Dave Gundry Posted January 21, 2014 Share Posted January 21, 2014 (edited) Hey all,I've got an interesting feeding issue with my Benelli M1. This happens occasionally during a match, but I've been able to replicate it more and more during hand cycling. The shell in the chamber ejects just fine. The next round comes out of the magazine tube fully (seated all the way back against the trigger housing) The lifter fails to lift the next round up and the bolt stays to the rear The round on lifter is fully to the rear The round is centered in the receiver (nose of round is also centered - it is not hanging up on bolt/shell release) Bumping either the bolt release button or lifter un-jams it and the cycle continues normally... This has also been evidenced randomly by a slight delay (~.1-.5 second) in cycling time Lifter pivot pin (also hammer pivot pin) looks to be in good shape Just replaced inertia recoil spring & carrier spring, and problems have worsened in dry fire (have not had a chance to live fire yet). No obvious burrs or wear I originally attributed this to my welded lifter not centering the round in the receiver, but repeated it successfully enough in dry fire to rule out the shell being in contact with anything other than the trigger housing to the rear, and the rim being pinched as normal (?) between the receiver and the back of the shell catch. Edited to add: I reinstalled the original unmodified lifter and the symptoms are still present in dry-fire.I am beginning to wonder if the flipper (bolt breech latch) to bolt interface may be causing the problem and contemplating if polishing the bottom of the bolt groove that catches the latch would fix it. I'd hate to cause a failure to lock back situation though... Edited January 23, 2014 by Dave Gundry Link to comment Share on other sites More sharing options...
AustinT Posted January 21, 2014 Share Posted January 21, 2014 (edited) Edit: NM....gonna leave this one to the benelli plumbers. Edited January 21, 2014 by AustinT Link to comment Share on other sites More sharing options...
Sthrngnr Posted January 21, 2014 Share Posted January 21, 2014 I've had this same problem with a M2. How often do you clean the SG? I never used to clean mine. I noticed after decent cleaning and lube. The M2 functioned like a top. Good luck Link to comment Share on other sites More sharing options...
El Guapo Posted January 21, 2014 Share Posted January 21, 2014 I had this happen this past season. The lifter spring is worn out. Replace it. Link to comment Share on other sites More sharing options...
kurtm Posted January 21, 2014 Share Posted January 21, 2014 I think he indicated that it has a new carrier spring, and while a new carrier spring might mask what is going on a little, I am not so sure that will be the fix. Let me ask Did this problem show up when you got your lifter/carrier welded up? Locking to the rear isn't due to the lifter spring being weak. A new spring might hide the problem of why it is locking to the rear for a little while, but as for a fix...no. Why did you replace your inertia spring?...and once again did this problem show up after or before you got your lifter welded up? Link to comment Share on other sites More sharing options...
GunCat Posted January 21, 2014 Share Posted January 21, 2014 Have you had the carrier latch pin (and carrier latch) out of the gun recently? Is the carrier latch pin fully inserted through both holes in the carrier latch and the latch pivoting freely? Link to comment Share on other sites More sharing options...
bigbrowndog Posted January 21, 2014 Share Posted January 21, 2014 does the gun have a pistol grip stock or normal stock? as kurt asked did this start when you replaced the lifter and if it did did you just put the welded one on without looking at squareness on all aspects? trapr Link to comment Share on other sites More sharing options...
openclassterror Posted January 21, 2014 Share Posted January 21, 2014 Good questions. I think the experts here will get you on the right track, and I will sit here in the corner and listen . Easier to learn when I ain't the one talkin! Link to comment Share on other sites More sharing options...
Dave Gundry Posted January 22, 2014 Author Share Posted January 22, 2014 (edited) I think he indicated that it has a new carrier spring, and while a new carrier spring might mask what is going on a little, I am not so sure that will be the fix. Let me ask Did this problem show up when you got your lifter/carrier welded up? Locking to the rear isn't due to the lifter spring being weak. A new spring might hide the problem of why it is locking to the rear for a little while, but as for a fix...no. Why did you replace your inertia spring?...and once again did this problem show up after or before you got your lifter welded up? It does have a new carrier spring. The delay in cycling and closing the bolt at 'make ready' was first noticed after the new welded lifter was installed. I bought a new one and sent it directly to c-rums so that I could retain my known good factory part just for a case like this. I put the stock lifter back in, and the problem is still present in dry-fire with a clean gun. I replaced the inertia spring (& carrier spring) because the gun is ~10 years old, I've put a few k through it, and I tend to treat springs like 'tune-up' items - they get worn, tired, and new factory parts rarely exacerbate problems in my experience. Have you had the carrier latch pin (and carrier latch) out of the gun recently? Is the carrier latch pin fully inserted through both holes in the carrier latch and the latch pivoting freely? Yes on both counts. The 'D' spring is installed fully and the flipper flops freely. does the gun have a pistol grip stock or normal stock? as kurt asked did this start when you replaced the lifter and if it did did you just put the welded one on without looking at squareness on all aspects? trapr Normal stock. I do notice that both lifters appear to sit slightly crooked in the receiver, see pictures in album link below. No binding present though. Thanks for all the help guys! It is much appreciated! Link to pictures of parts in question Edited January 22, 2014 by Dave Gundry Link to comment Share on other sites More sharing options...
kurtm Posted January 22, 2014 Share Posted January 22, 2014 Sorry to call into question your spring changing, you are of course right, springs can't cause any problem and can only improve over all function...but don't be real surprised if it won't shoot the softer stuff it used to, but you already knew that about inertia springs. Good luck with your fix. Link to comment Share on other sites More sharing options...
Dave Gundry Posted January 22, 2014 Author Share Posted January 22, 2014 No offence taken Kurt - quite the contrary - I greatly value your input as you are far more of a subject matter expert than I... I've hit a bit of a wall in diagnosing this, so I'm trying to throw as much info as I can out there to get to the bottom of it. My spring experience is far more 1911 related than Benelli, so if you recommend reinstalling the old inertia spring, I may listen... Gun has an estimated 4-5k through it (target loads, very few heavy shells). Inertia system was clean upon disassembly but looked like the PO may have had it open (wrench marks on the nut), but when I bought the gun, it looked to have been barely used. Link to comment Share on other sites More sharing options...
kurtm Posted January 22, 2014 Share Posted January 22, 2014 The inertia spring is the short fat one in the bolt and has no " nut" retaining it. Two causes. Carrier retaining pin in backwards. Carrier lever arm bent. Link to comment Share on other sites More sharing options...
Dave Gundry Posted January 22, 2014 Author Share Posted January 22, 2014 My mistake, I was referring to the recoil spring (long one in the tube inside the stock). Link to comment Share on other sites More sharing options...
Dave Gundry Posted January 25, 2014 Author Share Posted January 25, 2014 I noticed a little flat spot worn on the nose of the 'breech bolt latch' (the flipper), so I ordered a new one and a new 'trigger pin bushing' (hammer pin/lifter pin). I inspected the lifter for squareness as best as I could with a caliper and machinist square, and it looked pretty darn good. Replaced both of hose parts, polished up the carrier latch a little more while it was out and reassembled. Gun functions much much better in dry fire I'll have to wait til spring to see if it really is fixed. Thanks again for all of the help & pointers everybody Link to comment Share on other sites More sharing options...
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