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Installing a Limbsaver 10403 on a Benelli M4 Collapsible Stock


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Finally an easier solution for adding a Limbsaver to the Benelli M4 is available. This is significantly easier and requires fewer parts in the past assemblies of the 10111 model that required the Noveske adapter plate that is no longer sold.

For this assembly we'll be using the Limbsaver 10403. This model has a raised lip on the inside of the buttpad that helps center the pad on the stock.

First step is to remove the collapsible stock from your shotgun. You will then need to remove the factory buttpad by using a philips screw driver and inserting it in to the two small holes on the factory buttpad. Use a little oil or spit on the driver to help push it in. Push the driver in firmly as you unscrew the fasteners. Pull the buttpad away from the stock as you unscrew it. The screws will remain captive inside of the buttpad.

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Not the large hole roughly in the center of the stock. This is where the receiver extension passes thru the stock and in to the buttpad when the stock is in the fully collapsed position.

 

The next step is to fit your buttpad to the stock. I had to purchase screws from the hardware store to make this buttpad work for this application. I used M4 machine screws, 0.7 thread pitch, 16mm in length. You will need two of them. The ones I bought use a 2.5mm allen head driver. Press the screws in to the Limbsaver buttpad through the two holes in the rubber. Use your driver to press since it will have to push past the rubber. They will snap in to place once seated. You'll see the threads sticking out of the bottom of the buttpad. Screw the buttpad on to the stock.

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Note the two holes top and bottom for accessing the screws.

Now we need to make a hole in the plastic base of the buttpad for the receiver extension to pass in to. Now that you have the pad attached to the stock, you'll want to get a Sharpie marker with the cap off and drop it down the hole of the collapsible stock where the receiver extension goes. I use a silver one since it makes it easier to see the marks. I shake the stock around a little to get the marker to give me a witness mark as to where I am going to drill.

Now remove the buttpad from the stock and check your witness marks. You should have something like this.

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You now know roughly where you  need to drill your 7/8" hole. Rather than trying to bore that big of a hole in one pass, you'll have better luck starting small and moving up. I start with a 1/4" Forester bit and drill it out on a drill press. You do not want to drill all the way through the buttpad. You only want to drill through the plastic back which will open up to a void inside the buttpad. I suppose you could drill this out with a electric drill, but your quality of work is likely going to suffer.

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First hole is drilled. Take the pad and offer it back up to the stock. Look down the hole where the receiver extension goes down with a flash light and see how close to center your hole is to the hole you're looking down.

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I see that I'm a little off center to the right of the screen. No problem. Move to the next size up bit 3/8" and try to correct for the alignment. Continue through the 1/2, 5/8 and finally the 7/8 bit. Here is the end results.

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Clean out all the plastic debris from inside the buttpad and clean up the edges. I use a deburring tool but you don't have to get that fancy. Offer the buttpad up to the stock again and check to see if you can see the sides of the buttpad through the hole. You should be looking straight in to the hole drilled. If an edge is present, it will liely contact the receiver extension and prevent it from collapsing. You can hog out the hole slightly with no ill effects on performance. Finally offer up the stock with the buttpad screwed in place to the shotgun and see if the stock fully collapses. If it hangs up, you need to remove the offending area. If it fits, finalize the installation by applying some blue Loctite 243 to the screws then snug them up. No retard strength is needed. These threaded holes will strip easily if you muscle it. Use your fingers to hole the buttpad in alignment to the stock as you tighten it. There is a small amount of wiggle room in the pad that will allow you to even out the alignment. Make sure everything still fits after you've tightened the screws.

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The rubber of the Limbsaver will often times have a dried out look to it. You can rub some lubricant on the rubber with a rag and it will return it to a deep black finish.

Limbsaver claims you'll see a 70% reduction in perceived recoil with these pads. That figure is a little optimistic. Realistically I'd say you'll see a 40% reduction.

 

 

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Agreed that the factory pad is pretty stiff and unforgiving. We had one M4 with the factory buttpad and one M4 with the Limbsaver installed to test. Within a couple dozen rounds, no one wanted to shoot the M4 with the factory buttpad anymore.

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  • 4 months later...
Posted (edited)
7 hours ago, aznwhip said:

@StrangerDanger Do you know if the factory screw is loctited or something? Having a hell of a time unscrewing it and worried about stripping the head. 

No, it should not have loctite on it. Do you have the right sized screwdriver head for the bolt in there? 
Just turn slow while pushing firmly on the screwdriver then it should come right out. 

Edited by ClackClackBAM
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2 hours ago, ClackClackBAM said:

This is very helpful!
Now that I can see the process, I realize it's not as involved as I thought.
I will get a forstner bit if necessary, but @StrangerDanger can a paddle bit be used with a battery drill?

That's a good question because if one doesn't have the bits or a router set they aren't cheap.  Especially if you are using a bit for a one time job.  I wonder if a 7/8" hole saw would give reasonable results.  Maybe not quite as clean.

The sharpie method looks good.  Rosin or baby powder might give a good representation as well if applied to the end of the recoil tube?

 

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2 hours ago, Milspec said:

 

A guy could probably steal some of his wife’s old lipstick and lightly coat the recoil tube end, install the buttolate and collapse it allowing the lipstick to transfer to the pad.

 

clean up is easy using gun solvent, alcohol or any other solvent

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16 hours ago, ClackClackBAM said:

No, it should not have loctite on it. Do you have the right sized screwdriver head for the bolt in there? 
Just turn slow while pushing firmly on the screwdriver then it should come right out. 

Thanks, that was it. I was trying to get cute with my Wiha PH1 screwdriver, but should have just rammed a full size screwdriver in there

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Those paddle bits are going to try to walk on you in a hand drill. The Forester bit will do the same, but not as bad. You might have better luck with the hole saw bit since it drills the center hole out first to hold the bit centered. 
 

Even putting grease on the end of the receiver extension should transfer to the buttpad fairly well. I find the Sharpie to be the easiest though. 
 

Seems you got the philips bit sorted. You definitely don’t want to use a magnabit type driver. It’ll get stuck in the rubber hole. 

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On 7/2/2020 at 11:36 AM, StrangerDanger said:

Those paddle bits are going to try to walk on you in a hand drill. The Forester bit will do the same, but not as bad. You might have better luck with the hole saw bit since it drills the center hole out first to hold the bit centered. 
 

Even putting grease on the end of the receiver extension should transfer to the buttpad fairly well. I find the Sharpie to be the easiest though. 
 

Seems you got the philips bit sorted. You definitely don’t want to use a magnabit type driver. It’ll get stuck in the rubber hole. 

I was afraid of that. Eh, I guess I'll just splurge on a set of Forester bits then. 

12 hours ago, Vertigofirearms said:

Has anyone installed the Limbsaver AirTech Precision-fit pad yet?

Unfortunately there is not an AirTech pad that will fit the collapsible stock. 
It will, however, fit on the standard and field stocks. 

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50 minutes ago, Vertigofirearms said:

Do you know which number fits the regular stock?

 

Yes. It's 10180. 
If you're going to buy one, don't go spend $40+ tax. I have a brand new one that I bought thinking it would fit the c-stock, only to find out it does not.
Shoot me a PM if you decide to go that route then I'll be able to save you some cash.
 

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Okay, cool. PM me then we'll work it out.

Well this is an issue with any limbsaver pad, unfortunately. To get the c-stock fully collapsed you need to drill out a 7/8" hole through the plastic pad. I wouldn't recommend doing that with an AirTech though, as you're going to rupture the air cavity that provides the cushion and reduce its effectiveness. Also, the Airtech pad is larger than the c-stock so it would hang off each side by almost a 1/4". 

If you want to put a limbsaver pad on the c-stock, you/ll need pad #10403. 

 

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So it doesn't fit the profile perfect? I am looking for the Limbsaver Airtech with the closest matching profile to the original. It wouldn't be for a collapsible stock. I am thinking of putting it in my field stock. I did just spend close to $170 on a different pad for a different project. Maybe I will just use that one.

How does the Airtech compare to the old? I am assuming you have both now.

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Posted (edited)

Well the Airtech 10180 will be a perfect fit for your pistol grip or field stock. It just won't fit on the collapsable stock.
*edit- also, there isn't an Airtech pad that fits the collapsable stock. You need the original Limbsaver like Stranger has pictured at the top of this thread. 

Edited by ClackClackBAM
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