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Discussion Starter #1 (Edited)
Since reloaders often have quite a few questions and opinions about maximum pressures, I thought this would be interesting to see. This is an extreme example, but it is reasonable to ask: "How badly do you want to be a velocity pioneer when going beyond the known territory of the gunmakers and the powder manufacturer recommendations?"
The attached photo is of a 44mag Thompson Center Contender (a really sturdy gun) that an 'expert' customized by drilling the chamber another inch longer to turn it into a .444 Marlin. YES, that is an extreme increase in powder. The owner reported that on the 38th shot the Contender had a life-changing event. The shooter felt lucky that he only needed 30 stitches of repairs on his hand. Now the Contender chamber can hold a cartridge about the diameter of a water balloon! Photo attached. Click on the 444 Blowup link just below this.:eek:
 

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The Hog Whisperer (Administrator)
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Interesting, any idea what loads were being used? A .444 is only slightly larger at the base than a .44 mag, and standard pressures for each are pretty close. As I understand it the .444 is a standard chambering for the Contender as well..... so I'm surprised that a reasonable .444 load would blow it up.
 

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Mike G,
I don't see the .444 listed at SSK Industries, Bullberry, Fox Ridge, or Virgin Valley barrels. These are four of the big custom barrel makers, so I'm guessing it's not safe in the TC. The 444 is a higher pressure round that the 44 Mag or the 445 Supermag and they all have approximatley the same case head size. On top of that, this loader may have been exceeding loading data for the round. The pressure limit for the 444 is 44K, the 44 Mag is 36K. There is no listed standard for the 445 Supermag, but I've seen it listed with 41-43K. All this would really take is a overload. The barrel could have had throat erosion before being rechambered, as this guy was obviously an experimenter, which would have possibly weakened the metal in the end third of the 444 chamber. The chamber could have been cut short, the chamber could have been cut too tight. There are a lot of problems that can arise when you don't know what you're doing, this picture is proof of that. Luckily the experimenter came away from this with the use of his hands and eyes.

Note to home gunsmiths:Successful people who do this for a living know more than you do, follow their lead when determining safe cartridges for the Contender or Encore.
 

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Discussion Starter #4 (Edited)
Mike G -
I don't know the details of the load used. I took the image off a web site, and web sites can be less than reliable. But there were quite a few photos of this gun, including the twisted remains of the scope and scope rings, and the shooter named the name of the gunsmith. I am not repeating the name, since I don't know the whole story.
Here's a thought: not only does a max load 444 have more pressure than a 44 mag, perhaps the lengthened case may have been more directly positioned under the scope ring mounting holes, which would be a weaker point than solid metal. Notice the barrel split right down the top, then split along the sides where ie was mounted hard on the frame. Just guessing. I don't have a Contender here to look at.
 

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I think the answer to this question is found in the statement by Greenhorn Dave, that the experimenter had "drilled out the chamber". If you look closely at the front of the chamber you will see that it is extremely rough, as if a drill had been used instead of a reamer! He could easily have polished the rear of the chamber to enlarge the base and allow seating a .444.

The listed SAAMI pressure limit for the .444 is lower than the original standard for the .44 Magnum which was, as I have seen published, 46.000#, so that shouldn't have been the problem. The .44 Mag is proofed at higher pressure.

What I believe was the cause of this blow-up is one of, or a combination of these things. (1) The front of the chamber is too small in diameter, (2) The chamber is too short, (3) The ammunition used were handloads which were loaded to much higher oressure than SAAMI for the cartridge. It is unlikely that standard oressure for the .444 alone would have this result since this gun is chambered for other cartridges developing higher pressures. (2), (3), or a combination of the two are the most likely culprits. It is hard to tell from the picture, but it doesn't look like there is any throat, either. Even though the barrel split through the screw holes, this is common. Even had the holes been drilled into the chamber the only result would probably have been ruined cases. Basically, from this picture, this is a classic over pressure blow-up most likely caused by a severe overcharge, deliberate or not.

Bottom line is that this dummy didn't know what he was doing.
 

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Discussion Starter #6 (Edited)
Maybe this will help.
Attached is another photo that would support the theory that the scope mount holes were part of the problem. Note the scope mount holes. I can see CB Hunter's point about the screw holes, but I can't ever imagine just blowing out some screw holes. A lot of things hold together pretty well until a weak spot begins to tear apart. The recent space shuttle tragedy is a example of that.
In any event, there's a lesson here someplace. I remember someone once telling me that some of the least painful lessons come from paying attention to someone else's experiences.
 

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Alk,
the basis for safe chamberings in the Contender are based not only on pressure but case head size. The .223's and wilcats based on that case have a small head size. The cartrideges based on the 30-30 have to remain within the specs for the 30-30 pressure or a little higher. The 45-70 is only permissable with trapdoor level factory loads. The 444 is not a standard or custom chambering in the Contender. I think that they used a reamer on this, not a drill bit, but I'm not sure because of the picture. There appears to be a throat at the front of the chamber which would preclude using a drill bit. It's hard to tell from the pictures though.

Dave,
The screw holes for the rear sight on a Contender barrel are the same ones used to mount a scope. They would be over the chamber of most any cartridge used. I don't doubt that the holes contributed to where it let go, but I wouldn't call it the cause. The fact that the barrel was chamberred for 444 and the likely fact that the pressure was upped a bit are the likely cause for this problem. As I said previously, the chamber may well have been short also. Using shade tree gunsmith rules,we'd chamber using a loaded round as a headspace guage, no sense in getting the proper tools for the job. After all, it headspaces on the rim, so if it fits, it's safe, right? Not right. If a loaded round, with a healthy crimp, was used to determine the chamber depth, the pressure of a factory round that couldn't properly release the bullet because the case mouth was forced and held into the bullet by the throat, could cause signifigant pressure increases. Perhaps enough to make the barrel give up the ghost after 38 rounds. Just a theory, but it would be one possibility.
 

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Discussion Starter #8
kciH -
I see what you mean about headspacing on a crimped cartridge rather than using the right tool, a headspace guage, for the job. I can tell you this: I have the greatest respect for the huge power that can come out of a small brass case, and for gunsmiths who really know what they are doing.
This is not a good hobby for careless or 'by guess and by gosh' people.
 

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Dave,

That does show the holes better, but that isn't uncommon in many installations where the barrel is drilled for scope or sight mounting. Even if they had been drilled completely into the bore, it wouldn't be likely that even a screw blow-out would occur if the screws had a normal engagement. What I saw and referred to in the original post link was apparently a tear in the surface metal over the chamber area as a result of the blow-up rather than a screw hole. It is difficult to explain, but if it were possible for a small hole, like those drilled for sight mounting, were able to weaken the barrel sufficiently to allow such a failure, then guns would split at the muzzle, and cylinders would split at the front of the chambers. A cylinder stop cut in a revolver cylinder weakens it much more, and and in a high pressure area, and cylinders only fail if an extreme overload is imposed. And cylinders typically have a cylinder wall much thinner than this barrel wall in the chamber.

Further, I assume (yes, that can be dangerous) that the screw holes were the original cut by Thompson-Center in the barrel. The barrel would have accepted proof pressures higher than what is normal even in the .444 with these holes, again with the assumption that the gun had been drilled & tapped for a factory sight.

Just to give you a little background, I, among other things, am a trained gunsmith who has worked in several shops and for a major reloading tool manufacturer. One thing we did as an educational experience while in gunsmithing school was to blow up rifles deliberately to see what they would take. It is amazing how difficult this is to do!

One gun we blew-up was a Lee-Enfield, an action considered to be relatively weak. It was re-chambered to .300 Winchester Magnum!!!!!!.. Over the case shoulder the barrel was only about 3/32" thick, and the gun was fired several times with factory loads which develop about 11,000 psi more than even the .444 Marlin. Handloads were tried with a common powder for the .300 Mag, even to the maximum the case would hold which was considerably more than a listed maximum. It still took a very heavy load of a powder much faster than appropriate for the cartridge to blow it up, and failure began, not surprisingly, at the thin area over the shoulder of the case. As I recall now, 40 or so years later, the load was 30 grains of Bullseye.

The second factor entering into my evaluation, even though based on minimal evidence, is also based on experience. Most failures such as this one, if caused by a minimal overload such as one causing only a 20% over pressure situation would normally result in a progressive loosening of the barrel locking mechanism and possibly a stretching of the guns frame which would be evident to the shooter, and even be likely to cause a sufficient headsace problem to the point that the gun would mis-fire as a result of the firing pin not being able to reach the primer to ignite it. This event shows all the classic signs of being a one-time event being of such magnitude as to be immediately fatal to the mechanism.

My point is that I speak from both a theoretical and practical position having had experience in this field, and this specific question. I stand by the assessment that this was caused by an extreme over pressure event caused by an overload, tight or short chamber, or a combination of the two, and most likely only an overload. Had the other situations existed to any degree sufficient to cause such an event, loading the gun would have been difficult to the point, probably, of being impossible to load or close it.
 

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Discussion Starter #10
Those are some thorough answers!! Thanks, guys. I learned something.
 

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Hi, Gents:
Just wondering if the extreme roughness of the drilled out throat contributed. Assuming a serious overload, the bullet may have obturated in the throat and gripped enough to add another 10K pressure, instead of sliding through.

The most seriously blown gun I've seen was a Lee-Enfield, No.4 Mk.I. The top of the chamber, ahead of the receiver ring, was gone. They'd hammered the bolt halfways back, but the receiver was bent so bad that the firing pin lined up with the top of the bore, looking in from the muzzle. The extractor and the extractor boss on the bolthead was gone. I wouldn't want to be in it's way when she blew. The bottom half of the case was still in the chamber.

This gun was one the provincial Hunter Safety people had, but nobody knew it's history. We noticed a bit of welding on both sides of the blow-out. The issue peep sight was missing and we speculated that some clown welded a piece of 1/4" stock for a rear sight onto the barrel flat above the chamber and ruined the temper of the barrel steel. Unfortunately the gun disappeared during an office move several years ago.

A couple of gents working at the RCMP depot in Regina got orders to destroy a P14 Enfield in 7mm Remington Magnum. They stuffed a case with Unique, seated a 175 grain bullet and fired it with a looonnngg cord. There was no external sign of damage, but they couldn't open the bolt.

Bye
Jack
 

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The Hog Whisperer (Administrator)
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I guess I somehow got it in my head that .444 was a standard Contender chambering, guess I got it wrong (must have been Ray's fault since I know I heard about his .444 contenders!). Anyway, from what Marshall has reported with his .444 writeups, the Marlin rifles tend to have a very short throat (my .35 definitely does). So, short throat by itself would probably not be the cause, but a short chamber could well cause serious problems, no doubt.

I agree with the comparison of the screw holes to bolt cuts in a revolver cylinder, shouldn't have caused the problem. I did recently read an article in Machinist's Workshop by Steve Acker, well known gunsmith, suggesting that a minimum of 0.100" of steel be left over the chamber when drilling scope or sight base holes. While it's difficult to claim a precise measurement from the photo, it does appear that there is plenty of metal left at the bottom of the holes. Anyway I will double-check the article, hey, don't want to be wrong twice in the same thread!

The front of the chamber does look quite rough, perhaps not quite as bad as standard Ruger Blackhawk chambers these days..... but definitely doesn't look right.

I vote tight/short chamber, and overly enthusiastic reloading.

Also, one other thing, I've seen pictures of rifles blown up where the wrong cartridge was known to be inserted, or a bore obstruction was verified. They basically look the same... barrel and/or receiver split to pieces. So.... could have been a bore obstruction, although it's hard to imagine someone missing that with a single-shot.

Just goes to show, there are few ways to do it right, many ways to do it wrong.....
 

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JDJ chambers for the 430 JDJ which is essentially a 444 Marlin case shortened .1". This was supposedly done so factory rounds could not be fired in the chambering. Evidently, the earlier 444 factory rounds were a bit on the "warm" side.

As this JDJ chambering dates back to the late 70's or so, it's a plausible theory though I think myself there is more to it such as the control of proprietary cartridge name and chambering.

I'm currently on my second 444 Marlin Contender barrel and from the look of these pictures, I'm inclined to say this is a catastrophic overload as Alk states. I really doubt this was done with factory ammo. Unless, this was a defective or overloaded factory round. Unlikely but, anything is possible.

Case diameters aside, don't forget the huge amount of 444 Marlin cased wildcats out there that are chambered in Contenders. I seriously doubt these can be thought of as unsafe. They have been used safely for very many years.

Look at the 375 Winchester, here is a 53,000 CUP round chambered for the Contender. Granted, it's not the same diameter but it is not much less than your Marlin case and it's running 8 to 10 K or so more pressure. I doubt even a mild overload in a 444 Marlin would be enough to cause the Catastrophic failure shown in the pictures.

You are more likely to pound the frame into an early retirement loading a bit too heavy than you are to cause a catastrophic failure like this.

This is why, I'm more inclined to think this was a dangerously overloaded round.


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The Hog Whisperer (Administrator)
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So Ray.... any comment on what happened to your FIRST .444 barrel....????

Just kidding....
 

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Always the "Jerry Lewis" Mike!:D


It was the 12" Hunter version which is essentially a 10" usable barrel length. A bit innefficient for the Marlin and among other things in a fit of irrationality, I sold it to a nice gent in OK.


The current one is a 14" braked version in Stainless.

Nice little beltgun.;)


Regards
 

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Contender,
Who made your barrels? I'm just curious because I don't see it chambered by the barrel makers I'm familiar with. I thought it was a factory TC barrel at one time, but I have been unable to find it anywhere. It seems like it might be a handful in a Contender.
 

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The first one was a Bellm re-chamber of a factory 12" Hunter.

My current one is a VanHorn re-chamber of a 14" Hunter.

Both are very good work with the edge for workmanship/service going to Bellm IMHO.

The custom shop chambers for 445 Super in the Contender with the 444 in the Encore.

Yes it is a handful, about the maximum horsepower I'd get involved with in the Contender. More versatile than the 45/70 chambering.

More of a fun round to me but used quite successfully on big game by others in handgun form.


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Does anyone have a picture of this guys stitches? Can you imagine if this unfortunate person would have been in a creedmoore position, what his leg would have looked like?
 

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Looked over the pictures, and have to come down on the side of a poorly reamed chamber as a likely caurse. Not only looks a bit rough, but looks as if there was no "lead" or "throat" (or whatever term you want to use for the transistion between chamber and rifling).

Pressure shouldn't have been too high for the Contender frame...at least not high enough toblow it, may be high enough to eventyally but shouldn't have let go under normal pressure.

Could havbe been loaded to above normal pressure, which would have blown even a well chambered gun, or forced to be over pressure by the roughness/shortness of the throat.

Whatever the cause, chamber related or reload related, pressure whent through thr roof on this one shot, ans it let go at the thinner section.

Do remember when one custom maker first came out with really big garrels on contenders (including the 50/70) he either (1) would NOT to tap them for mounts and supply just iron sights or (2) had the mount welded to the shaped barrel blank before rifling and chambering.
 
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