Words and Pics: Rich Norman

Tip: treat it like someone else’s gun and you will install the heat shield faster.

Being too cautious leads to failure!

Those were the wise words Bismarck – HAO’s CEO – said to me when I confirmed the arrival of the final parts for my L119A2 IUR.

It was good advice because the heat shield is a massive pain in the arse to fit.

However, my 32mm crow’s foot wrench also arrived and I put that to good use first in nipping the barrel nut a bit tighter than my initial ‘hand tight’ effort.

The crow’s foot attaches to the torque wrench’s 1/2″ drive and then to the flats at the end of HAO’s barrel nut tool. Alternatively you can insert a lever through the holes in the end of the barrel nut tool, for some torque.

My upper receiver clamshell vice block doesn’t fit the IUR perfectly, but well enough for it to be held securely while barrel nut tightening took place. Naturally, during that time I had a barrel/hop group and cylinder inserted in the upper, as reinforcement against the clamping pressure of my Black & Decker Workmate (doubling as a vice).

Back to the heat shield and it goes into the front end of the IUR after the barrel is installed, but prior to gas block installation.

It’s bare on one side and lacquered on the other:

The retaining pins locate in two holes which previously seemed to have no purpose. Well, at least now I know what they’re for.

After installing the heat shield and then the gas block, I went about attaching the replaceable steel notch which was also included in HAO’s delivery. This is located where the charging handle latch bites into the receiver on a standard AR.

It slots into a pre-machined bracket and can be secured either using glue or by smashing a punch into the receiver so that it deforms around depressions in the notch piece.

I had a go at the punch method but 7075T6 is very tough stuff and my efforts pretty much bounced off, as I was wary of getting too caveman with it. So, in the end I used JB Weld.

The last thing I did was fully tighten the long screw which lives in the grenade lug. This intersects with the barrel nut, so would presumably stop it from coming loose over time.

Catch up on the full HAO IUR series here.

For more on the L119A2, check this out.

Also check out my interview with UKSF impression group E27 here.