Lower egging prevention

[Offmarksman]

There has been several threads on this, and my Delrin pin has been mentioned before. Kickstand and myself have used these for a few years and have shot thousands of rounds with them. While I don’t plan to make them for sale, I would encourage others to make them. I simply turned down 1/2 Delrin rods to the same dimension as the oem pins (I actually made them a little larger and fitted them to my upper and lower). I maintained thr oem steel spring clip with the Delrin pin.

Equally and possibly more important, I shim my uppers to fit my lowers. There are many methods to do this, but I have found that using furnace tape (multiple layers) until I have a tight fit, has worked very well. I wrap the tape around the top edge of the back of the receiver where the upper slides in (see pic).

 

[Offmarksman]

 

[KickStand]

The one you sent me is a perfect fit in my M11 and M11/9, I really appreciate you giving me one.
I think you actually sent me one that went to the moon thanks to the USPS.

I also hope someone will bring these to market and there’s likely better material out there than Delrin but it’s works great.

 

[Deerhurst]

Crap! Totally got sidetracked on making some for somebody!

Delrin is easy to work with and decently wear resistant. Pins need something hard but softer than the steel.

 

[Galil#1]

Reinforcement tabs for the MAC family, i.e. 10/9mm.
The UZI SMG full size grips have that inside extra metal reinforcement tab around the takedown pin. Rather have these vs. some plastic for such a key pin/structural area etc. IMHO. - Not against plastics an such, Glocks rock right?

 

[Hey...]

Nobody mentions the sear/selector pin but it takes a beating too each time the bolt lands on the sear.

Do this test, with the gun unloaded pull and release the trigger with the bolt closed; notice the sear pin or selector on the other side move as you pull and release the trigger repeatedly?

 

[Galil#1]

^^^^^^^ Yes Exactly always some movement on MAC and UZI I noticed and do push back on. OCD?

 

[SecondAmend]

Anybody know what Battlefield Vegas does? I've read that on their M16s, they have "anti-rotation" pin braces on the hammer, trigger, and sear pins to prevent the receiver from degrading due to damage and wear.

 

[brenbuilds]

I don't have a lathe, but if any of you fine gentlemen happen to produce several Delrin take down pins, I will happily purchase several. I have a very early JAWS Avenger that lack tabs ( all original Hatton/JAWS lowers did not have tabs). Delrin is the engineer's plastic!

 

[Deerhurst]

I'm an engineer. I kinda hate delrin. It's has its uses and is pretty slick. I really like hylarZ but it is a nylon and therefore fairly soft. Extremely wear resistant. I dislike the smell of delrin when machining on it. Smells like glycol.

I'm doing a bunch around my house right now but if I have a chance and some delrin in the chowder box I'll turn a few. Just got some tooling in I want to play with too!

 

[KickStand]

Bumping this thread.
I hope that someone out there has decided to make these.

 

[skoda]

I made one out of brass and shot with it a bunch. I didn't see any appreciable deformation of the brass. If there was enough force there to deform the steel receiver I would have seen deformation of the brass.

 

[Deerhurst]

The brass will deform before steel.

What type of pin do people want?

 

[Galil#1]

? If it ain't broke why F it up?

 

[Offmarksman]

The Delrin works, but the Brass makes a lot of sense. I’d buy a few brass ones from you, If they aren’t too expensive. I could make them myself, but not sure if or when I’ll ever have the time to do it😂

 

[skoda]

Brass is very easy to machine and it's stiffer than any polymer or aluminum but still much softer than the steel receiver. If you have to have a pin made of something besides steel I'd go with brass. But like I said above, I don't think that there's any real threat to the receiver. Maybe if you are taking the pin in and out a bunch of times to swap uppers you might eventually get some wear but that's all that I can think of as a reason/need/use for a non-steel pin. I suppose that one could make a few bucks selling some just to alleviate unwarranted fears but that's about it.

 

[Galil#1]

^^^^ Yep seems like a solution looking for a problem. Practical Solutions/Sam welded metal reinforcement tabs in my MACs receiver, that's all. Highly recommend.

 

[Offmarksman]

If I can spend a few bucks in a consumable pin, in lieu of having to send my lower to Sam, I’ll spend a couple of bucks. I too have the reinforcement tabs, but changing uppers frequently, and shooting rifle caliber with my lower are a concern for eventual egging. If you don’t think a pin is necessary, cool. I for one, would like the option.

 

[skoda]

There you go Deerhurst, your first customer!

Here's my crappy homemade pin. It's ever so slightly too big in the diameter of the shaft so I was 'hammering' it with whatever was handy at the range to go in which caused the scratch lines. Usually a screwdriver handle or the heel of my hand. One made with better tooling and slightly smaller would look better after use.

But there are no indentations from the upper hammering on it against the lower which is the main point of my little experiment.

 

[A&S Conversions]

At least from my perspective, I would think that the bigger issue would be the QC of the original hole in the front of the receiver and the QC of the hole in the uppers that are used with that lower receiver. It is my understanding that originally these guns were designed as cheap, almost throw away instead of repair. Of course today they are five figure items. If the two holes match up and don’t have room for the upper to move back and forth, I can’t imagine that removing the pin to swap uppers would cause any wear at all.

To me it would be an over sized hole that would cause wear to the front pin hole. If there is additional room for the upper to move, that movement would be what would hammer on the pin to cause wear. I would think that the bigger concern for front pin wear would be the interface of the upper pin hole to the lower pin hole and of course the pin itself. The upper has so much more surface area on the pin, compared to the two sides of the front pin holes of the sheet metal receiver. If there is a movement, it will be the thin sheet metal receiver holes that will tend to wear.

So if there is no appreciable wear on the front pin holes of your lower receiver, it would seem to me that it would be any slop in the hole of the upper receiver allowing movement would tend to be the cause of the front pin holes of the lower to become oblong. Just a thought.

Scott