Building out a Ruger MKII from parts / Will a MKIV bolt work?

[whatnickname]

I’ve accumulated just about all the parts I need to assemble a Ruger MKII 22 Pistol in stainless steel with the exception of the bolt. Seems like just yesterday you could find all the MKII parts you ever wanted. Not so today. Went on line at E-bay and purchased a MKIV bolt that was advertised to run in the MKI, MKII & MKIII that the seller advised would require “some fitting”.

Upon examination of the MKIV bolt there are a few minor differences between this bolt and the bolt out of the MKII. Underneath side of the bolt that picks up a round out of the magazine is flat on the MKIV. The MKII bolt out of one of my other pistols has a small raised area right up at the face of the bolt that picks up rounds out of the magazine. The long milled section on the side of the bolt is rounded at either end on the MKIV bolt where the forward edge on the MKII bolt is angled on the end closest to the bolt face. Most notably, the forward edge of the bolt that engages the bolt hold-open piece in the receiver is angled at about 45 degrees on the MKIV bolt whereas this part on the MKII bolt is ground down flat at 90 degrees. Dropped the MKIV bolt in my other MKII pistol and performed a function check. Seems to function just fine.

What modifications do I need to make on the MKIV bolt to make it run in my MKII pistol?

 

[Clemson]

Mark II bolts run $50-75 on ebay. Save yourself some grief and buy the correct bolt.

 

[BBBBill]

From all reports, they are backwards compatible. In fact, the Volquartsen competition bolt is marketed as fitting Mk2, 3, and 4 guns. I use lots of Volquartsen parts and trust them.

I would prefer a Mk2 bolt in a MK2, but I provide the following with no additional comments as I have not attempted to do what you propose... yet. I do have a MK2 and a MK4 bolt. I may try it later and report back.

That said, this from a sale link on Ebay by a seller named arachnosteel -
"This is a Ruger Mark IV complete pistol bolt assembly. It was removed from a new Ruger MK 4 pistol. It includes the firing pin, extractor, and recoil-spring assembly (all the parts as if it were removed from the pistol during field-stripping). The photos are of one of the bolts we are selling; the bolt you will receive will be similar to the one shown in the photos. The bolt is complete, ready for use in a Ruger MK 1, 2, 3 or 4 -- but PLEASE READ the IMPORTANT details below if you are planning to use this bolt in a Ruger MK 1, 2, or 3.

Mark IV bolts can be used in Ruger's Mark I, Mark II and Mark III pistols, including the 22/45 versions, but fitting/gunsmithing work may be required, and certain functions -- like the bolt-hold open, or safeties -- may not work if combined with receivers and parts other than those made for Ruger Mark 4 pistols. Please read the following carefully:

If a Ruger MK 4 bolt is used in a stock Ruger MK 1, the safety, when engaged, will not lock the bolt in the closed or hold-open position. The safety can be engaged (blocking the trigger) while the bolt is cycled to chamber a round.

If a Ruger MK 4 bolt is used in a stock Ruger MK 2, the pistol will function the same as it did with its Ruger MK 2 bolt.

If a Ruger MK 4 bolt is used in a stock Ruger MK 3, the bolt will not fit, and the pistol will not function unless the loaded-chamber indicator is removed from the pistol first; once the loaded-chamber indicator is removed, the pistol will function the same as it did with its MK 3 bolt.

This Ruger MK 4 bolt would be a direct replacement ("drop in" part) in a stock Ruger MK 4 pistol.

This Mark IV bolt would be a "drop in" fit for a Tactical Solutions PAC-LITE IV™ upgrade barrel/receiver since the PAC-LITE IV is designed to use Ruger® Mark IV™ or Mark IV™ 22/45™ parts. This Mark IV bolt may not be a drop-in part for earlier versions of a Tactical Solutions PAC-LITE barreled-receiver; you would need to consult with a gunsmith if you were planning to use this Mark IV bolt in an earlier version than a PAC-LITE IV.

Firearm bolts should be installed by a qualified gunsmith or persons with similar technical/mechanical skills. Please check with your gunsmith about any intended uses you may have for this pistol part."

 

[whatnickname]

From all reports, they are backwards compatible. In fact, the Volquartsen competition bolt is marketed as fitting Mk2, 3, and 4 guns. I use lots of Volquartsen parts and trust them.

I would prefer a Mk2 bolt in a MK2, but I provide the following with no additional comments as I have not attempted to do what you propose... yet. I do have a MK2 and a MK4 bolt. I may try it later and report back.

That said, this from a sale link on Ebay by a seller named arachnosteel -
"This is a Ruger Mark IV complete pistol bolt assembly. It was removed from a new Ruger MK 4 pistol. It includes the firing pin, extractor, and recoil-spring assembly (all the parts as if it were removed from the pistol during field-stripping). The photos are of one of the bolts we are selling; the bolt you will receive will be similar to the one shown in the photos. The bolt is complete, ready for use in a Ruger MK 1, 2, 3 or 4 -- but PLEASE READ the IMPORTANT details below if you are planning to use this bolt in a Ruger MK 1, 2, or 3.

Mark IV bolts can be used in Ruger's Mark I, Mark II and Mark III pistols, including the 22/45 versions, but fitting/gunsmithing work may be required, and certain functions -- like the bolt-hold open, or safeties -- may not work if combined with receivers and parts other than those made for Ruger Mark 4 pistols. Please read the following carefully:

If a Ruger MK 4 bolt is used in a stock Ruger MK 1, the safety, when engaged, will not lock the bolt in the closed or hold-open position. The safety can be engaged (blocking the trigger) while the bolt is cycled to chamber a round.

If a Ruger MK 4 bolt is used in a stock Ruger MK 2, the pistol will function the same as it did with its Ruger MK 2 bolt.

If a Ruger MK 4 bolt is used in a stock Ruger MK 3, the bolt will not fit, and the pistol will not function unless the loaded-chamber indicator is removed from the pistol first; once the loaded-chamber indicator is removed, the pistol will function the same as it did with its MK 3 bolt.

This Ruger MK 4 bolt would be a direct replacement ("drop in" part) in a stock Ruger MK 4 pistol.

This Mark IV bolt would be a "drop in" fit for a Tactical Solutions PAC-LITE IV™ upgrade barrel/receiver since the PAC-LITE IV is designed to use Ruger® Mark IV™ or Mark IV™ 22/45™ parts. This Mark IV bolt may not be a drop-in part for earlier versions of a Tactical Solutions PAC-LITE barreled-receiver; you would need to consult with a gunsmith if you were planning to use this Mark IV bolt in an earlier version than a PAC-LITE IV.

Firearm bolts should be installed by a qualified gunsmith or persons with similar technical/mechanical skills. Please check with your gunsmith about any intended uses you may have for this pistol part."

That is extremely helpful. Can’t thank you enough for going to this trouble for me. I will range test my project gun as soon as I can get the standard tapered barrel replaced with the bull barrel I just purchased. From a function check prospective, the bolt locks back as it should and rounds feed properly from the magazine.

One person on the Ruger Forum opined that the bolt lock in the MKII may batter and wear excessively due to the way the MKIV bolt is configured at an angle. Based on the schematic drawings I’ve seen of the MKIV the bolt locking piece would not appear to be configured at the engagement point much more differently than the same part in the MKII. I’m gonna keep an eye on the wear of the bolt and locking assembly. Should not be a problem but when you’re building a parts gun you never know how it’s going to turn out. Think I’ll give Clark Custom Guns and Volquartsen a call and see what they suggest. I expect I’ll learn quite a bit from this project. I’ll be glad to share my results.