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DPMS 308 Dimension Check


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Hi All, I was wondering if anyone would be able to point me in the right direction. I'm looking for a blueprint for a Gen 1 DPMS 308 lower... or maybe just some confirmation. I have a print for a Noreen Firearms BN308, and a jig from an unknown manufacturer. See attached...

Measuring the jig plates on hand to the print, most of the specs seem to line up. But the deep pocket that is milled for the trigger shows a measurement of 0.75" x 0.39", while the jig measures 0.64" x 0.39". Can anyone confirm which is correct? I can tell the print is a DPMS style, but was unclear what generation is referenced or if there are any dimensional differences between Gen1 / 2 / 3.

Any help would be greatly appreciated!! 

308 print.JPG

Edited by kdog_x
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Ok, thanks for the info. Sounds like 0.64 would definitely be tight, better to need enlarging than trying to material back on 🙂 I haven't found the SSI print, but I'll keep looking. There's a Quentin Defense print that shows 0.70 on that dimension, so slightly closer to your measurment. It's amazing the number of slight differences, I wonder if the differences are critical or if everything would be functional. Doesn't really seem like an area where one would like a lot of slop in the parts. The lower is a "Always Armed" model, not much to go on there other than it's confirmed as a Gen1.

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13 hours ago, kdog_x said:

It's amazing the number of slight differences, I wonder if the differences are critical or if everything would be functional.

I finally had confidence in the ssi one because it checked exactly with a pin layout give by a Trigger company.. maybe it was jp Trigger of some sort, if you do some research you might find that like I did. The trigger and hammer pins need to be nuts on.  Safety needs to be drill in the center of the safety detent hole that comes up from the grip area.  Glad you are trying to make sure things are precise.

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Hmm... when I visit that site and select triggers, there's no troubleshoot link.

I did find this photo though, what I have looks identical to the Colfax tactical. Same pointed trigger guard on the bottom, same casting shape around the selector hole and along the top of the receiver. The shape is pretty unique, so I'd say that's 99% to be the right one. Definitely progress, but unfortunately, I haven't been able to find the complete Colfax drawing with the view from the top 😞


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