I have older 2018 Sig 320 9mm compact, came from the factory with a threaded barrel and suppressor height sights.

I have been shooting this gun with a Dead-Air Ghost-M for a couple of years now. Shoots good, cycles good, even with low power subsonic 147 rounds.

Now my problem— I just bought a new “factory” Sig RX compact slide with Romeo 1 red dot on it. (just the slide, red dot, striker, extractor, no barrel)

I put the barrel and RSA from my original 320 compact into this slide, installed it on the chassis and it just will not cycle with my suppressor on it. I have tried about all 147 grain from white box to Speer lawman 124 and Speer lawman 147 and NOTHING will cycle this gun with a suppressor on it.

I have even tried a couple of 147+P and out of 5 rounds 4 didn’t kick the slide back far enough to even stove pipe (bent case mouth trying to go back into the chamber still stuck to breech but low). The 5th 147+P did cycle far enough to stove pipe.

Slide seems to cycle OK by hand but I can feel a slight catch just after the rear of slide drops BUT it doesn’t feel any different than it did with the stock TB barrel and slide on the gun (no catch felt with empty chamber). My full size 320 TB also has that slight catch and it cycles about anything, even with a dirty Neilson plunger and coked up spring in it.

The Ghost-M I am using has worked flawlessly on the this original 320TB, my 320F TB, all my Glocks that have a TB, my Sig 226 TB, my FN 509 with threaded barrel (this suppressor just works on ANYTHING).

I have tried swapping all the parts (RSA, extractor, extractor spring and rod from the original slide and nothing changed (it still won't cycle)

The new RX compact slide will cycle without the suppressor on it but not with lower power ammo and it is really lethargic ejecting even with high power ammo in it.

I have tried about everything that I know to do (been shooting for over 45 years now) and have cured lots of cycling issues but this one seems to defy logic (at least for me).

All in all I have probably put 150 rounds through this 320 now with the new RX slide and the ONLY time I have got it to cycle correctly is without a suppressor on it.

I even removed the red dot to see if the slide weight reduction would help (no help)

I am going to call Sig but I would like some opinions on this before I call so I can ask the right questions and make informed suggestions when they give me the standard run-around (never heard of this problem, shooting wrong ammo, suppressor problems, moon not in the right sky position, etc).

I have heard of 320 cycling issues using a suppressors before but I have not heard of any good fixes that work (hopefully there is some)

How did you lubricate the new slide and (old) barrel?

Thanks for your response.

I have tried just about all the lubricants that I have available, oils, silicone grease, CLP, TW25b, graphite, 10w motor oil, even tried with it dry. Nothing works lubricant wise.

The suppressor strokes on the piston very smoothly and the slide moves smoothly.

From what I have tried it doesn't seem to be lubricant related.

Perhaps, what little bit of mass added by the Romeo 1 is slowing the slide down just enough to prevent it from cycling properly with the suppressor.

Since you mention you "can feel a slight catch", how many rounds have you run through it without the suppressor? I guess that it's kind of a break-in question...

I know my post was a bit long but if you re-read it you will see that I have already tried removing the red dot. (no change in cycling noted).

In all my testing/trying I probably have an assortment of about 50 rounds through it unsuppressed.

I though about the break-in thing but it hasn't gotten ANY better, you would think that if it was break-in thing I would slowly start seeing an improvement with it going from just re-chambering the spent case to something like moving to a stove pipe.

When was the last time you cleaned your can? Maybe inspect and clean out the spring and piston?

It is possible that the can lowers the pressure so much that even the booster won't help it cycle. Have you looked into an uncaptured RSA? Then maybe pick up some lower weight recoil springs to see if that will help it cycle.

It seems like you have explored everything (based on my limited knowledge of suppressors), but as a last thought, you did lubricate the outside of the barrel, and not just the rails—?

I have tried lubricating EVERYTHING, little lube, lots of lube, dripping wet lubrication, dry, dry lube graphite, about the only thing I haven't tried is using maiden oil.

I'm totally convinced it isn't a lubrication problem-- About all I know for sure is that it is suppressor use related (weight, Neilson device, piston spring, inertia delay, (something), I just don't know.

I even tried the longer threaded barrel, and all the extractor parts out of my good functioning full size 320 (non Sig threaded barrel) and same no-cycle results.

This thing has me pulling what little hair I have left out of my head.

If I missed this im sorry, but did you swap the striker assemblies? I had an issue with a Pro cut slide and it was an issue with the striker. I took it out and cleaned it and i did not have an issue again.

Yes, I have swapped strikers, the one that came in the new RX slide, the one that came out of the host guns original slide, and the one from my 320 full size. (no difference in cycling/ejection)

quote:

I have even tried a couple of 147+P and out of 5 rounds 4 didn’t kick the slide back far enough to even stove pipe (bent case mouth trying to go back into the chamber still stuck to breech but low). The 5th 147+P did cycle far enough to stove pipe.

I would lube everything and hand load one at a time until I had fired 20 or so rounds, see if that breaks it in. Sounds like you have some dimensional stacking between the barrel / slide etc. Many barrels fit no problem between slides and frames, some require fitting for the last few .001, or whatever dimensional tolerance is on a Sig 320.

I have hand cycled WAY more than 20 rounds through it so far and no change. (even one round at a time and no magazine in the gun it will not cycle suppressed).

As far as barrel fit, it seems to fit correctly (not tight in the slide or anywhere for that matter), gun cycles OK with no suppressor so barrel does fit loose enough to allow cycling with no can. (I have hand built and hand fitted barrels to a number of 1911's so I kind of know what a proper barrel fit and lock-up feels like. This one seems good to go.

But, I had thought of that so I did try another barrel from my other 320RX and it acts the very same (no cycle).

The one thing I haven't tried yet is shooting it upside down, won't fix it but might shed some light on what is causing it, so tomorrow I am going to try that.

I have a new SilenceCo compact barrel coming (hopefully by Monday) so that will be barrel number 3 (I will see if that changes anything)-- That barrel is actually for another project but it looks like it will be a test barrel in it's early life.

Wild ass guess: The weight of the suppressor is causing the squared area (chamber area) of the barrel to bind in the top of the slide, just enough to keep it from cycling.
The slide may be slightly out of spec.

quote:

Originally posted by YooperSigs:
Wild ass guess: The weight of the suppressor is causing the squared area (chamber area) of the barrel to bind in the top of the slide, just enough to keep it from cycling.
The slide may be slightly out of spec.

That isn't a bad guess as I have thought the same thing a couple of times now. I just can't find any evidence of that, no strange wear the on front of the slide opening, barrel fit in the window looks fine, slide hand cycles good even with the suppressor weight. I have even hung additional weigh on the front of the suppressor to try to get it to act up (hand cycling the barrel drops down free and easily even with the additional weight up front).

It is unlocking during firing with the suppressor as the round clears the chamber, but it doesn't seem to cycle back far enough to allow the case to hit the ejector so the spent case just stays on the breech, then cycles back into the chamber (sometimes straight back then straight forward into the chamber, and sometimes low so it bends the case mouth as it re-enters the chamber low.

With the above in mind, yesterday, I removed the front section of my Ghost-M to lighten it up but still the same no ejection, no cycle even with a lighter suppressor.

In my post above I mentioned that I plan on shooting the gun upside down (hopefully today if I can get a chance). This should take the suppressor weight off of the barrel hood and possibly prove something (what, I'm not sure of but possibly give me a direction to look in.

At the moment I am thinking that the top of the barrel hood might be dragging on the inside of the slide (not right at the window cut but farther forward). When I hung that extra weight on the suppressor I could feel a strange drag near the end of the slide stroke (just before the round would hit the ejector). But that drag went completely away if I removed the extra weight.

The slide does look slightly different than the original on the top inside of the slide (where the barrel hood top would ride with the slide retracted). The original slide has a machined depression in the center of that area so the top of the barrel would only contact the outer edges on each side. My new slide doesn't have that machined depression so the barrel contact would be all the way across.

I can't see any defining drag marks on the barrel hood top but that area inside my old slide is worn smooth with the slide finish worn off and bright metal showing. (this is an area that I am trying to figure out at the moment).

I am waiting for my new SilenceCo barrel to show up before doing too much more, if the new barrel helps then I'm off to the races, if it doesn't then I'm not sure.

I will probably end up eventually sending the gun back to Sig but I am pretty sure they will want me to send it in with the suppressor and I'm not willing to do that as I shoot that suppressor daily.

One more wild ass guess: The bullet may be striking or dragging on the suppressors internal components. The hit on the inside of the can might be forcing the barrel to drag on the slide.
Hows the can looking internally? No sign of bullet impact?

quote:

Originally posted by YooperSigs:
One more wild ass guess: The bullet may be striking or dragging on the suppressors internal components. The hit on the inside of the can might be forcing the barrel to drag on the slide.
Hows the can looking internally? No sign of bullet impact?

No, no bullet strike inside the can, I have a homemade 9mm exact-fit range rod that I slide through the barrel bore then through the suppressor to prevent things like that.

Plus, I am shooting a Ghost-M, that is .45 suppressor so if anything would get hit it would be the center hole in the front cap.

With all of the above, I would respectfully suggest you pack up everything and send it to SIG. Take a deep breath and include the suppressor. The parts that are causing the problem are all factory SIG, and it’s their job to make them all work properly together. You will find that their customer service is much better than you seem to think.

quote:

Originally posted by Dav:
With all of the above, I would respectfully suggest you pack up everything and send it to SIG. Take a deep breath and include the suppressor. The parts that are causing the problem are all factory SIG, and it’s their job to make them all work properly together. You will find that their customer service is much better than you seem to think.

That would definitely be the best approach but there is just no way that I can live without that suppressor for that long. I shoot a lot so like to keep my neighbors happy.

Plus I shoot a suppressor league once week through the summer (difficult to compete without a suppressor)

I can much easier live without that gun than without the suppressor.

As of today I seem to be making some progress on getting it to cycle (I don't want to get ahead of myself on this so will post follow up when I can confirm the progress)

OK, some follow up on this__

Tried the new SilencerCo barrel and that was a no-go either (but, new barrel, no break-in, no shinny spots yet). So I didn't spend any more time with that barrel as it was ordered for another project.

I put the Sig threaded barrel back in then started on getting it to cycle.

First move was see IF I could even get it to cycle with 147 gr bullets, that I eventually did by putting some toothpaste mixed with Mothers Polish inside the slide where the barrel hood rides with the suppressor weight on the barrel, then hanging an additional weight on the suppressor, then hand cycling for about 50 cycles.

Then a clean up and re-lube. This allowed it to sort of eject with no mag in the gun (single feed) and
using a slower powder with a speed of over 1050 ft/second. (but it did shoot and eject now, sort of anyhow).

So shot 100 rounds of the above 1050+ ft/sec ammo and it did get to the point of sluggish cycling with mag in gun and less than 5 rounds in the magazine. (progress)

Still wouldn't cycle with red dot on the slide.

I had an old RSA assembly laying around from my first 320 compact so I disassembled that then cut 1/2 coil off of the rear of the large spring (this early RSA has an open type rear coil so I didn't have to mess with the tight doubled rear coil of the newer RSA's).

This helped as there was still plenty of spring power to close the slide into full battery with a full mag but did allow cycling of the slide with no red dot and up to 10 rounds in the mag.

I haven't re-tried with the red dot back on the slide yet and it is still pretty sluggish ejecting (even with only 5 rounds in the mag but it WILL now shoot and eject good enough to shoot the gun with 875 ft/sec 147 gr rounds (much quieter than the 1050 ft/sec were).

My plan is to shoot this gun without the red dot for a while to allow more slide break in (probably only 500 +/- rounds through the new slide now) then when/if I start to see farther ejection I will re-install the red dot.

I do think that if I cut another 1/2 coil from the RSA it would cycle with the red dot but this is still a non-updated FCU gun so it doesn't have good out-of-battery-firing protection.

Thanks for the update.
Good luck with the process.