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P938 Two-piece Guide Rod - Permanent Fix?

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https://sigforum.com/eve/forums/a/tpc/f/150601935/m/3520067534

January 06, 2018, 05:00 PM
burnetma
P938 Two-piece Guide Rod - Permanent Fix?
OK, I am at my wits end with my P938. I have ~ 1700 rounds through it now and the guide rod keeps loosening despite thorough cleaning and application of Loctite Red. I went to the range today and got 35 rounds off before the guide rod was protuding.

Any other solutions?
January 06, 2018, 09:07 PM
vthoky
I'll show my ignorance and ask, why is the guide rod a two-piece thing? Could it be a single piece?

I ask, not to be a smart-aleck, but because I don't understand.

-----

Edit: having taken a look at it, I see it's likely an economics thing. That could be machined from a solid, but would be more economical as a two-piece.




God bless America.
January 07, 2018, 07:06 AM
burnetma
Yes, it is a 2 piece due to the economics and manufacturability of making that design as a single piece. I have given some limited thought to a redesign, but have not put it into motion, yet.
January 07, 2018, 11:49 AM
vthoky
I wonder if the "rod" could be serrated and press-fit into the "block," rather than them being threaded together.




God bless America.
January 21, 2018, 05:41 PM
burnetma
quote:
Originally posted by vthoky:
I wonder if the "rod" could be serrated and press-fit into the "block," rather than them being threaded together.


Your idea has merit.
January 21, 2018, 05:47 PM
vthoky
I'm tempted to pull mine apart and start measuring.

We do a lot with serrations at work... it's not that tough to do (given a proper die), and you really have to force things apart if pressed together correctly.

Now I'm wondering if I can get some time with the CMM this week.

ETA: Heck, a new one is just $22. Maybe I should just go ahead and get a spare, and start measuring from it. I'd have a "sample of two" on hand for measurements....




God bless America.
January 22, 2018, 02:24 AM
bumper
I just cleaned and degreased mine and applied red Loctite again - it started coming apart. I was more fastidious cleaning this time.

If the threads come apart, I wouldn't hold a lot of hope for a spline press fit either. Before that, I'd cross drill and put pin through the threaded area for a SS roll pin.

Heard there is a one piece aftermarket guide rod to be out shortly for around $40 something. No other info though.
January 22, 2018, 08:16 AM
henryaz
 
The P220-10mm also has a two piece guide rod, but the spring is captive on the rod. I noticed mine backing out several months ago, and I did the thorough cleaning, inside and out, with acetone, used red loctite to reassemble, and so far it has held. Perhaps the captive spring helps keep it from unscrewing itself.
 
March 17, 2018, 06:20 AM
burnetma
I disassembled and soaked both pieces again in acetone then thoroughly vcleaned out the threads again. This time I used JB Weld instead of Loktite during assembly. I let it set for 24 hours and then reassembled. Thus far I have put 250 rounds of mixed ammo down range, including 14 rounds of +P 124 gr HST's and no movement.

I got a spare guide rod from Sig just in case anything funky happens, but thus far it looks promising.
November 30, 2021, 10:28 PM
burnetma
BTW, my JB Weld guide Rod fix is still working flawlessly. I do not know the round count since the fix, but it is likely 600×
January 17, 2022, 10:29 AM
coloradohunter44
Are all P938 subject to this, or only ones manufactured at certain times? Does Sig offer a different rod?



"Someday I hope to be half the man my bird-dog thinks I am."

FBLM LGB!
January 17, 2022, 11:01 AM
vthoky
quote:
Originally posted by bumper:
I just cleaned and degreased mine and applied red Loctite again


I'm not doubting you a bit, but I'd like to ask: what's the number on the red Loctite you used? We use it at work in a stainless steel application, and we have to torch it to get it to come loose.

quote:
Originally posted by coloradohunter44:
Does Sig offer a different rod?


I'm not sure Sig offers one, but several others do. A quickie search brings me these two:
- Midwest Gun Works
- SSGuiderods.com




God bless America.
January 18, 2022, 09:15 PM
coloradohunter44
Vthoky, thanks for the info. Looks like I should order one of those, even though my P938 has yet to act up.



"Someday I hope to be half the man my bird-dog thinks I am."

FBLM LGB!
January 19, 2022, 05:31 PM
vthoky
I'm very glad I could help.
I probably should get hold of one as well, though -- like you -- I've not had an issue with the P938s I've shot.




God bless America.