BCG Bolt Carrier Group – Viking Armory

iGauging Firing Pin Protrusion Gage Holder

After I made the plugs for the iGauge to check firing pin protrusion I realized 2 things.

1. I needed to sand down the plug just a bit so it would fit into the hole to get a negative reading.

2. I still had a hard time holding the bolt in a consistent manner. So I came up with the iGauge Firing Pin Protrusion Tool:

Naked:

iGauging Firing Pin protrusion Gage holder In the begining — iGauging Firing Pin protrusion Gage holder, 1st try

Dressed:

Then I added spots for boat tail NO-GO and Field Gage:

Naked:

iGauging Firing Pin protrusion Gage holder with no-go holders — iGauging Firing Pin protrusion Gage holder with AR-15 boat tail No-Go and Field gauge holders

Dressed:

iGauging Firing Pin protrusion Gage holder with Friends — iGauging Firing Pin protrusion Gage holder with AR15 bolt, boat tail no-go and field gauges

Stuck 4 non-slip soft rubber feet on it:

iGauging Firing Pin protrusion Gage holder Back

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All Documents posted on this site are for informational use only. If you make ANY modifications to your Weapons based on this site, you do at your own risk! If done incorrectly, you can render you weapon unsafe and / or unusable.

More HERE: https://viking-armory.com/?page_id=723

McMaster-Carr AR parts list and cross reference

Here is a list of McMaster-Carr parts for the AR platform. Enjoy!

Nugget of knowledge I did not know. You can search the mil-spec part number in Mcmaster-Carr. I had never tried before, worked like a champ!

McMaster-Carr-Web

Download the PDF HERE

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More HERE: https://viking-armory.com/?page_id=723

iGauging Plug for Firing Pin Protrusion Measurements

I was watching this video from School of the American Rifle: 5 Colt BCG Physicals (Video link starts at 16:06) and noticed that he had to modify one of the included extension shafts of the iGaging Digital Depth Indicator Set so the firing pin would not go into the threaded hole. That got me thinking about printing something up. This is what I came up with.

iGauging Firing Pin Plug01 — iGauging Firing Pin Plug 01

The threaded plugs on the bottom don’t have the ejector notch the the top two have. I like the notched one better. I don’t have to remove the ejector to use. Both are sized to fit snug in the bolt face without getting stuck by the extractor. The plugs also help hold the bolt in place while testing.

The bottom is very smooth and will be able to help you get accurate and constant readings. AR-15 firing pin protrusion should be 0.028 to 0.036 Check out the reference page for more info.

It is difficult for me to hold everything in place to get an accurate reading. I think I will start working on a holder. More to follow.

You can download the 3D printer files HERE.