RP46 heavy barrel

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RP46 heavy barrel

RP46 heavy barrel


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Please read ENTIRE description BEFORE you purchase!  Purchases made in error will NOT be refunded once shipped!

A description with notes followed by purchase options.

As with the RP46 belt feeder, we have made some improvements to the system that we hope you will find useful.  They are as follows:

First, the gas adjustment system:  the original was a plug with the different size slots cut on two sides and a spring locator tang to hold the gas selection.  This worked but required the user to adjust the system by using a hammer or mallet to switch between 2 of the settings and to remove it completely and install it from the opposite side to get the 3rd setting.  This seamed a bit archaic and so we changed it radically. We basically copied the RPD selector.  The adjuster has a bolt on one side that you loosen until you can tap or push the selector out far enough to clear the locator pin, rotate it tot the desired position, push it back in to engage the pin and re-tighten the bolt.  You still get the 3 levels of gas adjustment.

Second, the piston setup: The original piston replaced the DPM rod completely where it threads into the carrier.  It slid into a tube on the gas block like an AK.  We went with a piston tappet design like with an M60.  The reason for this, was the original piston had a LOT of clearance inside the tube on the gas block and in order to get enough gas pressure to operate our semi-auto, the fit between these parts had to be made so close that if there was ANY mis-alignment between the gas block and gas tube on the shroud, it would either give too much drag to overcome or would strike the face of the tube during return.  The tappet style piston allows for a little bit of mis-alignment, while also giving the gas pressure needed to reliably cycle the system.

Third, the piston rod itself.  We've made a replacement rod that takes the place of the rod installed on your DPM/DP-28 carrier.  It will come with two ends.  One is the push rod end for the RP46 heavy barrel and the other is a cup type piston so that you can use your original DPM/DP-28 barrels again by simply changing tips and barrels.  They have wrench flats and are held in place by a lock washer installed between the tips and the gas rod end.

The use of the heavy barrel and improved gas system will allow you to use multiple bullet weights, better belt pull, cleaner action, no booster & a barrel that can take longer use without overheating.

The barrels themselves, we are having made by the same outfit that is making our DP series barrels.  They are brand new US made to the original barrels specs.  Chrome lined.  If you have a gas block for one of these, yours may or may not press on without some minor polishing. 

All other parts listed below are being machined in house by SMG.

Although this barrel WILL fit inside unmodified DPM and DP28 barrel shrouds and lock-up and headspace the same as the factory barrel, A DPM OR DP28 GAS BLOCK WILL NOT FIT/GO ON AT ALL.

On a DPM, it may be necessary to cut the ends of the bipod leg pivot/mounting screws to allow enough clearance for the barrel to be inserted.  Also, if you have the RP46 top cover installed, you may have to pinch the front latches together while inserting the barrel to give clearance for installation only.

Purchase option: Please choose the desired option from the drop-down menu.

Option1)  In-the-white barrel only:  choose this if you have your own gas block and associated components to make your system work.  Barrel will ship as it comes from the barrel maker.

Option 2) Blued barrel with Gas block, tappet, and adjustment selector: If you already have purchased the full kit (Option 4 or 5) and just want a spare barrel to swap out when your first one gets hot.  This option DOES NOT come with another flash cone!

Option 3) Blued barrel with Gas block, tappet, and adjustment selector and Flash cone:  Same as option 2 but includes a spare flash cone so that you do not have to change the hot flash cone from barrel to barrel during a swap.

Option 4) Blued barrel with Gas block, tappet, adjustment selector, pistons tips, rod & new hammer: The complete kit, minus the flash cone. Comes with all parts mentioned in option description before colon. This kit will enable you to change out the gas piston rod on your DPM, or DP28 and then, just by changing the piston tip, go between your original DP barrel and gas system or the RP46 heavy barrel and adjustable gas system.  This option DOES NOT include the flash cone.

Option 5) Blued barrel with Gas block, tappet, adjustment selector, pistons tips, rod, new hammer & flash cone: Includes everything from option 4 but also includes a new flash cone.

If you are buying any of the above options with our gas block setup, you will need at least one "option 4" or "option 5" so that you can replace the gas piston setup on your DP.  THE ORIGINAL RP46 GAS PISTON WILL NOT WORK FOR THESE!!!

Downloadable instructions under the "Documentation" tab above.

New product


RP-46 Heavy Barrel Instructions

Barrel and gas system adjustments and installation

Download (1.26M)

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