BENELLI KNOWLEDGE!

[P.E. Kelley]

This is a cut and paste from an old (2003) thread. I was looking for other info at the time.

This is worth repeating.

RKGSMITH:

In part you are right, The bolt, under recoil, wants to move forward (actually stay in place, as the gun moves back, seeing as it is so heavy) as the gun recoils rearward. This compresses the inertia spring which then forces the bolt to unlock the bolt head and sends the bolt to the rear. The more recoil the more energy to do these things, i.e. heavier loads. Bracing the stock against a immovable object doesn't allow the inertia spring to compress fully thus causing short cycling. Benelli calls the bolt what most would call the bolt carrier just so we are all on the same page. This is in the unlock and eject phase of the cycle. The feeding and bolt head locking are the next phase we will look at.

If a Benelli is opened enough to eject the empty and release a shell onto the carrier FULLY, it certainly has enough spring energy stored in the main spring (even the light spring) to feed and succesfuly lock the bolt head. 4 things can cause the malfunction you mention and none are related to "short stroke".

1: the cam pin is dry, or worn, or cracked ( I have only seen one cracked)

2: The locking lugs on the bolt head are dry, or they are hitting dirt left in the barrel extention where they lock ( best cleaned with a tooth brush and solvent and Q Tips) or are hitting an improperly machined extention ( had to clean up about 5 guns in this area so far.

3: The bolt is worn in the cam area where it initiates locking and is allowing the bolt to close too fast, instead of hesitating on the flat part of the cam area, causing the inertia spring to compress slightly and "bounce" the bolt back out of battery ( this took me almost a year to track down and figure out on my really worn Benelli).

4: the shell drags on the " throat area" or the sharp spot where the extractor cut is in the barrel causing the carrier to slow to much to lock into the extention.

I always lube the bolt head with a light oil on the inside of the bolt, and I use moly slide from NECO on the cam pin and cam surfaces and the locking lugs. I like to clean every 400 rounds or so and also lube the heck out of the bolt rails with J.P. Enterprises Red lube. I never take a clean shotgun to a match and like to get at least 50 rounds through it befor hand. This has to do with cycling AND patterning!!

The inertia spring doesn't "throw" the bolt back very forcefully with the lighter loads( as it doesn't compress as much as with heavy loads) and this is why ANY sort of bind in the mainspringtube to guide fit will cause short cycling. The spring guide/buffer assembly fits the main spring tube very tightly and can be slowed quite significantly by even a slight deflection of the mainspring tube.

I have been told that Benellis will never run if they have over a 10 round extention or side saddle. I can't vouch for the side saddle, but once propperly balanced I can attest that a Benelli can in fact run just fine with a 12 shot extention with light trap loads! Making for a nice handy 14 shot "open" Shotgun

[Jesse Tischauser]

Wow great read! I did out my 32 round Xrail Benelli against and 8-10" diameter tree and it ran just fine though. Explain that one too me...

[P.E. Kelley]

I bet your Benelli has a gel recoil pad and comfortech stock...both "give" enough.

[CraigS.]

Pat , That's a great explanation of the Benelli enertia system .

You might want to repost this in the shotgun tech section too.

[P.E. Kelley]

Yea, I didn't notice I had this in the rifle section. AND the info is Master Kurt Miller's info, I just cut and pasted.

[kurtm]

Even though this statement seems to be in error, as Jesse pointed out, it is taken as a stand alone statement, it wasn't it was part of a conversation with a previous question and this was part of that answer. Pat's answer is absolutely correct, a good pad or comfort tech stock allows enough movement to compress the inertia spring. Also it said "short cycle", not "doesn't move at all". It takes very little movement to make them work, but back in the old days the M1 (which is the gun we were discussing here) came with a very hard rubber pad, and would short cycle if placed against an immovable object. So you see I wasn't wrong after all. Thanks for digging this up Pat! It is kind of cool to see when some of this stuff was being done!

Edited December 8, 2013 by kurtm

[CJW]

This makes a lot of sense. I had always wondered about the advice that an M2 won't run with a side saddle. After all, we all try to brace our shotguns as much as possible, right? How could extra weight on the receiver hurt that? And the answer is that the receiver does need to move for the inertia spring to compress properly—unlike a gas system that needs to stay still so that you don't rob the piston of rearward momentum. Now all is clear! It makes me like my M2 even more; the inertia system is just too cool from a design and engineering perspective. (That, and no gas ports or pistons to clean!)

Makes me wonder what the relationship is between the stock type (i.e., ComforTech or not) and the lightest rounds you can get the gun to cycle. If I am reading this right, then you'd almost have to have a CT stock to get the 7/8oz loads to work, right? Otherwise the light round wouldn't have enough kick to move the gun against a well-braced shoulder with a standard stock. I have the CT stock and it runs 1oz shot loads and 7/8oz slug loads all day long.

The manual says it will operate with a muzzle energy of 230 kg_f*m, or 1670 ft*lb_f. That gives the following: 1 1/8oz @ 1235fps, 1oz @ 1310 fps, or 7/8oz @ 1400fps. I know for a fact that I routinely run the Winchester AA light target loads, which is 1 1/8oz @ 1145fps, so that's under the specified minimum by a fair amount. My 7/8oz Fiocchi Aero slugs run at 1300fps, also light according to the specs, but I have seen people have issues cycling the 1oz Fiocchis at 1150fps.

So, I see working loads at about 1430 ft*lb_f muzzle energy, but the heavier Fiocchi is way low at about 1285 ft*lb_f. The 1oz load would have to do just over 1200fps to make the same muzzle energy as the other two loads.

Okay, enough math. I am pretty comfortable saying that the operating energy of a ComforTech M2 is about 15% lower than the published spec. I'd be curious to see how much lower than that one can still go, though!

Edited December 9, 2013 by CJW

[openclassterror]

I have a theory that the reason the Stoeger m3000 inertia gun is so forgiving load-wise is the carrier extends forward around the mag-tube because the recoil spring is there instead of inside the stock. This adds mass to the "bolt group" (for lack of a proper term), which resists movement more efficiently than the bolt by itself. Because the assembly weighs more, it stays put longer, which compresses the inertia spring further before "un-springing" for any given load. Mine runs flawlessly with loads that stall Benellis consistently. Not enough of an engineer to claim factual truth, but it seems like the most reasonable explanation to me. I run a 13-shot tube AND a ported barrel, and no cycling issues with light loads, even if I start with a 15 shell ghost load. I swear it loses HALF its weight by the time it is empty!

[Jesse Tischauser]

I have a theory that the reason the Stoeger m3000 inertia gun is so forgiving load-wise is the carrier extends forward around the mag-tube because the recoil spring is there instead of inside the stock. This adds mass to the "bolt group" (for lack of a proper term), which resists movement more efficiently than the bolt by itself. Because the assembly weighs more, it stays put longer, which compresses the inertia spring further before "un-springing" for any given load. Mine runs flawlessly with loads that stall Benellis consistently. Not enough of an engineer to claim factual truth, but it seems like the most reasonable explanation to me. I run a 13-shot tube AND a ported barrel, and no cycling issues with light loads, even if I start with a 15 shell ghost load. I swear it loses HALF its weight by the time it is empty!

How light of loads are you talking? I can run 1145fps 1 1/8 oz in my M2. If love to be able to shoot some 980's in the shoot off.

[APL-G35]

If you want to run 980's get a versamax

[kurtm]

You can set an M1/M2 to run real light loads. The problem is if you put heavier loads in it you beat the hell out of the receiver, or break your inertia spring. I set one up once to run 1 ounce loads reloaded at 1000 fps. Ran fine until we shot a Remington reduced recoil slug. If you have access to inertia springs it can be done, but I don't recommend it, nor am I going to say how to do it.

[Brian Payne]

For you experts, do you see a difference between the M2 and the Vinci as to what power shells can be run through it? My Vinci won't run shells as light as the M2, but the M2 has thousands of rounds more through it.

For the Vinci I use the 3 Dram (1200 fps) 1 1/8 oz. green hull Remington STS as the lightest shells I will run through it to get 100% reliability. Anything under the 1200 fps limit tends to have a glitch here and there. I don't think I have over 1000 rounds through the Vinci though.

[P.E. Kelley]

I think that is one of the reasons you see Vinci's with the "speed bolt" feature. More carrier (bolt body) weight (mass) the better for the lighter loads.

[openclassterror]

I have a theory that the reason the Stoeger m3000 inertia gun is so forgiving load-wise is the carrier extends forward around the mag-tube because the recoil spring is there instead of inside the stock. This adds mass to the "bolt group" (for lack of a proper term), which resists movement more efficiently than the bolt by itself. Because the assembly weighs more, it stays put longer, which compresses the inertia spring further before "un-springing" for any given load. Mine runs flawlessly with loads that stall Benellis consistently. Not enough of an engineer to claim factual truth, but it seems like the most reasonable explanation to me. I run a 13-shot tube AND a ported barrel, and no cycling issues with light loads, even if I start with a 15 shell ghost load. I swear it loses HALF its weight by the time it is empty!

How light of loads are you talking? I can run 1145fps 1 1/8 oz in my M2. If love to be able to shoot some 980's in the shoot off.

I haven't tried low velocity 1-1/8oz, but it cycles without fail at 1oz 1100fps loads. Even with the crappy Winchester hulls

[dchang0]

@Brian Payne--

Are you having the problem where the Vinci short-strokes and does one of these two things:

1) Attempts to eject the empty hull too soon, catching the mouth of the hull on the front of the ejection port.

2) Ejects hull at proper time, but lifter fails to lift the next live round into the chamber.

If so, you need the Speed Bolt just like me. I have been trying to get a live person on the line at Benelli for a few weeks now to give them my money for a Speed Bolt, but so far no luck.

[Brian Payne]

dchang0,

Yep on #2, it has happened twice. The lowest power shell I will use in a match is the STS 1 1/8 oz 1200 fps stuff so it really isn't a big deal. I had tried some lighter stuff in practice once and found out the shotgun didn't like it. For some reason up here in MN I can find cases of the STS 1300 fps gold hull stuff very easily and that runs through this shotgun 100% and this is what I plan on using for next year. I will keep an eye on threads regarding the speed bolt, but I am in no hurry to change.

[CJW]

I haven't tried low velocity 1-1/8oz, but it cycles without fail at 1oz 1100fps loads. Even with the crappy Winchester hulls

Now, that's really strange—those are the same specs as the Fiocchi slugs you said, in the other thread, that your gun doesn't like. Odd...

[openclassterror]

I haven't tried low velocity 1-1/8oz, but it cycles without fail at 1oz 1100fps loads. Even with the crappy Winchester hulls

Now, that's really strange—those are the same specs as the Fiocchi slugs you said, in the other thread, that your gun doesn't like. Odd...

As I said in the other thread, I have never been able to find the Fiocchi 1oz slugs. The low recoil Fiocchi's I tried are the 7/8 aero slugs at 1300fps. I have had only one FTF with ANY 1oz load of any kind, and that was my fault for not cleaning it thoroughly after I did some work on it. I know the manual says to use 1-1/8 or better, so I am not saying they all work with 1oz loads, but I am not seeing the oddness of my answer. Perhaps you misread my other post?

Edit- I must add that I have not done a definitive study on the Fiocchi 7/8oz slugs. I shot only 5, and at that point the shotgun had only about 100rds through it. So in order to make sure my remarks are not interpreted as a hard and fast rule, I am only relaying my personal experience in a very limited test. I know they theoretically produce more energy than the 1oz Aeros, but as I have not tried those in my gun I cannot say if they work better or not. The only low recoil slugs I have shot enough of to confidently say I trust are the Speer managed recoil Lawman slugs, which I was able to buy a quantity of. All the others I tried functioned with no failures, but I don't think I have shot more than maybe 25 of any other brand of low recoil slugs. As I stated, in our neck of the woods slugs have been in short supply for quite some time. I am not trying to present myself as a guru of the Stoeger platform, I am just trying to relay what experiences I have had with mine.

Tom

Edited December 13, 2013 by openclassterror

[CJW]

Perhaps you misread my other post

I was, apparently, insufficiently caffeinated when I was reading and writing yesterday... Sorry.

The fact, though, is that 1oz @ 1100fps is, as you point out, significantly lower muzzle energy (more than 150 ft*lb) than is produced by the 7/8oz Fiocchi slugs that you've had issues with. That is what seems odd, because energy should be the only determinant in cycling an inertia system like this. I realize that the M3000 is a different gun, but when I have watched people run LR slugs through Benelli M2s, they all ran the 7/8oz Fiocchis and most choked consistently on the 1oz @ 1100fps slugs.

Do you know what the specs were on the other LR slugs you have been running successfully?

[openclassterror]

Low Recoil-

Speer Lawman- 1oz at 1200

Remington Slugger- 1oz at 1200

Winchester Ranger- 1oz at 1200

Fiocchi Aero- 7/8 oz at 1300

Full power used-

Winchester Super X Max dr.eq. 1oz (no vel listed, OLD box!)

Remington Slugger- 1oz at 1560 (ow!)

Couple others of which I didn't keep info.

No Failures except 2 of 5 Aeros failed to load subsequent round. All 5 ejected successfully though.

[openclassterror]

Another note on something that affects inertia guns- size/ mass of the shooter. I am 6'3" and about 250. My 11 yr old son is 5'2" and only about 120. He cannot get my inertia gun to cycle reliably at all, even with 1-1/4 hi base stuff. Many instances of empty chamber/ failure to load malf's. His stance is poor, as he has to lean back a ways to keep the 13 shot tube from tipping him over on his nose. He has no trouble with my short 1100 gas gun cycling, but he doesn't hafta play counterbalance either. . So, there are some other factors that play into reliability experiences with this type of action. You can't prevent the gun from moving, but you can't let it move too much either. Might help explain why some loads work for some and not others.

Tom

[dchang0]

I am running the Fiocchi 12ga 1150fps 1oz low recoil slug through my Vinci. It appears to cycle better when shooting offhand (shotgun can move with the shoulder) and goes single-shot due to short-stroking when the shotgun is braced on a barricade.

Sadly, bracing on a barricade is practically a requirement for these long slug shots we are expected to make at X3's monthly match.

I had been using B&P's old 1200fps 1oz low recoil slug (now no longer in production), but those short stroke even when shot offhand.

I called Benelli and they were kind enough to give me the part number for the PARTIAL Speed Bolt assembly, but finding someone in the distribution channel who will special order it from Benelli has been tough so far. MidwayUSA and Midwest Gun Works have both refused to order it. I am waiting on Numrich and Brownells to get back to me after SHOT.

Numrich's price list seems to indicate the PARTIAL Speed Bolt assembly will be around $555 because that's the price for the non-Speed Bolt partial assembly. I emphasize the word partial because they also list the complete bolt assembly as a purchasable part number.

The part number given to me for the partial Speed Bolt assembly is 10595. If somebody figures out how to get these ordered, please let us know!

[dchang0]

energy should be the only determinant in cycling an inertia system like this.

Almost……..

Energy plays a part, but so does momentum. Inertia is actually momentum. The difference does have real-world consequences when it comes to cycling/functioning and of course ballistics.

[dchang0]

I think that is one of the reasons you see Vinci's with the "speed bolt" feature. More carrier (bolt body) weight (mass) the better for the lighter loads.

I'm wondering if I can approximate the qualities of a Speed Bolt by buying a lighter inertia spring.

Hooke's law says that the potential energy of a spring is 0.5kx^2, so when comparing two springs, for a small linear decrease in k, the spring constant, the energy stored is greater due to the squaring of the distance displaced (delta-x).

Good luck finding a lighter inertia spring, though… I guess kurtm found a way...

[Jesse Tischauser]

I think that is one of the reasons you see Vinci's with the "speed bolt" feature. More carrier (bolt body) weight (mass) the better for the lighter loads.

I'm wondering if I can approximate the qualities of a Speed Bolt by buying a lighter inertia spring.

Hooke's law says that the potential energy of a spring is 0.5kx^2, so when comparing two springs, for a small linear decrease in k, the spring constant, the energy stored is greater due to the squaring of the distance displaced (delta-x).

Good luck finding a lighter inertia spring, though I guess kurtm found a way...

Whoa it just got nerdy in here! I'd love to be able to run those low recoil lie noise shells in a Benelli.