A friend's 1917 Enfield (coned breach) blew up on him. 7mm STW, fired 3 rounds with one bullet/powder combo then one round with same powder but differnt bullet of same weight which blew. Both primary lugs sheared but safety lug on bolt handle held. Unscrewed bbl to find that the belt headspaced on back of barrel. Chamber was not cut deep enough for belt to be inside the chamber. Maker said he did it that way because customer supplied P14 extractor. Blow up could have been caused by any number loading mistakes, but I think the chamber should have been cut deeper and P14 extractor should have been modified. Any thoughts?

What's the purpose of the belt? Besides providing some reference for headspacing?

The belt is designed to fit inside the chamber. My chamber print for the STW clearly shows the belt cut as an integral part of the chamber. All my belted magnum reamers are designed to incorporate the belt as part of the chamber.

Well here's the deal. Anytime you vier from established procedures you incur all the risks involved.
Now the chamber may or may not have contributed to the blow up but it was definitely not performed correctly.
He may owe your friend a new gun

quote:

Maker said he did it that way because customer supplied P14 extractor.

Crazy! And a lame excuse...as surely for a "wide" diameter case such as a 8mm Remington Magnum a P '14 extractor is the correct one to use anyway?

Back when I messed with P14/1917 Enfields, it was common practice to use either receiver, P14 bolts, 1917 extractors, followers and mag boxes for magnum conversions. There was a whole lot of case unsupported here.

I'd also like to see the difference between a P14 and a 1917 in the extractor area.
I haven't seen either in a while so not sure but a pre 64 M70 has a cone breach and that rifle is chambered for belted magnums. I really think that smith was not competent in what he was doing.

I am not a smith, so please be kind, but is a P 17 really strong enough for a STW?

Have been building my own rifles since 1969--
(Not a smith by profession.)

Have never left a magnum belt hanging in space unsupported--
and/or headspaced a belted round off the shoulder;
nor have I seen it done by the smiths I know or have worked with.

No bolt action is strong enough if chambered that
stupid way. Good Lord. Once a case blows through it isn't
a gun anymore it is bomb.I've put most all of my
wildcats in Enfields and they do fine.And they are
much harrier than STW.Ed

quote:

Originally posted by Moorepower:
I am not a smith, so please be kind, but is a P 17 really strong enough for a STW?

Should be, if properly done.
I did have mine re-heat-treated,--
the bad reputation came from the Eddystone production-- which supposedly had poor heat-treating.

Certainly both P-14s and P-17s are strong enough for belted mags, if not flawed. I have owned and used .450 Ackley Mags based on both.

When I first got them I followed Ackley's loading advice (90 grs IMR. 3031 and 500 gr. Jacketed bullet). The gun held together fine (it was a P-14), but the brass was only good for one shot at that pressure level. Dropping it down to where brass life was practical, I found Ackley's load was about 15 grains (!) too high, except in my particular P-17 where it was almost 18 grains too high...... Needless to say, I never went to the 90 grain load again after the first time.

Seems to be a consensus here. Thanks for the input. Dan

The actions are certainly strong enough if properly smithed, reference the A-Square series of cartridges that were originally developed on these actions.

Leaving the belt unsupported is certainly incompetent and an invitation to a sidewall blowout of the case. This failure typically would release gas back into the action, almost certainly blowing out the magazine and splitting the stock.

However I can't quite visualize this blowout failure causing the broken bolt lugs. Splitting the receiver ring yes, but not breaking the bolt lugs.

I suppose if the receiver ring split, then the support for the lugs might momentarily shift onto only the outer edges of the lugs, thereby greatly increasing the shear load due to the different angle. The forward positioning of the lugs on the 1917 bolt body, as compared to the 1898 Mauser's slightly more rearward positioning of its lugs, means the 1917 lugs are peculiarly subject to failure under an outboard-applied and inward-slanted vector force. BTW this slightly rearward positioning of the 1898 Mauser's lugs behind the bolt head is yet another one of the Mauser's superior design features. Food for thought.
Regards, Joe

Whoever built that rifle is incompetent. The improper headspacing caused the blow, that is what bad headspacing does.

Well there you go
I think I'd ask him for a check for the full replacement value of the rifle. And if that doesn't work maybe some legal action as this kind of incompetence could get someone killed.
And BTW a good friend of mine has a Remington mod 30 which is a copy of the 1917/p14 Enfield it was chambered for 30-378 by Roy Wheatherby back in the early 60's before it was a commercial cartridge so yes the rifle is quite capable of handling the pressures of an STW so long as the belt is seated inside the chamber

If the case split due to having belt out of the
confines of the chamber, maybe the bullet only moved enough to be a stuck obstruction, then
the full force of all that powder and gases
impinging rearward on the bolt cracked the lugs.
And if the bullet made a temporary obstruction in this
type of setup then the speed of the explosion may have
been like the SEE effect, in that the powder went to
explosive speed, which much faster than when the powder
has a controlled burn acting as a propellent like it is
supposed to. And no gun can stand powder burning speeds
in the explosive speed ranges, ike 20-30,000 fps.
Propellants work safely at about 5000 fps.
Thank goodness for the heavy bolt handle base as a
safety lug.Ed

A bolt shedding it's lugs is very rare.
A few early Weatherby's did, but I have never
heard of any others.
Could someone post a picture ?.
Good Luck!

A little bit off the subject here but this kind of touches on one of my pet peeves and that is the coned breech. I don't care for the way most of these barrels are finished in that area. It seems that the most popular way to finish this taper is to continue it past the front of the bolt face until it runs out into the chamber. This gives a very smooth and continous path for the nose of the bullet to enter the chamber. This also relieves the chamber just in front of the bolt buy up to .060 depending on the angle of the cone and how much clearance is allowed between the angle of the bolt and the angle of the cone. This removes any material that might be helping to support the belt in the case of a magnum and depending on how sloppy the machining on the cone is, it could possibly remove all the support for the band. I've seen people have trouble with the Tubb 2000 (a match rifle) blowing cases and have often wondered if this might be the problem but haven't had my hands on enough of them to determine yes or no. Since I haven't seen a bolt that was tapered all the way across the front into the case head recess, what I prefer to do is to machine the cone parallel to the bolt front approximately .010 in front of the bolt face and then begin the cone taper once I get outside the bolt front diameter. This adds a square shoulder of roughly .110 (about .720 diameter), in the case of a .308 bolt face, at the end of the cone, but I've never had a complaint about feeding, ever. What this does give me is an unsupported area of only .010 to .015 between the bolt front and the back of the chamber. I believe that this is the safest way to do a cone breech without giving up any of the smooth feeding characteristics of the cone breech. Anyone follow what I'm trying to say here?

quote:

Originally posted by J.D.Steele:
The actions are certainly strong enough if properly smithed, reference the A-Square series of cartridges that were originally developed on these actions.

Leaving the belt unsupported is certainly incompetent and an invitation to a sidewall blowout of the case. This failure typically would release gas back into the action, almost certainly blowing out the magazine and splitting the stock.

However I can't quite visualize this blowout failure causing the broken bolt lugs. Splitting the receiver ring yes, but not breaking the bolt lugs.

I suppose if the receiver ring split, then the support for the lugs might momentarily shift onto only the outer edges of the lugs, thereby greatly increasing the shear load due to the different angle. The forward positioning of the lugs on the 1917 bolt body, as compared to the 1898 Mauser's slightly more rearward positioning of its lugs, means the 1917 lugs are peculiarly subject to failure under an outboard-applied and inward-slanted vector force. BTW this slightly rearward positioning of the 1898 Mauser's lugs behind the bolt head is yet another one of the Mauser's superior design features. Food for thought.
Regards, Joe

The whole problem with unsupported casehead is that when the casehead ekspands radial, the presurearea inside an intact case increases from apx 1cm2 up to the whole frontarea of the bolt, often more than 2.5cm2. That is the reason for the frontlugs beeing sheared of.

During a series of blowup tests we performed, the safetylevel of all actions with CRF was way lower than PF actions.
Mauserdesigns suffered sever damages from 50% of the presures that PF rifle handled without letting go.
It all started when the casehead lets go.


I guess that this gunsmith excuses himselve with the standard excuses "I have seen it done manny times, and i have been dooing it for long, without any problems so i thourght it was safe, because i have never had any problems"

quote:

During a series of blowup tests we performed, the safetylevel of all actions with CRF was way lower than PF actions.

I would like to read about your test; is it availible anywhere?

Ackley took a P-series (IIRC) and fit a 270 barrel to it. Then chambered it in 35 Whelen and fired some hi-pressure loads thru it. He wrote that the 250gr bullet came out about 2" long, but otherwise okay.

I'd have to watch (from far away on camera) to see someone blow one up built properly. AS pipefitter masquerading as a gunsmith; now that is something else.

Rich

I would be interested in seeing pictures of the failure, as well as the improper head space condition. I hope no one was hurt.

quote:

Originally posted by DuggaBoye:
Have been building my own rifles since 1969--
(Not a smith by profession.)

Have never left a magnum belt hanging in space unsupported--
and/or headspaced a belted round off the shoulder;
nor have I seen it done by the smiths I know or have worked with.

I chamber all my belted mags to head space off the belt. Having done that, all my reloads head space off the shoulder for that particular chamber. Belts vary from case to case. Once the chamber is set I then resize to fit snug in the chamber by shoulder contact. It's safe and closer fit. In no way ever chamber short enough to leave the belt out of the chamber. That's asking for a face lift on the light side and maybe even death on the severe side. Chamber by the book then fit case to the chamber.

Gentlemen,

I have been reading this thread for the last couple of days. It seems to me that the reason for the failure would lie with the barrel shank being too short. With the cone properly cut, but in a short shank would leave a lot of the case sticking out of the chamber. Hence, a blow up. If the shank and the cone were properly cut, the headspace gauge would gauge on the belt as it should be. The bolt would not close on the go gauge. My belted magnum headspace gauges and all that I have seen, have a very short shank and the belt with a little shank above the belt. Am I right or wrong in my assumption as to what happened.

I do not understand the relationship of the different extractors. I cannot see why one would want to use the Pattern 14 extractor for a rimed cartridge when chambering for a rimless round. Someone please enlighten me.

Muchas gracias,
Hoot

Hoot
not a smith, but I'll take a guess.
The M-17 extractor hook is longer (for the .473 case head), while the P-14 extractor is closer to the correct length for the .530 "magnum" case head

no pics yet?

quote:

Originally posted by Hoot Murray:
Gentlemen,

I have been reading this thread for the last couple of days. It seems to me that the reason for the failure would lie with the barrel shank being too short. With the cone properly cut, but in a short shank would leave a lot of the case sticking out of the chamber. Hence, a blow up. If the shank and the cone were properly cut, the headspace gauge would gauge on the belt as it should be. The bolt would not close on the go gauge. My belted magnum headspace gauges and all that I have seen, have a very short shank and the belt with a little shank above the belt. Am I right or wrong in my assumption as to what happened.

I do not understand the relationship of the different extractors. I cannot see why one would want to use the Pattern 14 extractor for a rimed cartridge when chambering for a rimless round. Someone please enlighten me.

Muchas gracias,
Hoot

Believe it or not, as Ripley used to say, many 'smiths seemed to think the opening of a boltface and modification of the extractor was a daunting task. At least, this seems to be the case. So, they mixed and matched to avoid these scary chores.
In this particular case, it seems the gunsmith was reluctant to modify the P-14 extractor and unwilling the make an extractor cut. Not good. Regards, Bill

On my 585 Belted case and 550Mag belted in the Enfields here
I use the P14 extractors by grinding off the front of
them so that they have 5-10 thousands clearance from a flat barrel
end.They work fine and no coned breech needed and all of the
belt of the cases is inside the barrel, When grinding these off
go slow and keep them cool so that the hook isn't softened.

On an Enfield if you want to buy ready made extractor for
H&H mag bases cases just buy a 77 Ruger one from G-Parts.
The one from my Ruger 77 fits on Enfield ok.

Either way easy way to do it. It is easier to grind some
off front of a P14 one, than to grind out the diameter on a M17
one and no extractor cuts into the barrel.Ed

Just for everyone's info, the coned breech is certainly not necessary and can easily be eliminated during any rebarrel. Sure makes things a lot easier albeit no longer completely as-designed. This is true for all the coned-breech actions, it's just unnecessary work in most cases.
Regards, Joe

I remember the elimination of the coned chamber on Enfields and Springfields being referred to as "safety breaching".