be (see it to the right of the front of the ramp on the pic on the right).
4 - Slide lock cutout is longer on the newer slide on the right.

Are there known differences in the FCU that would cause this slide to hang up on my older gun?

Thanks,

Brent

PS - I do have a support case into SIG about this, but still waiting.

I recently bought a new FULL size optics ready slide with xrays from SIG.

Comparison between my new slide and my 2 other older full size slides:

1 - Same difference as yours.
2 - All 3 have the same cut-out above barrel.
3 - Same difference as yours.
4 - Slide lock seat is same on all 3, but end chamfer changed.

My new slide is fully operational.

Please post results of SIG support case.
 

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Discussion Starter #13
Any chance that you still have the magazine in the gun? (slide won't go on with mag in gun)

Seeing as you had the FCU out & apart try lifting the slide catch lever to do a take down reset before installing the slide.
I actually ran the gun for 200 rounds after the trigger swap.

No I didn't have a mag in the gun.
Swapping to the old slide works fine, then back to new slide and it jams.
 

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Discussion Starter #14
I actually ran the gun for 200 rounds after the trigger swap.

No I didn't have a mag in the gun.
Swapping to the old slide works fine, then back to new slide and it jams.
I played with it some more today and ensured that the mag release was pushed for a takedown reset, and finally got it to go on, but it's SUPER tight... and the last 1/4 inch of the forward travel requires a smack to the back of the slide. Again it's SUPER tight.

I saw another user mentioned shooting +P ammo and it taking hundreds of rounds to break it in. Seriously? There has to be something amiss.

Still waiting on Sig
 

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Discussion Starter #15
Unless the Slide Pic does not fully show it it looks like the Slide Voluntary Upgrade Cut on your Slide is different than the new Slide.
Your original P320 Had the Voluntary Upgrade Right?
Correct, it was a red-box refurb by Sig, bought through CDNN in Sept 2019
 

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I played with it some more today and ensured that the mag release was pushed for a takedown reset, and finally got it to go on, but it's SUPER tight... and the last 1/4 inch of the forward travel requires a smack to the back of the slide. Again it's SUPER tight.

I saw another user mentioned shooting +P ammo and it taking hundreds of rounds to break it in. Seriously? There has to be something amiss.

Still waiting on Sig

Yes, it was me that took some +P, then a fair number of regular rounds before it started cycling on it's own.

The difference is: my 320 did easily go into battery properly (even when it didn't cycle when fired).

You might try some slick grease inside the slide (where the top of the barrel hood slides). Look at your picture above inside the original slide (above the RSA area) where the shinny areas are to see where to grease.

Then cycle it a number of times by hand until it will go into battery by itself.
 

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Unless the Slide Pic does not fully show it it looks like the Slide Voluntary Upgrade Cut on your Slide is different than the new Slide.
Your original P320 Had the Voluntary Upgrade Right?
Agree Buds. Also, every pre-drop-fire slide that has been through the voluntary upgrade program "that I have seen", always shows bare stainless steel where it was milled.

The OP's is black in that area.
 

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Discussion Starter #18 (Edited)
I'm beginning to think a new Recoil Spring might solve the issue. The original seller sent me this:

"Might be of help to you. I just changed out a slide on my xcompact and it hung up in the last quarter inch when racking it back. I changed out the recoil spring assembly and issue was gone. The recoil spring was binding on something when compressed. Don't know if that will fix your problem, but a recoil spring assembly is the cheaper of the fixes I can think of."

And that has also been suggested here as well.
 

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Discussion Starter #19
Sig responded:

"Upgraded and later model slides will have a notch cut out on the underside of the slide to accommodate the mechanical disconnector. If your 2nd slide purchased does not have this, it will not work on your upgraded pistol. If it has it, there can be a break in period to smooth out the notch. Please reply to this email with a picture of your slide, from underneath, and I can let you know. "

I'm directing them to this thread for pics and comments.
 
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