Maple Ridge Armoury Match Nitride 5R 18.6" 308 barrel issues.

[Maple Ridge Armourer]

Keep us posted about this. MRA is getting a lot of bad press lately... Seems like they need to step up their QA on the barrels.

I got one of these in fluted SPR profile but have not mounted it yet. The gas port and extension pin line up and test fitting looked fine. Many others seemed to be fine too so I'm hoping yours is just one of the bad ones (out of almost 4,000 barrels made , according to MRA) that slipped through...

Two recent QA issues out of 300 barrels a month is not what I would consider a lot of bad press. This is less than 1%. I am sure your barrel is good to go but we are always here to back our products and support our customers. If you actually have any warranty issue please let us know and we will definitely make it right.

PS. One of the QA issues was resolved to the customers satisfaction and we are working on this one as you can see.

[Maple Ridge Armourer]

That extension looks like it is peeling....that is very concerning. I have yet to install mine and I believe MRA buys these extensions from a 3rd party....I sure hope this is not the norm.

1 case out of just under 4000 is not what I would call "the norm"

[Maple Ridge Armourer]

Nitride finish would be better IF they are smooth and free of tool marks and burrs.

There are no burrs and all critical surfaces are properly ground after heat treat and free of any machining marks.

[Maple Ridge Armourer]

Interesting... So the force might've been too much for the pin to handle and it broke loose?

Not likely, the barrel nut is torqued on at 140 ft-lb and the pin is made from HTSR steel and hammered into place, it is very hard.

The barrel nut being twisted on to 45 ft-lbs is only squeezing the barrel extension into the receiver and not rotating the barrel or barrel nut.

Now this could have occurred if the barrel nut was not sufficiently tightened and then a muzzle device was torqued on thus twisting the barrel inside of the receiver causing the pin to pull into the softer 7075 or 6061 alloy receiver. This in turn could have pulled the pin free of the barrel extension hole since at this point the pin would have had lateral and pulling force applied to it by the receiver.

[Bonjour43ma]

I appreciate the detailed explanations.

[mileageman]

Not likely, the barrel nut is torqued on at 140 ft-lb and the pin is made from HTSR steel and hammered into place, it is very hard.

The barrel nut being twisted on to 45 ft-lbs is only squeezing the barrel extension into the receiver and not rotating the barrel or barrel nut.

Now this could have occurred if the barrel nut was not sufficiently tightened and then a muzzle device was torqued on thus twisting the barrel inside of the receiver causing the pin to pull into the softer 7075 or 6061 alloy receiver. This in turn could have pulled the pin free of the barrel extension hole since at this point the pin would have had lateral and pulling force applied to it by the receiver.

Ah I think you need to change barrel nut to barrel extension in a few places in that post.

And depending on how you hold the lower while torquing the barrel nut will determine how much pressure is put on the index pin. For example using a Geissele reaction rod vs using a vise block that just holds the upper receiver.

[jiffx2781]

To answer another question about the plating, we use a NiB plating to increase surface wear and corrosion resistance. The extensions are not stainless steel, they are 8620 and will corrode if not oiled or otherwise treated. The cost of plating vs Nitride is very close and the NiB has served us well for two years so we will continue to use this process. The extensions are machined for us under contract and then plated at a professional plating company with Aerospace and Defence contracts. We have certificates of conformity for our plating along with all of our other post-production processes.

Thanks for taking the time to provide an explanation.

Further to that would I be correct that Nitride treatment of an assembled stainless barrel would NOT be ideal due to the way the heat from the process would effect the different materials that the barrel and extension are made from?

Reason I ask is because I was looking into having one of the stainless barrels I got from you nitrided.

What would you suggest? Bad idea to do it or not? Thanks

[Maple Ridge Armourer]

Thanks for taking the time to provide an explanation.

Further to that would I be correct that Nitride treatment of an assembled stainless barrel would NOT be ideal due to the way the heat from the process would effect the different materials that the barrel and extension are made from?

Reason I ask is because I was looking into having one of the stainless barrels I got from you nitrided.

What would you suggest? Bad idea to do it or not? Thanks

Yes the extension and the barrel will react differently to the Nitride. We do not recommend doing this.

Furthermore, stainless steel requires some very expensive processes before Nitride to prepare the steel for Nitride otherwise you will experience embrittlement with the case and it would ruin the barrel. This process is very expensive.

[jiffx2781]

Yes the extension and the barrel will react differently to the Nitride. We do not recommend doing this.

Furthermore, stainless steel requires some very expensive processes before Nitride to prepare the steel for Nitride otherwise you will experience embrittlement with the case and it would ruin the barrel. This process is very expensive.

Ok, bad idea. I kinda figured it would be.

Thanks again.

[b_w.]

Curious as to what receiver this was installed in. Did you lubricate the barrel nut? I had to locktite barrels into the upper on the three BCL's I built to prevent the pins from twisting slightly into the soft aluminum while using the reaction rod.