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Rail came off!


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I have a Benelli M4 that has been a dream to shoot. Utterly reliable.....amazingly accurate. Love it.


Today, however, I had a major malfunction.


My Picatinny rail flew off the gun during shooting (I had an Aimpoint on the rail)! Worse, several of the receiver screw holes are stripped.


The rangemaster (who is also a gun smith) said this is not at all surprising considering the recoil of the shotgun. He sees it fairly often.


I am considering going to a gunsmith (or sending this back to Benelli) to have it retapped but I do worry about this happening again.


Does anyone know....it is possible to weld the rail onto the receiver or otherwise secure it securely? How secure is my Aimpoint/Rail combo going to be with retapping?

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If you re-tap the holes to a bigger size, use high strength lock tite, and make sure all the screws are TIGHT (make sure the gunsmith uses the proper torque, which with me being of german heritage and all, is guedin-tite, aka german torque) I don't think it will go anywhere, the gunsmith will be able to tell you.


This makes me wonder about having the heavy MESA 6shot on mine though.


Of course if ya quit butt-strokin people that would help a lot! :D



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Never did this on a benelli but ALL of my magnum cartridge rifles and handguns get their scope bases epoxied to the reciever or barrel depending on where the attach to the gun! A hopped up .500 S&W mag loaded to the gills kicks like a mule and is **** on scope mounts.....epoxy works great and can be removed with a plastic mallet if need be without damage to the gun!


Again this might not be an option on a benelli M4 but i'd never say never!

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Sadly, the Benelli shotguns have two strikes against them regarding optic rails:


1) The receivers are aluminum, and


2) There is very little material through which you can cut the threads.


This doesn't mean it is impossible to reliably mount optics or other accessories on the receivers, it's just that there is a greater likelihood of failure if everything isn't done right.


The most common problems are not torquing the screws enough (18 inch-lbs), something I am often guilty of myself as I am reluctant to torque too tightly and strip the aluminum threads. One way to mitigate this is if you are getting your receiver tapped for the first time or re-tapped, have STI (steel thread insert) taps cut so you can install steel Heli-Coils in the holes. Heli-Coils don't solve all your problems, but they do allow you to more reliably add and remove accessories and torque them down a bit tighter than spec.


We have had several customers install Heli-Coils in their Benellis and so far the results seem to be good.


In addition to getting the torque right, be sure to use blue Loctite on the threads.

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mesa, wouldn't more screws be a reasonable solution??? I have some heavy recoil custom encore barrels that have 6 and 8 screws in the bases....i still epoxy these but it only seems logical to add more to these benelli's......it will require some custom work and added expense but sure beats watching that rail fly across the room or range!

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I think the thread stripped because the screws had worked loose under repetitive recoil.

I wouldn't epoxy a mount to any gun.


If you properly clean and prep the two surfaces, the epoxy will not come off.

If you install it in such a way that a plastic mallet can break it loose, then you haven't created a proper bond between the surfaces anyway and it will more than likely release under recoil.


Blue loctite to the screws and the proper torque, along with a periodic inspection and check of torque is the solution.

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from my personal experience with epoxy mounted bases....YES, it does come off when both surfaces are properly cleaned with IPA and both surfaces are smooth....a rough surface is a whole other story!!!


Removal - you won't TAP it with a plastic mallet it takes a tremendous RAP with a mallet....enough that might damage some weak or wimpy aluminum rails....but I don't use aluminum rails I prefer steel and I use steel scope rings, too......maybe too heavy for those light aluminum tactical shotguns??? I have had aluminum scope rings shear in half from recoil....good reason to use steel rings, isn't it???


Heat gun does a good job removing epoxy, too without grinding or sanding just don't try this on plastic parts!


Blue Loctite isn't going to stand up to EXTREME recoil....seen that in many of my .454 Casull & .500 S&W handguns! How do you check and retighten with Blue Loctite, if it is loose it ain't holding is it???


BTW-if any of you are reloaders you know modern factory 3-1/2" ammo is for wussy's....real performance and real recoil comes from a custom load but ALWAYS keep them within the guns pressure limits!!!

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Blue Loctite isn't going to stand up to EXTREME recoil....seen that in many of my .454 Casull & .500 S&W handguns! How do you check and retighten with Blue Loctite, if it is loose it ain't holding is it???


We're talking about a M4 shotgun, which does not chamber 3.5" loads, not a .500 overcompensation hand cannon.


Simply put, the mounts came off because the screws stripped.


The screws/receiver stripped for one of two reasons:

Either they were over-tightened and stressed when originally installed or they were improperly installed and they worked loose and stripped under recoil.


The people who designed this combat-proven shotgun know all about torque and how much stress recoil puts on mounts. They designed it to handle these conditions, provided everything is properly installed.


Expoying a mount to a gun should be done under only one condition. That condition being that you don't want it to EVER come off.


If if can be removed by applying shearing forces with a plastic mallet, it is not TRULY epoxied to begin with.


Modern epoxies when properly applied to prepped surfaces will outhold the metals which they bond tegether. if you're getting it off with a plastic mallet, then you're not doing it right.


In response to how one is to check the mounts, it's pretty simple.

Periodically remove the optic and check the screws for proper torque. If you do find that a screw is working its way loose, remove it, inspect it and the receiver for signs of wear, and replace it.


Blue loctite is designed to keep screws from working loose under normal use. It works great on my mounts and I've never had it work loose, not once.


Of course, as with any such product, proper suface prep is crucial.

Most mounts and screws come with a coating of oil to protect them from rusting. All oil or grease should be removed before installation with loctite.


If you find that blue isn't holding, then you could step up to red, but that's still a long ways from epoxying the mount to the gun, properly or improperly.


Red loctite is less brittle than blue and it will therfore be less likely to break loose under recoil.

Be warned, however that red will require the application heat to remove, should you ever want to change the mounts.


Many BR shooters will also apply the loctite to the monuts themselves for an added measure of security.

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"not a .500 overcompensation hand cannon."


Hey 10Gauge, I think Tucker is talkin about your manhood! You gonna take that?!!


...... wait a second, the biggest hog leg I got is a .454! I am 66/100ths short! I must quickly get therapy for my insercurity issues and rush to the gun store to buy the biggest, baddest, most intimidating smoke pole known to man! (not neccessarly in that order, heII I think I will skip the therapy- to the gun store!) (That was for your amusement Mam- .... I meant SargeC)




Seriously though more power, if it can be shot accurately, is almost always better. .... and more fun!




"If you see me runnin- you had better catch up!"

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"tuck" means well....heck he has over 4000 posts on this site, he has a lot to say and I appreciate that. I never take anyones misguided comments personally either!


Second, I don't think "tuck's" an engineer cause he hasn't bored us with any data yet?!?! "Tuck" simply makes broad based statements about how 4 screws in a 300 win mag and blue locktite works so well it must be good for an M4 12 ga shotgun......ha, ha!


Like "tuck" said we are talking about a 12 gauge shotgun.....(for some reason "tuck" thinks I said an M4 was a 3-1/2", but I never said this in my posts......i said, "factory 3-1/2" loads were for wussy's"....never did I say an M4 was a 3-1/2" shotgun....totally out of context!)


anyway, lets look at some data on 3" recoil shall we?

(before we bad mouth my wimpy little .500 S&W or my "overcompensating" 10 ga Browning Gold)....


"tuck" thinks a 300 win mag has a lot of recoil.....fact is a 12 ga 3" (1-7/8oz - 1200fps) load in an 8 pound shotgun has more, over 2X the recoil energy!!!! 54 lb-ft. vs 25.9 lb-ft (180gr @ 2960fps in 8# rifle)....notice I am using a 3" load NOT a 3-1/2" load! I hope "tuck" doesn't think I'm saying an M4 weighs 8 pounds, I'm using this as a constant between the rifle and shotgun in determining recoil....please don't take this out of context in future replies!


since T-H mentioned his .454 Casull.......it has less recoil than the 3" 12 ga too....39lb-ft (300gr @ 1650fps in a 3.5 pound gun)......now if that .454 was a rifle (heavier) recoil would be significantly lower!


so what's my point.....it isn't rocket science that threads strip on an M4 rail!!

Let's review, per Mesa Tactical a thin aluminum reciever M4 with small diameter screws that tend to work loose due to recoil....the thin reciever may only be getting 2-3 threads per screw to hold the rail so I'm not surprised the screws strip out! Mesa also suggested steel heli-coils and that seems like a logical solution to the problem as well.


In closing, my comments about my own experiences with epoxy on hevi recoil handguns was based on actual problems where mounts and screws routinely come loose and the epoxy solved the problem. Lot's of people, other than myself, use epoxy on mounts...I didn't invent it! "tuck" would never use epoxy on anygun, perhaps he is opposed to epoxy bedding as well but that doesn't mean others do it and it WORKS.


case closed!

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Never mentioned 300 mag.

Yes, I have epoxy bedded several weapons, thus my comments regarding the futility of trying to remove properly applied epoxy.


Son, you've got a serious problem with my post count.

I'm gonna guess it stems from the same shortcomings that have led you to own those large bore firearms you claim to have.


Try not to let it bother you too much.

I'm sure you can catch up in a day or two, given your current rate of rapid-fire meaningless drivel.



I stand by my statements and I do not recommend that anyone use epoxy on their mounts unless they fully understand the potential ramifications.


As the professional gunsmith has already advised the gentleman, simply drilling them out and stepping up the size is a viable solution, but Brownell's also offers an oversized screw for exactly this sort of thing.

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looks like i found "tuckers" raw nerve......what took you so long???


my mistake on the 300 win mag I was certain you made mention to that somewhere but I have been wrong one other time this decade! Maybe you edited that out later???


you seem to enjoy reading my "drivel"....you have responded to nearly every post i made tonight!!!


was it the "data" comment that put you over the edge???


as I said in another thread....every forum needs a thread "nazi" and I think we know who it is at Benelli's!

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Just so you all know......when I got my shotgun I red loctited the rail down and torqued it to 25 pounds. I did not check the mount again for 1000 shells which was probably not good. The red loctite formed a sort of plug that just tore the screw threads out.


I also wonder if maybe I torqued the screws too much.....


I will probably call Benelli and see if they will fix. Any idea what the will say?


Also as an FYI......I mostly shoot low recoil slugs. I am still really surprised that this happened.


Thanks for all the good advice--just be nice to one another!

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I will probably call Benelli and see if they will fix. Any idea what the will say?


Benelli stands behind their products and they have one of the best CS departments in any industry. I'm not going to make promises, but there's good reason to have hope.


Yes, it would have been a good idea to check them periodically.


If Benelli can't help you then you might consider checking with Mesa via PM. I'll bet he's already got the fix worked out in his head ;)


As for the little spat, don't fret.

I know I'm no match for a true master of the Interwebs .


Tip: Don't click that link if you're subject to vertigo or are prone to seizures :cool:

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hey thanks for the plug "tuck" and the link to "myspace" page.......

you really are impressed with me aren't you????

your almost a stalker "tuck"....wow and a computer geek, too!


i have a hunt club website too! why didn't you post that?????

......then everyone could see those big bucks and gobblers we kill in ohio!


BTW - I shoot a Mathews bow if your still wondering.......


"tuck" you really work for benelli don't you??? a customer service weenie I'll bet!

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