MODULUS ARMS JIG REVIEW

[Prepped and ready]

I have used the same jig on several lowers. With just a little of the color being rubbed off, mine are still in good shape. I have both the 15 and 10 jigs.

Out of 4 different jigs Ive used, these are by far the best.

[robodeer]

Thanks Prepped, that's exactly what I wanted to hear.

[spyde12]

I've done a couple using their ar15 jig. The first lower was with a frontier billet and the trigger pocket looked like yours. However, the second one turned out perfect and oddly enough, it was with a harder aluminum Tactical Machining. So I blame the cause of the poorly milled trigger pocket with the operator (me). I do agree that the trigger pocket is off by a little bit and that's been mentioned in other threads. However, this didn't cause any functional issues. The issue that I did encounter with both lowers was with the drill hole closest to the magwell. I got a little more that I should've. I don't think it's my drill press because all the other holes were aligned. Like I said earlier, it's still functional. I would recommend modulus arms to others. I'm also interested in giving the easy jig a try as well.

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[spyde12]

For those that have done multiple lowers, what kind of wear have you seen? From the sound of it, it seems like the side panels are the fastest to get a bit larger, while the top guide loses some material as well from the endmill. I'm trying to figure out how delicate I'd have to be.

I've done 2 so far. The drill plate has some wear on it because I caused the stopper to rub while drilling. However, the holes are still circles and not oblong. In my limited experience, the key is to start the drill bit when it's in the hole and having a drill press made this easier to control. There is some wear on the safety selector, but that was my fault. The thing that's cool about the modulus arms side plate is that you can flip it around and put it on the other side. Now the safety selector that got a little worn is no longer being used and you got yourself a new and clean selector hole. As I said earlier, get a drill press. It took little effort to complete the holes and I didn't even try to rush.

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[Victor Cachat]

I just finished my second LR308 on mine and noticed two things:

The side plates somehow ended up misaligned during one of my reconfigurations, so the right side was a little lower than the left.
As far as I know, this only resulted in the pocket being open more on one side.
The pins and selector seem to fit fine, so it must have been right when I drilled the side holes.
It is a good idea to drop the depth probe of your caliper through the holes that hold the drill guide to make sure the top of your receiver is square with the top plate.

The second thing was that the magazine well end can flex visibly if you exert moderate pressure with the mill or drill.
Again, it still seems to fit when done.

All in all, the two changes I would like to see are less space between the top and the top of the receiver and more beef on the top plate (which means less on the drill guide.)

[Joe Blowitup]

Are you guys using a drill press? When I did mine I noticed when the table wasn't tightened down it wasn't square to the bit causing them to be off center. Just a thought.

[spyde12]

Are you guys using a drill press? When I did mine I noticed when the table wasn't tightened down it wasn't square to the bit causing them to be off center. Just a thought.

I used a WEN drill press with TAP cutting fluid. Looking back, I think you have a valid point. I did tighten the table the second time around. I guess the wobble, however minor is enough to throw it off a bit.

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