Benelli M4 -- Loading Port Modifications

Today's project was to modify my 11707 M4's loading port. I had watched several users do similar modifications on the M2 platform for 3 gun competitions. I figured it would be something that would port over to the M4 well.

After doing a bit of layout with blue painter's tape, I went to work with a large flat file. I removed about 0.25" of material from the bottom of the loading port. A large flat file spanning both sides of the port helps to keep a nice flat even cut.

After working the surface down, I beveled the edges with the file, then switched to a dreaded Dremel with several sizes of sanding bits. I opened up the inner port by removing material at a steep angle towards the rails the bolt carrier rides in. I then opened up the front mouth of the loading port a little.

I then used several grades of sandpaper to knock down the edges of the compound cuts.

Now, there are no sharp edges anywhere within the loading port.

When combined with the TTI elevator, this makes for a really nice loading port for speed loading. I can't say it's a night and day difference, but you definitely have more room to get your thumb inside.

Here, the modified areas were coated in Alumablack.

Visualization of how much material was removed.

You got balls as big as Pickle Jars my friend!

Walking around with them sure is tough!

Walking around with them sure is tough!

Yeah but everyone clears a path when they hear that clank!

Damn Son.

That is wicked.

Thanks.

This receiver is going to Robar to get turned into a H20+. So I wanted to get the modifications done before sending it out. I do like how all the edges were beveled off. I think I did a pretty good job at putting the gradient slope into the transition. The main area removed is perfectly flat.

dang......

what is that one little hole for that got partially removed? looks great, if someone dares me,,,,,,,

That's the access port for the pin that holds the shell stop.

Bravo! Nice work. If there is anything that I can think of to improve the M4, it's removing the sharp edges surrounding the loading port.

When I first got mine, I was messing up the skin on my thumb on those edges until I got used to it and perfected my technique. Now I live with it.

Mine is an H2O model so doing what you did to yours in not on the table for me, but even if it were a parked receiver, I don't think I'd have the guts to go at it with a file.

I would have a machinist with a mill radius the edges off but no filing for me! Nice work!

Thank you. The first pass of the file is the hardest one to do -- intentionally damaging the finish of an expensive weapon. I considered waiting until I got a mill, but figured the hand file would be slower and a little more controlled. With a decent file that is cleaned every minute or two, it cuts pretty evenly. A couple layout lines and you have a solid visual reference to where you need to remove material. Polishing bits on the dremel work well along with sanding by hand with various grits of sandpaper.

This M4 will eventually get sent to Robar to get turned into an H2O+ model. I have weighed if I want to do this modification to my burnt bronze/nickel boron M4. I'm leaning towards no since I don't want to mess up its finish.

Thank you. The first pass of the file is the hardest one to do -- intentionally damaging the finish of an expensive weapon. I considered waiting until I got a mill, but figured the hand file would be slower and a little more controlled. With a decent file that is cleaned every minute or two, it cuts pretty evenly. A couple layout lines and you have a solid visual reference to where you need to remove material. Polishing bits on the dremel work well along with sanding by hand with various grits of sandpaper.

 

This M4 will eventually get sent to Robar to get turned into an H2O+ model. I have weighed if I want to do this modification to my burnt bronze/nickel boron M4. I'm leaning towards no since I don't want to mess up its finish.

Any chance of re-uploading the pics?

There is another thread that is similar to this one.

Mike