MK III uppers cracked

Kruzr · Post by **Kruzr** » Fri Sep 04, 2009 4:56 pm

I'm going to agree with Bullseye (keen eyes) that it started around the front locking lug. It does appear to go to (or from) the inside

Nope, the cracks start at the bottom outside where the flat is milled. One has propagated to the inside.

The guns are probably on their way to Arizona today so I don't know if any more pics are possible. I'll stop by the range tomorrow and find out.

While I too would like to know if this is something to expect when the guns get a lot of rounds through them, I can understand the manager's desire just to get guns back in the case.

Gun rentals mean some revenue and more importantly, ammo sales. If you weren't aware of it, ammo sales are the most profitable thing about running a range. It takes about six months to a year to recoup costs of guns by rental fees for the guns. Some guns will have 20K - 30K down them by the time rental fees pay for them. It takes much less time to make that same amount on ammo sales.

Post by **Bullseye** » Fri Sep 04, 2009 5:10 pm

It makes perfect business sense. Just like in the computer industry, the money's in the supplies not the hardware. They practically give away printers just to sell the ink cartridges at a generous mark-up.

R,
Bullseye

blue68f100 · Post by **blue68f100** » Sat Sep 05, 2009 2:59 pm

the cracks start at the bottom outside where the flat is milled. One has propagated to the inside.

I was referring to this area, my mistake on referrance to the lug. It's actually behind it. Fatigue cracks can be very hard to see if the Yield point of the steel has not been reached. It when it's been over stressed is when they are easy to see.

Since I have a MKIII I decided to do an early cleaning so I could inspect mine. I bought mine used, but looked like it was hardly fired. I have only put Std and High Velocity through mine. I tried a few rounds of the Hyper Vel 31gr but my gun did not like it at all.

What I found was indications of High Stress in the same area. You have to look close to see these areas. If this is where the interference fit is, it make sense. I do not have dye penetrant available to see if I actually have a crack. That will have to wait till I go back home in 2 mo. If so it starts where the back of the notch, where it ties both side together. If this is true the LCI may not be the cause. These are the 2 best photo I was able to get to show this area.

I do not know how these parts are assembled to know why this area is stressed. If this is where the interference fit is it make sense.

Maybe Bullseye can educate me....

Post by **Bullseye** » Sun Sep 06, 2009 11:59 am

The Ruger .22 manufacturing process is fully automated. First a finished barrel assembly is seated into a 1" OD, 1/4" thick piece of tubing. Then using the barrel's front sight mounting hole as an index reference point, the tubing is sequentially cut for all the mounting and ejection surfaces. This is why a Ruger .22 Auto barrel is not easily replaceable on a finished gun. A new replacement barrel has to be properly indexed for the feed ramp location. This requires proper barrel torquing and in the final fit the feed ramp must be perfectly perpendicular to the receiver. Since the new receivers are only plain tubing on the production line, the index point references the proper feed ramp alignment and the plain receivers are cut from there. It doesn't matter where the barrel is positioned because the index point is used to make the cuts and the alignment ends up perfect every time.

What you are seeing in the picture is the place where the barrel's feed ramp meets the inner sidewalls of the receiver tube. This is right at the rear edge of the barrel's chamber face. The LCI pin hole has produced a weak point in the tubing, in this critical area, and is absorbing more of the stress as the receiver flexes from recoil. A Mark II receiver tube evenly distributes this stress across the whole receiver surface area, while the Mark III receiver is focusing it into this small area cut out area, causing the stress crack. The metal tubing is substantially thinner where the LCI pin hole has been bored. The LCI slot is acting like a counter bored stop and preventing the crack from propagating all the way around the receiver's tube diameter.

Dyepen may reveal a crack but is subject to the quality of the machining process where Magnaflux might be a better indicator of a emerging crack since it will react better to the properties of the metal.

R,
Bullseye

blue68f100 · Post by **blue68f100** » Sun Sep 06, 2009 4:07 pm

Bullseye thanks for the detail in the mfg process.

On the torquing process, where are the contacting/mating surface(s). And are they using what is know as zero clearance fit?

If these MKIII's starting cracking it will cause Ruger a lot of problems. Just for adding a LCI....... The fix will be easy just remove the LCI and save on that machine time. It causes more problems than good.

Magnaflux only works on ferrus (magnetic) material, the reason I said dye penetrant. But some SS are magnetic and magnaflux will work but most SS are not. I prefer the wet flourscent dies (dye pent or mag) which are more sensitive than dry.

Post by **Bullseye** » Mon Sep 07, 2009 10:34 am

I don't have the production specifications/tolerances for the barrel to receiver mating. I cannot say with 100% certainty what type of fit is used but based on my experience I'd say the mating is a transition fit, otherwise they'd have to press each barrel into the receiver prior to screwing and torquing. This would add considerable time to the manufacturing assembly process as tolerance deviations would make barrel to receiver mating a time consuming process. Plus based on production deviations, the barrel torque value readings would widely vary based on individual part dimensions.

You also bring up a good point. If the parts tolerances are more of a zero clearance fit then the properties of expansion would also stress this particular area as these two components heat at different rates. The barrel assembly heats faster, as it is more directly affected by projectile friction than the receiver tube, and would have a greater expansion rate than the tube.

I suggested Magnafluxing because the stainless steel grade used in Ruger's firearms is ferrous. Either technique would work and Dyepen is the least expensive to use.

R,
Bullseye

Georgezilla · Post by **Georgezilla** » Mon Sep 07, 2009 1:39 pm

Very interesting... It's funny, to understand Blue and Bullseye's posts, I've been having to google about every 4th word

blue68f100 · Post by **blue68f100** » Mon Sep 07, 2009 3:07 pm

Georgezilla wrote:Very interesting... It's funny, to understand Blue and Bullseye's posts, I've been having to google about every 4th word

My 30yrs in material testing is showing. I had the benefit of working with Material engineers and researchers most my life. At one time I was a level 2 tech in all non destructive testing process except ultrasonic. I also got into stress analysis on a lot of things which included strain gages, lacquers and modeling/polarized stress. This one was done is several different ways. But mostly we made parts to scale out of special plastic, and used polarized lighting to see where and how the stress was distributed. But I also did a lot of distructive testing too. This was the fun part, after doing all the test we could without tearing up the part, the last test was to take it to destruction. Now I must say not everyone like this part due to posiable danger. I always looked forward to it, it's nice getting paid to tear things up. Some of our well head valves held about 1 cuft of gas. That volume at 30k psi = the shock wave of 5 sticks of TNT. I had specially design test bunkers for this type of testing. Plus one was design for gas containment just encase I was using corrosive gas mix, hydrogen sulfide/carbon dioxide mix. Yes, a lot of my testing was with toxic gases, acids, and caustics that was the bad part. But I was big on doing thing the safe way and did not cut corners when safety was involved.

Bullseye, Thanks for all the info. I was just interested in getting the facts so I could fully under stand how the stresses were distributed. As usual your knowledge is remarkable when it comes to these guns.... Which I think benefited all.

Post by **Bullseye** » Mon Sep 07, 2009 5:36 pm

Well in light of your vastly extensive NDI material testing experience I would have to defer to your expert judgment. My experience in the field of non destructive research product material testing is far less. I think we can both agree that without an actual specimen to examine all we have is speculation as to the casual factors of this failure. I really do appreciate your contributions to this discourse on cracked Ruger Mark III receivers as it has made for one interesting discussion on metal fatigue.

R,
Bullseye

blue68f100 · Post by **blue68f100** » Mon Sep 07, 2009 10:23 pm

Bullseye, I too have enjoyed this thread. We all have learned something from it.

The only problems is that something I don't use probably got purged. My wife calls this old age. I disagree.

I just wish I had access to all of the test equipment I use to run. I think a high power x-ray machine could tell us a lot on how the barrel fits the receives. X-ray gives a better resolution than gama ray, smaller focal source. But the cost of having this test done is out of my budget. Ultrasonic may tell us if they have a near zero interface.

I use to have fun with engineers when it came to predicting results. Most all only had book knowledge, vs my real life experience. My boss always ran new engineers through my labs. Some for training and other for evaluation. He wanted me to access how they tackled and solved problems, whether they had any common sense. A few times I had to stop them from doing something stupid and killing themselves and other. With the toxic gases I used you really had to be careful. One breath at a lethal level would take you down and out. Most had the notion that they could smell the gas and get away, which is very wrong at lethal levels. I carried a personal gas detector on belt daily, I knew I could not smell it. I must admit it saved my ass more than once. Then the safety dept recruited me into the HAZMAT team. I ended up being a Level 4 tech, Incident Commander for our site.

raw6464 · Post by **raw6464** » Tue Sep 08, 2009 5:19 pm

From the MKIII-2, I see a lot of wear on the bottom of the barrel where it sits on the frame... and indication of a tight barrel to frame fit.

So the barrel is "stressed" at two points in the front... where it rests on the front of the frame (where the wear is) and also at the lug which acts as a "pivot point" if you will.

It is conceivable that the force of the frame "pushing" up on the barrel, and with the lug acting as a pivot point, the expansion hot/cold cycles cause the barrel to crack because it has been compromised by the slot cut into it from the LCI and the heavy use as a rental?

And then again ... I could be all wet!

Post by **Bullseye** » Tue Sep 08, 2009 9:36 pm

raw464 wrote:It is conceivable that the force of the frame "pushing" up on the barrel, and with the lug acting as a pivot point, the expansion hot/cold cycles cause the barrel to crack because it has been compromised by the slot cut into it from the LCI and the heavy use as a rental?

Your hypothesis is just as valid as any other that has been brought up throughout this discussion. It could very well be compounding physical factors that caused these Mark III frames to stress crack.

R,
Bullseye

Post by **Bullseye** » Tue Sep 08, 2009 9:48 pm

blue68f100 wrote:I just wish I had access to all of the test equipment I use to run. I think a high power x-ray machine could tell us a lot on how the barrel fits the receives. X-ray gives a better resolution than gama ray, smaller focal source. But the cost of having this test done is out of my budget. Ultrasonic may tell us if they have a near zero interface.

I must agree. I too wish that I had a good failure sample and some of the equipment at my disposal as I did a few years back. A portable ultrasonic scanner or ultrasonic microscopy unit would reveal the joint much better. Radiographic analysis would be another option but as you point out it's on the high side cost wise. Of course my NDI technicians could have always used something like this as a practice piece for their quarterly RAD inspection qualifications.

R,
Bullseye

raw6464 · Post by **raw6464** » Wed Sep 09, 2009 11:10 am

Bullseye wrote:
raw464 wrote:It is conceivable that the force of the frame "pushing" up on the barrel, and with the lug acting as a pivot point, the expansion hot/cold cycles cause the barrel to crack because it has been compromised by the slot cut into it from the LCI and the heavy use as a rental?
Your hypothesis is just as valid as any other that has been brought up throughout this discussion. It could very well be compounding physical factors that caused these Mark III frames to stress crack.

R,
Bullseye

Well whatever the root cause, this is not good considering the probability of 3 guns cracking at the same place.

If there's a problem with a particular lot that's one thing... if it's systemic through out the entire MKIII line... well let's hope that's not the case.

EDIT:

We won't know what Ruger has to say since all three are going back to Davidson's and will be replaced under their replacement warranty. The two MK III's were manufactured in 2005 and bought in 2006. The 22/45 was made and bought in 2006.

After reading back... since the guns where made a year apart a particular lot is improbable.

blue68f100 · Post by **blue68f100** » Wed Sep 09, 2009 2:54 pm

Yes it does not look good, there may be a recall in the near future.

How ofter was the recoil springs replaced?

The reason I ask my neighbors MKII had never been replaced and it was super easy to pull the bolt back. When he tried mine he could not believe how hard it was. I have ordered him a replacement recoil spring.

btw. What is the recommended round count to replace the RS?

Sig's are normally 5000 rounds or when the center wire (wire wrap springs) extends 1/4", Browning HP are around 1500 rounds..