Great discussion, thanks. I've been considering a new Mark IV. (My son "stole" my utterlu reliable Mark III for his wife.)

92FStech— how were the Ruger uppers transferred to you? As an other or pistol?

I believe he listed them as other, but I'm not 100% sure as that was his part of the form, not mine. I'm just using them as pistol uppers, so to me it doesn't make much difference.

Was reading yesterday that both the Tandemkross and the Volquartsen kits use lighter components to reduce lock time, and some have reported light strikes after installing them. Anybody here have similar issues? The factory trigger isn't perfect, but it's not so bad that I'd be willing to trade reduced reliability for a better pull.

I felt the need to update this as this gun has been a bit of a journey.

Some time after my last post I bought a TandemKross BlastPack and stuck it in the gun...this replaced the hammer, sear, and added the "Blast Shield", which deleted the mag disconnect. I don't care for flat triggers, so I didn't want the full trigger kit. The Tandmekross parts improved the pull some, but I started getting short-strokes on the first round out of the mag, and also had an occasional light strike.

I pulled out the TandemKross parts (except for the blast shield), polished up the factory hammer and sear, and put them back in. This eliminated the light-strike problem and most of the short strokes, and while the polishing improved the pull quite a bit over stock, there was still a lot of creep before the break. Looking at the action, I'm pretty sure this was casued by the factory trigger bar flexing as it applied pressure to ovecome the wall...I could actually watch it flex with the upper off.

I decided to bite the bullet and just buy the Volquartsen "Accurizing Kit" like I should have done in the first place. I've got about 500 rounds through it with the kit installed now, with zero light strikes and only one short-stroke that I think was caused by my 8 year-old limp-wristing. The trigger pull is awesome, and the quality of the parts is undeniable. The trigger bar, in particular, is much more rigid than the factory part, and uses a round stud to ride against the return spring plunger which minimizes contact compared to the flat protrusion on the factory bar.

The trigger pull is excellent...comparable to my MkII. The trigger itself is nicely finished and has a comfortable curve to it. My 8 year-old and I gave it a workout this afternoon and apart from his one short-stroke it was flawless. It was only his second or third time shooting a handgun and he was cleaning the 6" plate rack at 12 yards with this thing, it's that easy to shoot.

If you're on the fence about spending the money on the Volquartsen kit, just do it. Yeah, it's kind of expensive, but it really is that good.

Dude, we could have saved you a bunch of time and heartache. Lol. Volquartsen. That is like “I will take gun nuts for $1000, Alex” easy.

Yeah...some of us are just slow and have to learn the hard way .

The Volquartsen kit is what I installed as well. Deleting the mag disconnect is a bonus while giving you a great trigger.

I'm glad you & your son are now enjoying the Mark IV instead of trouble shooting it. My Mark IV lite suppressed always brings smiles to anyone who shoots it.

I think you need a charging handle extension for the Mark 4. The Mark 2 bolt is larger and easier to rack.
Link--on sale. https://www.brownells.com/gun-...245-charging-handle/

Will fit a Mark 4 bolt. Easy , inexpensive upgrade. $7.75 upgrade versus Tamdemkross $49 charging handle.

The bolt handle size hasn't really proven to be a problem, and I'm afraid to add anything to it at this point as I believe it's existing right on the ragged edge of reliability. I'm afraid to make any more changes since it's finally working!

I'm hoping that maybe the addition of the suppressor will add a bit more backpressure and improve the reliability margins a bit more.

Thank you! I’ve got one oddball mag that causes issues and death jams in my MKIV 22/45.

I’ll try this with that mag.

quote:

Originally posted by Riley:
Thank you! I’ve got one oddball mag that causes issues and death jams in my MKIV 22/45.

I’ll try this with that mag.

Hopefully it works for you...it worked wonders for mine. Be sure to post back and let us know if it fixes it!

So I need to update this since one of the issues has been resolved, and another has re-surfaced.

Since my last post in this thread I started getting light strikes again, so I added the Volquarsen bolt upgrade kit, which included a heavier firing pin and a tool steel extractor. The light strikes are now completely resolved, so that's a good thing. The short-stroking/failure to eject issue is back with a vengance, though.

I took it out a few weeks ago and it was choking on the first round of just about every other mag. I initially thought it might be that the mag spring pressure was creating too much friction for the bolt to overcome on it's rearward travel, as it seemed to be worse with a fully-loaded mag. Annoyingly, it never occurred consistently enough for reliable troubleshooting.

This is what was happening (that's a fired case extracting and trying to eject, not a fresh round chambering):



I figured out that my theory was wrong when I pulled the mag out today and it still did it. It was right around freezing out today, and the gun did it for rounds 2, 3, 4, and 5 as well (single-loading and then removing the mag, as well as with the mag installed).

I stuck the gun and loaded mags under my coat for about 10 minutes to warm them up, and it ran through 20 rounds without a single hiccup. Then I tried leaving the gun out in the cold and warming the loaded mags. That seemed to work ok...only one malfunction in 20 rounds. So I tried warming the gun and leaving the mags cold, which resulted in 3 or four malfunctions.

I'm thinking one of two things (or both) is happening:

1. My lube is thickening in the cold enough to slow down the bolt travel and prevent the round from ejecting.

2. The cold is effecting the performance of the ammo (Federal Automatch) enough that it doesn't have the power to overcome the spring pressure and fully cycle the gun.

FWIW, we took my son's MkII along today and it didn't have a single issue, shooting the same ammo and lubed with the same stuff. We even tried swapping his bolt into my gun, but there were some fitment issues so we couldn't test it (I know a MkIV bolt will work in a MkII, apparently the same is not true in reverse).

I brought it home, cleaned it, and lubed it up with Remoil, which is the lightest and thinnest stuff I've got. I'm going to try and get it out again this week and see if that makes a difference with both warm and cold ammo. Either way I think this thing is running right at the ragged edge of reliability. Anybody else out there fought this particular issue and found a resolution? Am I missing something?

Purely speculation on my part, but I would also take some jacketed ammo to try. I like Automatch well enough for bolt guns and revolvers (I know, automatch in non auto guns...) but I prefer the federal bulk pack jacketed stuff for auto loaders. It seems to feed better, not get as dirty as fast and is generally more consistent round to round from the bench for me. And at the time I was shooting a lot, it was basically a wash price wise when figuring 525 vs 325. All my experience was consistent across platforms as well. A Neos, 3 MKIIIs including a Lite, several 10/22s, gsg 1911 and a 15-22 all ran better on the jacketed bulk pack ammo. Don't remember if 36 or 38 grain HP.

How do you like the TK blast shield vs Volquartsen's hammer bushing? I have a MKIV target I'm trying to decide on parts for.

Cold--its the lube. Bring some CLP to see if that fixes the problem.
Check the red dot to make sure the screws don't interfere with the bolt.

quote:

Originally posted by wolfe 21:
Purely speculation on my part, but I would also take some jacketed ammo to try. I like Automatch well enough for bolt guns and revolvers (I know, automatch in non auto guns...) but I prefer the federal bulk pack jacketed stuff for auto loaders. It seems to feed better, not get as dirty as fast and is generally more consistent round to round from the bench for me. And at the time I was shooting a lot, it was basically a wash price wise when figuring 525 vs 325. All my experience was consistent across platforms as well. A Neos, 3 MKIIIs including a Lite, several 10/22s, gsg 1911 and a 15-22 all ran better on the jacketed bulk pack ammo. Don't remember if 36 or 38 grain HP.

How do you like the TK blast shield vs Volquartsen's hammer bushing? I have a MKIV target I'm trying to decide on parts for.

Yeah, I probably ought to try some different ammo, and the next time I go out to test it I'll take a box of something else. Automatch is by far the cheapest stuff locally, and in bulk from sgammo. It runs perfectly in our MkIIs, and in my dedicated .22LR AR, so while it may be a contributing factor, I'm not willing to blame the ammo outright.

The Volquartsen stuff is head and shoulders above the Tandemkross parts, both in function and fit and finish. To be completely fair, the Tandemkross blast pack was only 3 parts (Hammer, sear, and blast shield) while I replaced just about everything in there with Volquartsen parts, including the trigger and trigger bar. The Volquartsen kit was more expensive, but more comprehensive. The Tandemkross stuff appeared to be more dependent upon coatings, whereas the Volquartsen parts are highly polished steel.

If you're on a budget, the Tandemkross stuff would be an upgrade over factory, if just to get rid of the stupid mag disconnect, but it's absolutely worth spending more for the Volquartsen kit. Get the upgraded firing pin, too.

If you're asking about the ability of the Tandemkross blast shield to keep crap from blowing back into the action of the gun...it doesn't. Maybe it protects it a little bit but everything still gets filthy and it made no practical difference to my cleaning process. For my Mk-Series guns I typically scrub the frames with solvent on a brush and then blow them out with compressed air before oiling.

quote:

Cold--its the lube. Bring some CLP to see if that fixes the problem.
Check the red dot to make sure the screws don't interfere with the bolt.

It may well be the lube, and I'll definitely try a few others if the RemOil doesn't fix it. I think I still have a can of CLP somewhere. Again, though, the MkIIs were lubed with the same stuff as the MkIV, and they ran fine under the same conditions.

Screws are not encroaching into the bolt channel, but that's a good thought.

This is an excellent thread and for me, quite timely. I recently sold my Mark II’s (stainless) and bought a Mark IV Tactical. I haven’t shot the Tactical yet but now I’m even more anxious to.

quote:

Originally posted by TN Mark:
This is an excellent thread and for me, quite timely. I recently sold my Mark II’s (stainless) and bought a Mark IV Tactical. I haven’t shot the Tactical yet but now I’m even more anxious to.

Awesome, it makes me really happy to hear that it's been helpful...that was my primary goal for this thread. Hopefully your Mk IV doesn't require any of the troubleshooting steps that I've gone through. Please be sure to report back once you've had a chance to shoot it!

Yep. I froze ammo, the gun etc. Slip 2000 works great and it was one particular ammo gives me fits, the CCI AR Tactical.

Still need to tweak the mag…

It was doing the ame as your last picture plus the nose up jams.

quote:

Originally posted by Riley:
Yep. I froze ammo, the gun etc. Slip 2000 works great and it was one particular ammo gives me fits, the CCI AR Tactical.

Still need to tweak the mag…

It was doing the ame as your last picture plus the nose up jams.

One thing I have found to reduce the short stroking failures is to put a drop of oil on the top round in the mag and let it run down onto the ones below. That fixes it for the most part, but it feels more like a band-aid, and you shouldn't have to do that all the time. My goal is to get it to where it won't need me to do that.