Gunsmithing JPE JP-15MR forward pivot pin won't push through

[ANGLICO]

Hello,

I just received my brand new JP-15MR.

While trying to attach the upper and lower, the forward pivot pin will not push through the eyehole of the upper assembly.

The rear pivot pin pushes through perfectly.
The front pivot pin pushes through easily if the upper assembly isn't attached.

I've only used M-16s in the Marines, and I didn't have this issue with them.

When I align the pin with the hole and shine a light into it, it looks like a snug fit, and it has perfect alignment, but it won't push through.

It seems the hole may be a tiny fraction of a millimeter off center.

So should I try to bore it out a tiny bit, grease it, or just bang it in with a hammer?

 

[spife7980]

You spent a lot of money on it, see what they have to say about it before you go whacking stuff with a hammer.

 

[Darqusoull13]

Give it a little lube. It's probably one of the Microfit pins. Not my favorite thing but I know quite a few people love them.

 

[Terry Cross]

Sounds silly but when putting your upper on, pin the front first and then try to push your rear pin.
Sometimes the hole on the upper rec rear lug has a larger chamfer and is easier to get started.

Like they said above, DON'T try to hammer the pin in to start it. Be patient enough to contact them first.

./

 

[ANGLICO]

Sounds silly but when putting your upper on, pin the front first and then try to push your rear pin.
Sometimes the hole on the upper rec rear lug has a larger chamfer and is easier to get started.

Like they said above, DON'T try to hammer the pin in to start it. Be patient enough to contact them first.

./

I did try that. I also flipped the lower around to try and put the forward pivot pin into the rear hole and vice versa.

When reversed, the forward pivot pin inserts easily through the rear hole.
When reversed, the rear pivot pin inserts easily through the first forward hole but stops at the second forward hole.

So it seems to be an issue with the hole itself. Going to try lube next.

 

[Stackon212]

Try lubing first. I don't see a problem with running a drill bit through to get a little bit more tolerance. I've done that several times on a Poverty Pony (obviously not JP price range).

It's a gun, meant to be dinged up. Who gives a shit. If it bothers you then just rattle can it. Problem solved!

 

[ANGLICO]

Try lubing first. I don't see a problem with running a drill bit through to get a little bit more tolerance. I've done that several times on a Poverty Pony (obviously not JP price range).

It's a gun, meant to be dinged up. Who gives a shit. If it bothers you then just rattle can it. Problem solved!

Tried lube. No joy.

Yeah I bought JP due to their reputation for building high quality rifles, specifically because I didn't want to deal with issues like this, so it's fairly annoying to pay a premium for a rifle then still have to deal with fitment issues.

I'm still operating under the assumption that I'm doing something wrong and will wait to hear back from their customer support.

 

[Stackon212]

@ANGLICO

Sorry, you had a bad experience with an expensive lower. I took a drill bit through the front take down hole on several Anderson lowers (poverty pony). Common problem with Anderson lower.

While you're waiting for customer service to reply, I'd suggest you try this:

1) Completely removed the front take down pin (also detent and spring) from the lower. Keep the rear take down pin attached as is.
2) Attached the upper/lower via the rear take down pin. Try to insert the front take down pin (not attached to the lower). If the front take down pin, by itself, can easily slide through the upper/lower then your upper/lower combo is aligned correctly.

Either your "detent spring" is too long OR your detent spring hole is too shallow. This put too much pressure between the detent and the channel in the pin.

If this is the case, just cut 1 coil of spring off of the spring and reassemble the assembly to see if it works. Keep cutting additional 1 coil off the spring until you can slide the pin through.

Good luck!

 

[striped1]

I cannot believe that they didn't test fit the upper and lower together before they shipped it out to you.

 

[ANGLICO]

The more I've messed with it, it seems as if the forward pivot hole was drilled at a very slight angle. I measured the hole openings and they are the same diameter. It would also explain why the pin partially penetrates the hole when flipped, but not fully. From trying to press the pin in so many times, there is now a slight fingernail shaped patch of bare metal on one side of the hole, meaning the pin does not line up exactly right, which would also explain why in one direction (the correct orientation) I can't get it in at all, and when flipped I can only get it in part way.

 

[ANGLICO]

Dustin from JPE called me and suggested I tap it in with a hammer. He said the tolerances were often tight on these rifles. It wouldn't budge, even with a hammer, trying to push it in the correct direction, so he had me flip the receiver, which allowed it to go in about 50% of the way, then hammer tap it in the remainder of the way.

After that, it required a hammer and screwdriver to back it out, after which I flipped it back the correct direction, and again had to use the hammer but this time it went in with a reasonably (not overly) forceful tap. A 'firm' tap, not a 'light' or 'heavy' tap. And the pin inserted snugly.

Now to go to the range.

Thanks to Dustin, EuroOptic, and the guys here who helped.

 

[1moaoff]

Was this a full JP build purchased from them?

 

[ANGLICO]

Was this a full JP build purchased from them?

Full JP rig, purchased through EuroOptic.