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Benelli M4 -- Weapon light mounting Options Suck!


StrangerDanger

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Basic apprenticeship type tasks. I only know the basics of lathe operation. My father is a machinist by trade, so I bought the lathe and set it up at his house as a gift. We don't live super close together, so it'll be a few months before we get together for a week or so. All the lathes at his work are huge. The smallest one has an 8' bed and a 12" chuck. So getting something on the smaller side should help a lot since most of the items produced are quite small.

 

He's already internally threading a bunch of parts.

 

I'd like to put together some receiver extensions for the Benelli M4 out of aluminum 7075 or maybe Titanium. I'd rather aluminum for weight savings. I'd like to add multiple positions for the collapsible stock to engage. I can do a few other cool things like extend the threads on the exterior so users can use those sling plate adapters with the collapsible stock. I can then hone polish the inner diameter of the extension for smooth operation. Then I can have them coated via a third party in Nickel Boron, and top coat them with black Cerakote.

 

Aluminum should be plenty strong for the extension. Aluminum extensions are used on the big bore AR15's without any issues. Titanium kind of limits your coating options, plus it's heavier than aluminum. Weight savings isn't that important due where the extension is located, but cumulatively, weight drops are important.

 

I need a mill to finish this up though.

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I gave that a roll awhile back. It came in the view of the sights, but just barely. I am not sure I liked the balance 100% either.

 

Love the idea of a aluminium receiver extension with mounting options SD.

 

Given FFT and CC out there, I am surprised there aren't more custom parts out there for the M4. Better mounting options and sling attachments are sorely needed.

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Maybe when I get my trust set up. :)

Monocore's look really interesting. Far better than the old baffle designs.

 

Few people are willing to go through the trouble to remove the receiver extension. It's a hard job, much harder than the magazine tubes people are breaking loose these days.

Edited by StrangerDanger
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I agree. I've done like four of them and found it to be pretty straight forward. And I'm the type that hates changing my own oil.

 

Another item I want to experiment with is lighter weight recoil plungers. I'm always chasing a faster action in the M4 so I can quit outrunning the action on double taps.

 

I might try to make an aluminum magazine tube to see how resilient it is. They might be of value to competition shooters. They'd be lighter than even the titanium units.

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Sucks. I keep forgetting to place an order with them for those damn cups.

 

i spent about an hour and a half last night tweaking my handguards. I stripped the rubberized paint off and worked on sanding the mount area with various grits of sand paper and a sanding block. It really smoothed out the edges and profiled the hump quite nicely.

 

I touched bases with Controlled Chaos, and planned to send the handguards in for Cerakoting. The handguards will be painted Graphite Black inside and out to mask my work area. Then, they are going to paint the recessed vertical grooves Burnt Bronze. I figured that would break up the black some.

 

I'm sending the plastic pistol grip core to be painted Burnt bronze. The magazine cap and the cheek rest of the collapsible stock are being sent as well. I am having them painted graphite black so they match the handguards. For cosmetics, I opted to send the rear handguard hanger to be painted in burnt Bronze.

 

Theyre painting two more Aimpoints for me like the others. I am also sending the small plastic plates that go on the very back of the Surefire X300 Ultra between the rocker switch to be painted in burnt Bronze.

 

I disassembled four Troy Industries flip up iron sights and sent the bases along with the mounting nut to be painted burnt Bronze. I left the flip up portion black to go with the two toned look. Plus you canno disassemble the rear sights aperture, so that would be a nightmare to tape. The sights come apart a lot easier than I expected. I was surprised to find that the front and rear sight housing is identical. Only the flipping portion is different.

 

I'm sending my 9mm AR15's PWS pistol receiver extension to have it painted in Burnt Bronze. I finally found a way to peal the foam cheek rest off without damaging the foam. I thought it was glued on.

Edited by StrangerDanger
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It's not bad, I did this to my aug in the aug's mag well. I also have one up front on my mod'd blam4 on my sbs m4.

 

If I was committed to doing so, I would explore if it could be done closer to the receiver.

 

For a two point the stock works great. I desire a fixed point on the receiver or top of PG so it holds the system where I want it for a single point as well.

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A mount there is strong enough for civilian work. My concern is how the QD socket would feel with your face there. Or how the sling will bunch up at your face.

 

What might work is putting the socket on the right side of the cheek rest. That way the whole left side profile is left alone. I usually connect my QD socket to the right side of my Ar15's in the back (right hand carry method.) this limits how much the rifle hangs away from my body. It also allows for more range of motion.

 

This is theory for the m4 though, how it hangs and feels could be quite different and difficult to mock up prior to drilling into a part that is nearly impossible to replace.

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Thanks -- I'm trying to decide if I'd be better off with the IWC stock sling loop mount made for the CTR stock or doing a QD IWC dock in the C-Stock plastic riser. I run a 2-point sling. Its tough to mockup right now as my 14" M4 has been sitting at the CL3 dealer for a long time awaiting my stamp (# 11724 bought back in early November). I ran the mesa rear QD dock in the C-stock grip area on my last M4 and it drove me crazy stuck into my chest! I now prefer the rear dock farther back.

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The QD socket for the CTR is probably the best route to go since isn't a permenant modification. It will be stronger than the cheek riser mount option too. You can easily flip the CTR one to try the connector on both sides to see which way works the best.

 

Using this mount with the modified BLAM4 mount would work great for a 2 point sling.

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That height measurement might not be correct. The male portion of the swivel is like 0.350" long itself. That 0.688" figure sounds like the rim measurement. Figure the body is 0.500", that leaves 0.188" difference, or 0.094" height difference from the body.

 

Removing that much material wouldn't be that hard. Or, the hole could be enlarged to the 0.688" spec, then back-filled with epoxy. The only real problem with this is drill bits larger than 0.500" are somewhat pricey and sometimes difficult to find. Most sets only go up to 0.500".

 

Finding a 11/16" drill bit would be a PITA. At this size, the hole would be touching the raised up shelf of the grip.

 

Also, I noticed with my dual QD setup, I essentially made my VCAS padded sling a single point sling by connecting one QD connector to each side. Sadly, it'll be about six weeks before I find out if it works in the field or not since the bulk of the shotgun is off at WMD Guns.

 

Good news / Bad News.

 

I got the IWC unit in the mail today.

 

I don't think it's going to work unless you're going to turn the entire thing in a lathe, not just the rim.

 

The rim measures .739" diameter.

 

The cup measures .627" diameter.

 

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Fat little piggy.

 

I think my best option is the ace cup, it has the most ideal dimensions that I know of for a countersunk mount to the PG. It will lack anti-rotation though.

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Of course, could just drill 5/8in. Re-measures put it at about .625, cheap calipers.

 

Still need to turn it down. I wonder what type of drill bit would be the best for the job, probably have to order one unless I use a spade bit - the only 5/8 bit I likely have.

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This sucks. How tall is the mount with and without those feet.

 

Any machine shops near you? Turning the whole thing down to a specific diameter on a lathe would be easy. If the lathe was at my house or nearby, I'd offer to turn yours down. Drilling out to 5/8 is going to be a really big hole. You'll be drilling through that raised shelf above the existing hole.

 

You could probably do the drilling with a wood boring bit due to the soft plastic. Your spade bit would probably work as well though. Just be careful going through into the opposite side with the pilot.

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This sucks. How tall is the mount with and without those feet.

 

Any machine shops near you? Turning the whole thing down to a specific diameter on a lathe would be easy. If the lathe was at my house or nearby, I'd offer to turn yours down. Drilling out to 5/8 is going to be a really big hole. You'll be drilling through that raised shelf above the existing hole.

 

You could probably do the drilling with a wood boring bit due to the soft plastic. Your spade bit would probably work as well though. Just be careful going through into the opposite side with the pilot.

 

Without the feet it is .515" tall.

 

With feet it is .615" tall.

 

My ace cup is right at .5" tall.

 

I agree not only would the IWC cup intrude on the chamfered shelf above, but the chamfered geometry in front of it as well, unless turned down.

 

Going to give it some more thought. If I had to do it right now, I'd do the ace.

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You could build a poor mans lathe with a drill and just use a 'fatherless child' file to profile the OD down to 0.500".

 

It doesn't have to be super precise. I'd probably epoxy the cup into the pistol grip to prevent rotation. Are you still planning to tap the plate retainer? I was thinking it might be best to drill into the plate retainer so the cup seats lower. You could probably get a flush fit doing that.

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I will have to pull the PG off again and measure the nut retainer in there. I believe the last time I looked at it I had concerns about countersinking it to make even the ACE cup flush due to how thin it was and how little the cup would protrude anyway.

 

If the IWC was turned down in a drill with a file my concern would be smooth edges, finish, and properly maintaining center. Amplified if it cannot be fully flush since all of that would be exposed. Hitting just that ledge on the bottom I had no such concerns with a drill, but having to reduce the entire OD changes things.

 

I have more confidence in the ACE at this point - no machining, smoothing or refinishing required. Only downside is no rotation limitations. I might be able to solve that problem easier than the problems with the IWC with some epoxy. Fill the groove in the socket, use a small bit to mill out epoxy in spots similar to the pockets in the IWC Rotation Limited QD if you cannot live without them. I have a Magpul socket I can test this theory on.

Edited by bm4sbs
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Making your own limited rotation stops would be difficult. I'd use JB Weld. I'm not sure how long it would hold up though. The torsional force exerted by the QD connector is pretty high.

 

I think you could hit the external edge with a file while rotating it and bevel the edge quite easily. I believe the cups are steel, right? You could hit them with some of that instant bluing after doing the filing.

 

I looked at the grip core, if you grind off the feet and have a .510" overall length, seated up against the plate retainer will have approximately .200 exposed out of the grip. Roughly what I have now with the left side connector. If you were going to drill out the plate retainer, you'd have to go into it about .200", or approximately half way through the part. Then thread the remaining portion, and protrude into the opposite side for retention of the plate.

 

Drilling out that part would not be fun. Mainly since the bottom of most bits are not flat. So you'd end up with something other than a flat bottom to seat the cup against. I don't think it's worth the headaches involved. .200" exposed is pretty good. It is certainly much shorter than the Mesa Tactical option. On the lathe, this would work out well, since you could leave a lip on it. Doing it by hand with a drill would be harder, but still possible.

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