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Here is what I have found regarding the Ruger MK III (and MK II) feed ramp jamming problems reported by many people.
The MK II magazine shown below is over 20 years old and will feed virtually any type of ammo.
I now find that the spare mags that ruger sells for both MK II and MK III have the same deep cut at the mouth.

I am posting a link to this page to the forums at:


I finally purchased a Ruger MK III Hunter after having fired several MK II pistols over the years.
I had always found these to be excellent pistols and not at all picky about the type of ammunition used.

I went to the range and had a feed ramp jam on round #1 of clip #1 when using the same type of ammunition that fired flawlessly for several hundred rounds through a MK II the week before.
I have since fired ~ 300 rounds of another brand of ammunition through the gun with no trouble whatsoever.

After searching the net for others with feed ramp jam issues, I find that many have had this problem - the most common solution is to only use round nose bullets, specific brands, etc.

Unfortunately, bulk packs of the "right brand" of ammunition are still in short supply in my area.

The many comments and solutions posted in forums regarding the stovepipe / extraction pin / magazine seat height and lip tweaks are correct for those specific ejection problems.

As yet, I find that nobody has identified the difference between the MK II and MK III magazines when the seat height and clearances are correct (mine are)...
The mouth of the MK III magazines is cut ~1/16" - maybe 3/32" lower than the MK II magazines.  That small extra bit of metal helps to lift the bullet tip (any type of bullet) just enough that it starts properly on the feed ramp. In any case, when the tips are up like this, the magazine feeds flawlessly as Bill Ruger had intended.
This shows where the bullet tips are down due to the rim of the top bullet "camming" over on the shell of the bullet below. 
Note that as the bullet arrives at the top of the magazine, the rear lips of the magazine cause the bullet to move ~1/16" forward.  Again, the extra metal on the MK II magazine lifts the tip of the bullet (virtually any type of bullet) so it starts properly on the feed ramp.   I have repeated this with several types of ammo.

This only happens with more than one bullet in the magazine and is common for any type of rimmed cartridge.   Note that all but the first bullet in the magazine are "cammed" over and rest on the shell below (all other bullets in both MK II and MK III magazines except the bottom one. - simply making sure the top bullet is pointing up before inserting the mag doesn't do anything for the bullet below).
As the bullet arrives at the top of the magazine, the tip of the bullet in the MK II magazine ends up resting on the lower lip of the magazine.  For the MK III, the top bullet is resting on the cartridge below   Sometimes the tip of the bullet will pop up and feed normally, but for the MK III magazine, this is often not the case.
This shows the relationship for a bullet that has been reinserted in the clip after a feed jam.  Again, it is "cammed over" in the same tip-down down position shown in the previous photo.  Again, for the MK III, the bullet is resting on the cartridge below.
When the bolt closed the cartridge simply moved forward straight out the wider mouth and hung on the feed ramp.  This does not happen with the MK II magazines. 

Again, the extra material on the lower lip of the MK II magazine lifts the tip of the bullet that little extra bit to prevent jamming on the feed ramp (assuming the magazine seat height is correct in the frame). 

This may actually be a case where the extra burr material sometimes mentioned on the magazine release buttons helps the feed ramp jamming problems by holding the clip a little higher.  Then the simple tweak of the magazine feed lips makes it all work.  Furthermore, in the case where people have an occasional FTE, these guns probably don't have feed issues.  The rim of spent shell catches the rim of the top bullet in the magazine on the way by causing the tip to pop up and feed correctly.  It seems each of these problems are related.

As yet, I don't have a simple fix for the problem I am seeing... other than one suggested method where a penny thickness shim can be JB-Welded to the bottom of the feed ramp and shaped to match the ramp profile. 

In any case, this is a new gun supposedly at the top-of-the-line in a series with historic reliability.
I had a MK II that proved these pistols can reliably digest almost any type of ammo.
I should not have to be concerned with worrying about finding 22LR catridges that work, much less trying to come up with modifications to make it work on my own.

I am trying to get a response from Ruger and will continue to post as I have new information...

It seems that the somebody at Ruger made a poor decision when doing the design layout of the new metal stamping dies for the MK III (and newer MK II) magazines. 

There are a huge number of these out there. 
Maybe they have just chosen to ignore the problem rather than fixing the problem and issuing a recall on these magazines.

Please forward any comments to the forums listed above.

Note that the MK II magazine is about 20 years old.  Since I wrote this, I looked at a new MK II mag at the gun store the other day and find that it is cut the same way as the MK III mag shown above.  This indicates that they are probably now using the same stamping die for the body of the magazine, then a second stamp for the magazine safety and side-style magazine release tabs.  This may explain why people have also been having issues with the MK II pistols for the last few years.