HAUS A5 BARREL INSTALLATION PROCEDURE

THE SET UP

Your set up is important, the goal is to have zero flex in your table or workbench.

If your table or work bench is flexing brace it up from underneath until it feels solid.

When you eliminate the flex from your mounting surface the results are dramatic and torquing these barrels down is quick and easy.

On the other hand if you have a poor set up with a lot of flex you’re going to struggle and maybe even damage your barrel or receiver.

We use the Nefarious Arms barrel mandrel clamped in a vice that’s through bolted to a workbench, there’s vey little flex with this setup, through bolting your barrel mandrel directly to your work surface also works very well.

THE TOOLS

  • BENCH VICE – A forged bench vice with at least 5″ jaws

  • TORQUE WRENCH – 1/2 drive adjustable torque wrench

  • BARREL NUT WRENCH

  • ASSEMBLY GREASE

  • ELECTRIC HEAT GUN OR PROPANE TORCH

  • BARREL MANDREL – A barrel mandrel that can be installed in a vice or bolted to a work surface

 

 

THE PROCESS

  • Lubricate barrel nut threads

  • Place barrel nut on barrel making sure the threads are facing towards the receiver

  • Lubricate the inside of the receiver neck

  • Heat the receiver neck evenly with an electric heat gun for 1-2 minutes taking care not to melt the dust cover, a propane torch will also work if you’re confident in your abilities

  • Quickly work the barrel extension into the receiver before it cools by twisting back and forth while you press the tow parts together. (This is the only step that’s time sensitive, otherwise, work slow and carefully)

  • Align the notch in the extension with the tap on the barrel, be thorough, YOU WILL NOT BE ABLE TO DO THIS LATER

  • Gently tap the barrel with a dead-blow until the tab and notch mesh and you’re able to see the gap closing, once you’ve closed the enough to start threading the barrel nut on move to the next step

  • Thread on the barrel nut and finish mating the barrel and receiver by slowly tightening the barrel nut

  • Once you feel the barrel and receiver mate up loosen the barrel nut and check to be sure the barrel is completely seated in the receiver

  • Thread the barrel nut on, torque it  to 81ft. lbs, then back off the nut until you can turn it by hand, do this twice then torque it down a third and final time to complete the installation.

  • Barrel nut torque spec. – 110 Nm +/- 10Nm or  81 ft. lbs+/- 7ft. lbs

THE WHY

We designed our extensions to fit very snug in genuine Heckler & Koch upper receivers, hence the need for a heat gun or propane torch.

THE DISCLAIMER

Haus Manufacturing LLC does not provide gunsmithing services, this is simply an example of our process for our own test rifles. Haus Manufacturing LLC is not responsible for damage to personal property or injury to individuals.

HK GMBH and HK USA have their own systems in place for this procedure, armorer’s classes are available, click the link for more information: https://hk-usa.com/training/

 

 

 

 

 

 

 

 

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