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View Full Version : So..how do U stop hammer pin from rotating?


Ronin6.8
August 11, 2017, 18:38
I was cleaning my lower and noticed that the hammer pin was rotating when under load with the hammer spring, with out the spring installed, it's as smooth as butter?
Was wondering if anyone had a fix for this?
I've seen photos of lowers that someone tried to staking around the pin:facepalm: not going to happen! Over time I could see where this would elongate the pin hole.
Any advice would be greatly appreciated

DakTo
August 11, 2017, 19:02
For best results replace it with a better pin.

ActionYobbo
August 11, 2017, 19:34
Its the hammer causing this problem. Sometimes lubrication will resolve this issue if the hole is smooth and with out beaver marks

Ronin6.8
August 11, 2017, 20:27
I'm using a new U.S. Made hammer, and break free for lube, I took the hammer and pin out of the lower and can spin the hammer like a top, pin is smooth and round.
Surly someone out there has an idea for a fix?

4markk
August 11, 2017, 20:50
Is it a metric pin in an inch lower?

Ronin6.8
August 11, 2017, 21:00
No sir, UE59 L1A1, my UB58 L1A1 dose the same thing?

Illurian00
August 11, 2017, 22:25
I'm using a new U.S. Made hammer, and break free for lube, I took the hammer and pin out of the lower and can spin the hammer like a top, pin is smooth and round.
Surly someone out there has an idea for a fix?



Quite a few surly someones' around here.

OLDMANPBK
August 11, 2017, 22:26
I don't know how much this will help you as you may not have the measuring tools, but I'll give you the specs. These will be the maximum allowable sizes. The hole through the hammer .204. The hole on the right side of the receiver .299. the hole on the left side of the receiver .206. The shank of the hammer pin no less than .201. And the hammer pin shoulder no less than .293. Going through some of my inch lowers I found one that was on the low limit of all the specs and undersize on the hammer pin shoulder- .290 vs .293. This may be allowing the pin to move with the hammer. The hole through the hammer was also a tiny bit rough, which I'm sure doesn't help.

SAFN49
August 11, 2017, 23:16
Was wondering if anyone had a fix for this?
I've seen photos of lowers that someone tried to staking around the pin:facepalm: not going to happen!

Center punch. This is how it was done by the military's that used the L1A1's. If it's good enough for them it should be good enough for you. I had a NZ contract lower that was punched.

tac-40
August 12, 2017, 07:56
Had the same problem with an US Made hammer, pin and sleeve. The sleeve began binding on the pin and eventually caused issues in reliability (firing). After figuring out the problem, tried to polish all the surfaces smooth but finally replaced the hammer, pin and sleeve with OEM parts. No issues now and have over 10K rounds through it.

4markk
August 12, 2017, 09:46
I'm using a new U.S. Made hammer, and break free for lube, I took the hammer and pin out of the lower and can spin the hammer like a top, pin is smooth and round.
Surly someone out there has an idea for a fix?

If the pin is that tight in the hammer, then it sounds like you have a metric hammer on an inch pin.

Inch pins are thicker than metric. An inch pin should not go into a metric hammer UNLESS a lot of force was added. I had an SA lower awhile back that someone forced inch pins into the hammer and lower. Then wondered why it wasn't working. If you have to apply force, something isn't correct.

J. Armstrong
August 12, 2017, 11:24
Ditch the US hammer, replace with a milsurp one. Any other US fire control parts, scrap them, too. Few if any US FC parts are worth a damn anyway.

Ronin6.8
August 12, 2017, 13:16
Thanks to all, I was trying to make it 922r compliant, do to NFA item in my locker, I do know 3guys personally that have had welfare checks in the past, hopefully, we'll have at least 3 1/2 year before that chit fires up again.

Thank you OLDMANPKK. I have calipers, but no pin gauges, I do have a pill of drill bits that might get my there.

Thanks SAFN49, if it comes to that, I'll try it from the inside, slowly but surely.

Thank you tac-40, I did notice that the trigger pull was much stiffer with U.S. Parts.

4markk, if the metric is bigger, is it possible to machine a metric pin down to a inch?

Thanks J Armstrong if it get to that, I'll have to do it :sad:

4markk
August 12, 2017, 13:31
4markk, if the metric is bigger, is it possible to machine a metric pin down to a inch?

Thanks J Armstrong if it get to that, I'll have to do it :sad:

When I said that the inch pin is thicker, I don't understand how you got that to mean that the metric pin is bigger.

The inch pin measures about 0.201" diameter on the shaft.
The metric pin measures about 0.195" diameter on the shaft.

So the hole on the hammer should be about 0.204" diameter (as stated before). If it is less than it is probably a metric hammer.

There are many good US made Hammers, triggers, and sears. I have several in my FALs with zero problems.

Measure what you have and post. We should have a better idea as to problem then.

Ronin6.8
August 12, 2017, 13:54
My bad lol, :whistling:

Ronin6.8
August 12, 2017, 14:35
Ok U.S. Hammer .202, pin .201 in the middle and .199 at the left end that goes through the lower housing hole.
Found old hammer, .2045, left hand lower housing is .206:sad:

Ronin6.8
August 12, 2017, 14:39
Right side of lower .300

Ronin6.8
August 12, 2017, 16:24
Ok.. Reinstalled OEM hammer and it's fine now, I left the the trigger and sear in, actual has less creep.
So my ugly parts replaced count is still at 7:]
Thanks again to all

djfin
August 12, 2017, 16:49
And just how many people are going to count the US parts in your rifle?? Just because you have an NFA does not mean that you are required to let anyone look at anything else. And second how many agents would know the difference between US and import parts.

4markk
August 12, 2017, 19:50
Ok.. Reinstalled OEM hammer and it's fine now, I left the the trigger and sear in, actual has less creep.
So my ugly parts replaced count is still at 7:]
Thanks again to all

Or you could've chased the hole with a #6 cobalt drill.

And just how many people are going to count the US parts in your rifle?? Just because you have an NFA does not mean that you are required to let anyone look at anything else. And second how many agents would know the difference between US and import parts.

Nothing wrong with obeying the law and publicly stating so.

Ronin6.8
August 12, 2017, 20:41
Thanks 4markk
I'll check to see if we have a reamer at work Monday