Mark IV rubber bumper

1
Recently I noticed that the barrel on my Mark IV was wiggling a bit. I didn't know what was causing it, though, and it wasn't urgent, so I kind of let it slide. Then the last time I went to clean it I noticed that a small rubber piece in the front of the frame was almost completelyy disintegrated. I dug out the remains and then looked in my manual at the exploded parts diagram. Alas, this part is not shown.

A quick internet search later I found out that this part is a bumper that holds the barrel steady. I called up Ruger support and they said they'd send me a new one for free. Yay free!

For those who might someday have this issue the parts are

A404451 Bumper - MKIV
A404452 Steel ball, low carbon 3/32" (Vendor #96455K72) for MKIV bumper

The bumper is mushroom shaped with a central hole running down through it. You put the tiny ball bearing inside it to give you something to push against with a punch when seating the bumper in it's hole.

I later noticed that Volquartsen makes a replacement part for this too. The Volquartsen bumper comes in two packs and is thicker than the Ruger bumper, and it might provide even more stability. I haven't tried it, but if you need to replace the bumper this is an option.

https://volquartsen.com/inventory_configurations/1469

Of course, I now also know that cleaning fluid eats away at the rubber, so I'll probably start having to replace this part once a year or so, depending on how often I fire and clean the gun.
106+ recreational uses of firearms
1 defensive use
0 people injured
0 people killed

Re: Mark IV rubber bumper

3
Too much anal retentiveness ruin rubber parts. Shoot it till it jams then wipe it down with a Kleenex and some oil.
"It is better to be violent, if there is violence in our hearts, than to put on the cloak of non-violence to cover impotence. There is hope for a violent man to become non-violent. There is no such hope for the impotent." -Gandhi

Re: Mark IV rubber bumper

5
Bisbee wrote: Sun Mar 10, 2019 11:34 pm Too much anal retentiveness ruin rubber parts. Shoot it till it jams then wipe it down with a Kleenex and some oil.
+1, although I'd say use a nice twill patch or two, not a Kleenex, to minimize fibrous crap snagged on various edges, and a little Ballistol or BreakFree CLP.

One of the things I love about the Ruger Mark series of guns is their ability to shoot well when dirty. Early this month I shot a couple of the best 30-shot groups of my life (admittedly, a pretty low bar) with my 5.5" MkII, which currently looks like a sewer around the feed ramp, as it so often does. I had a few failures-to-feed on the first or second round when I loaded the magazines fully, but I think that was because the mags were very dry. No problems when I loaded only five rounds.

More shooting, WAY more dry-firing, less cleaning! This is the three-fold path to Ruger Nirvana.
IMR4227: Zero to 900 in 0.001 seconds

I'm only killing paper and my self-esteem.

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Re: Mark IV rubber bumper

6
Bisbee wrote:Too much anal retentiveness ruin rubber parts. Shoot it till it jams then wipe it down with a Kleenex and some oil.
From the mists of time I feel the gentle hand of a Master Gunnery Sergeant. A booming voice saying “the weapon shall be clean”


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