Channeling P. O., Mauser blow up project

[copperlake]

Been following this as well. Nice work.

Have you measured headspace after firing those loads? I for one would love to know your "before and after" headspace measurements. Looking for lug setback after de-barrelling the action is a good idea as well.

shredder, I don't have any headspace gauges, I used the tape method. I know you can read all you want about how horrible that method is but in this situation, with the control I have, I believe it's as valid enough. When I put the components together I had to remove some off the barrel face and a little off the left locking lug to get the bolt to close with very slight resistance on three different batches of REM 8mm ammo. All of these loads I fired today chambered the same way, a little resistance. I Took a dental tool and ran it against the locking lug buttresses and cannot feel a ridge. We'll see, some more high end torture and I'll unscrew the barrel. Also, when you look at these fired cases one would say that it has a tight chamber; there is no undo bulging towards the head of the case. You look at them and say, "that looks perfect". The action had no set back when it started out.

I do wish I had more tools to make this a more fruitful effort. ANYONE OUT THERE WANT TO LOAN SOME HEADSPACE GAUGES ? I'll pay shipping.

[fouronesix]

The reason I ask about the QL pressure predictions is that almost all if not all primers will show obvious flattening (assuming more or less correct headspace) at somewhere around 60Kpsi. The QL pressure prediction for test #1 is somewhere around 80Kpsi and that primer does not look like it was subjected to anywhere near that pressure. And it wasn't until #3 that "high" pressure becomes obvious but that is QL predicted at somewhere around 92-3Kpsi.

[copperlake]

The reason I ask about the QL pressure predictions is that almost all if not all primers will show obvious flattening (assuming more or less correct headspace) at somewhere around 60Kpsi. The QL pressure prediction for test #1 is somewhere around 80Kpsi and that primer does not look like it was subjected to anywhere near that pressure. And it wasn't until #3 that "high" pressure becomes obvious but that is QL predicted at somewhere around 92-3Kpsi.

fouronesix, I'd bet on the headspace being correct. I cannot account for your observations. I do know that the Powley computations are theoretical and subject to vast variation caused by seemingly small differences. Again, I hope someone more knowledgeable chimes in.

[DCM]

QL pressures and primers.

QL is a computer simulation model and cannot be used to determine actual pressures Period, From my experience with QL it has been very accurate in predicting other things I can actually measure like velocity and less scientifically weather a powder is completely burnt before the boolit leaves the barrel. The latter promotes less needed cleaning and less muzzle flash.
There is a strain gage tool available for determining pressures that is on my Wish list, but from what I understand it will only give relative pressure not actual. The cost is ~$500 so it won't happen any time soon.

Primers: There are a number of cartridges that are designed to operate over 60,000 PSI.
IME Federal primers have Very soft cups and will flow and pierce much easier than others.
I have pierced a number of federal primers over the years especially pistol primers in warm to hot loads.
I was on the firing line with a friend during a rifle match in which he did something we had done for years with M1As/M14s, we were firing the offhand stage of the match, he had the muzzle of his rifle on his shooting stool pointed toward the ground, he dropped a round in to the chamber and closed the bolt BOOM! the combination of inertia, the floating firing pin and the soft primer cup set off the round!
He was Extremely lucky that he did not shoot himself in the foot, blow up the can of adhesive in his shooting stool and the there were not large rocks below to blow up or for the bullet to ricochet off of!
We are also very prudent about keeping the muzzle pointed down range for all of the above now.
Some fellow reliable and honest shooters from the flatland (ILL.) did a test with small rifle primers and found Rem. primers to be much less susceptible to this type of problem leading us to believe the have much harder cups.
So how does all this relate?
If your primer has a soft cup it will flow before a harder one.
The CCI 250 magnum rifle primers I have used on Heavily loaded J words for long range ammo show no signs of flowing or overpressure yet they are running at about 61,500 PSI according to multiple sources.
I have heard a number of actual industry professionals state that primers are not a good indicator of pressure and my experience has shown me why. The hot pistol loads with Fed. primers that were easily pierced were just fine with other primers.

This test has been both comforting and somewhat disturbing.
Comforting in knowing the Mauser won't likely blow up for small infraction, but disturbing in that it won't start giving easily noted signs until things are way bad.

YMMV!
Best regards!

[fouronesix]

QL pressures and primers.

This teat has been both comforting and somewhat disturbing.
Comforting in knowing the Mauser won't likely blow up for small infraction, but disturbing in that it won't start giving easily noted signs until things are way bad.

YMMV!
Best regards!

Seems that way to me also. With these older type actions that are Mauser in design and from forged stock that has not been over heat treated so as to become brittle- they tend to huff and puff and yield a little at a time where usually the case head or primer lets go before the action lets go. Then from a safety or practical perspective, the gas control design becomes most important.

As to the primer flattening? I've noticed almost without exception, that factory loaded ammo from all the major companies when fired in factory built new magnum rifles will show some primer flattening. I do not believe they are exceeding the SAAMI limits of around 65Kpsi.

couple of examples

[john hayslip]

Seems like I remember once I read about someone who fired a 45acp in an 06 and the action held without difficulty but the bullet came out quite a bit lengthened (Hatcher's Notebook maybe???).

[copperlake]

QL pressures and primers.

Some fellow reliable and honest shooters from the flatland (ILL.) did a test with small rifle primers and found Rem. primers to be much less susceptible to this type of problem leading us to believe the have much harder cups.

DCM, and it's interesting that this test used REM primers and brass. The last batch of rounds loaded for the stress test (49 gr.3031) have a few with CCI LR primers. I full length re-sized some of the cases from the very first test using the 170 gr. bullets. I do not plan on re-using brass for these maximum loads going forward but only have so many. With four actions, I'm going to need more. It would be great to have some different brands, which I will try to do.

Thanks for the better explanation of Quick Load, and again, for the help.

[copperlake]

The latest

I fired five rounds of 49 gr. 3031, 2 REM. primers 3 CCI large rifle, the CCI cases resized full length. Same results: easy extraction, no pierced primers. The only notable thing is one head expanded by .005", the rest were normal and the felt pen markings disappeared on one. A walk in the park. Discolorations were on the brass already. Close examination of the action and parts shows nothing obvious. I'm kicking myself for not measuring the receiver diameter before testing but it now shows 1.304" at the widest.



I'm going to stop with this action and mount a '93 in the torture chamber. This particular action has had, in places, as much as .036" in diameter removed from the receiver ring and probably everywhere else. It is nicely blued but way overworked. The lug buttresses's are very hard, much harder than the Swede. Fortunately, the same bolt fits this action. I'm going to fire five of the same loads plus the 51.5 gr. that blew the primer last time.

[DCM]

Thanks for the better explanation of Quick Load, and again, for the help.

You are quite welcome!
My part was much easier than yours, I actually wish I could be of more help and I am more than willing to help in the future too!

This is an area of great interest to me after witnessing a rifle come apart directly in front of me years ago.
A different rifle under very different circumstances and thankfully no one was seriously hurt, but it got me thinkin.

[copperlake]

Well, so much for those weak Spanish actions. This '93 Spaniard behaved exactly like her bastard cousin; 6 maximo rounds that acted and look EXACTLY like the ones from Sweden. The only difference, and a small one, is the 'blue pill' round affected the bolt actuation more. I had to put the sled in a vice and use leverage to open the action. And no wonder as the head expanded to .490 at the widest. It molded more to the bolt face. Also, I believe the first 'blue pill' did not vaporize the primer and that it was mishandled by me. This time I looked in the action before rodding the case out and could see the primer. I was more careful and retrieved it. It no longer had a friction fit and easily fell out. It is pierced, crumpled and the face absolutely flat. One other thing to mention is that with these hottest loads the stamps on the cartridge head are weak from being mashed into the bolt face, they are but a little bit from setting loose and completely flowing. I just can't mash anymore propellant (3031) into those cases! If it was an improved chamber we could do it!

I have never believed that the Spaniards were 'weaker' than the Swedes. This is not proof of that but it does say something. Of course, the main course is yet to come so we shall see. I'm a betting man, though and I bet in the end, there isn't spit difference between the two. No smith that was worth the name would EVER take a Spanish mauser that had .035" ground off the receiver and make something of it. That's why it is ONLY a blow-up candidate. Now, having said all this, I suppose I should also put the original 48, 49, and 50 gr. rounds through it too in order to be same-o same-o.

So here we are, I'm going to unscrew the barrels and check for set back but no more. I need some more umph to blow them up, and I think, that says a hell of a lot. Frankly, I'm impressed.

[EDG]

If you have electric clippers, electric razor or other source of small amplitude vibration you might get another couple of grains of powder in those cases. Another trick would be to neck size only. The 3rd and last trick would waste your earlier data. That would be to try WW brass which will be a good bit thinner and lighter. It is sometimes a good bit harder so the load to failure might a lot different.
The maximum effort would be to combine all 3 techniques.

I do not have a good digital camera or I would share one of my adventures in case demolition.
I blew two primers with a starting level load in a M91 Mauser many years ago and kept the brass as proof of the goat roping. The bullet was the Hornady 174 grain RN and the powder was AA2495.
The brass was USGI S L 54 which is very well made and tough. I bought 1000 of them and have been forming them into 7.65 and 8X57 brass for decades since they have no caliber nomencalture. The two rounds that popped ironed the headstamp lettering almost flat. There was a tiny puff of smoke from the action but nothing else.

[fouronesix]

Well done!
Says a lot about the "old stories" of how the basic Mauser with the right steel is one tough action (albeit maybe "softer" than current standards). Yield a little, until the brass lets go. As opposed to some other actions that may be of more modern steel or harder or more brittle steel that will not show set back or expansion with increasing increments of overpressure ......... until either the brass goes or the steel fails/bursts or both.

[shredder]

shredder, I don't have any headspace gauges, I used the tape method. I know you can read all you want about how horrible that method is but in this situation, with the control I have, I believe it's as valid enough. When I put the components together I had to remove some off the barrel face and a little off the left locking lug to get the bolt to close with very slight resistance on three different batches of REM 8mm ammo. All of these loads I fired today chambered the same way, a little resistance. I Took a dental tool and ran it against the locking lug buttresses and cannot feel a ridge. We'll see, some more high end torture and I'll unscrew the barrel. Also, when you look at these fired cases one would say that it has a tight chamber; there is no undo bulging towards the head of the case. You look at them and say, "that looks perfect". The action had no set back when it started out.

I do wish I had more tools to make this a more fruitful effort. ANYONE OUT THERE WANT TO LOAN SOME HEADSPACE GAUGES ? I'll pay shipping.

From what you are describing it sounds like the headspace is likely unchanged or at least very slightly enlarged. If your rounds still chamber with a bit of feel, not much has changed. My headspace gauges are in 30/06 or I would send them to you! Keep up the good work.

An old gunsmith taught me to use a go gaugeto measure headspace. It starts with stripping the bolt and removing the estractor. He used a tiny dab of grease on the bolt face and stuck a little cutting of solder on there. Put the gauge in the chamber and close the bolt. When you open it up, retrieve the tiny piece of solder from the bolt face which will now be a little flat pancake and measure it. That thickness is the amount of headspace the rifle has over "go" measurement. It will give you a precise indication of any change or setback.
I am following your experiments with interest.

[copperlake]

END OF THIS RUN

Well, I put more rounds through the Spaniard to make the regimen exactly the same for both actions, I then unscrewed both barrels. No visible set back on either under the magnifier. My camera just doesn't do well with closeups when there is a disparity in dept with things to auto-focus on. I did remember to measure the diameter of the receiver and it did not change.

So, until I get some more powder, I'm going to stop. I could do the same with the other actions but I'd rather wait and be able to do a complete cycle from beginning to destruction. It's been a lot of fun and for me, some surprising results. I must say that I'm beginning to develop some theory's about the actions themselves and their derivative urban legends. Certainly these subjects, under the conditions as set out, behaved remarkably the same. It will be interesting to see which one fails first. I have a bet on the Swede, but I'm biased. Overall, I'm quite pleased with set up and what's been accomplished so far. Far and away the best part has been the conversation.

I did start another thread about a '95 Chilean that I'm thinking about intentionally making it so the primers are pierced. I would video the results and not do it in a cage. I'm wondering what would be the best substrate to catch whatever leaves the action, so to speak?

Stay tuned.

Regards and thanks to all,
Mark

[fouronesix]

For camera protection, I used a thick plexiglas shield in front of an already "hardened" special purpose camera.

As as far as small parts capture it depends on how massive they might be and at what velocity. I know materials like rigid foam or celotex are not good ballistic capture media. It could get expensive? I'd think something like a 3/4" plywood surround (quonset or igloo shaped) with a top layer of thin sandbags would capture most.

[EDG]

Styrofoam backed up by heavy corrogated paper backed up by plywood should catch and stop splinters.
You might be able to use a large beer cooler surrounded by a large carton surrounded by a plywood box or some similar confifuration.

[copperlake]

I've been captivated by thinking about what other things I can do with paperweight actions, I decided to do some variations on more of Ackley's explorations; that being bolt head pressure. I ground off the left locking lug and head support off a bolt I have that had some of the head support already broken off. I'm going to use the second of the Oviedo mausers I have dedicated to the tests, one that is very soft and has .004" set-back on the top lug recess. This action is entirely soft and can be easily filed anywhere. I will fire several rounds below the primer failure point of 51.5 gr. of 3031 say, 49 or 50 gr. Then, I will remove the other lug and build up the action in the same fashion as a '95 Chilean with the third safety lug behind the bolt. After that test I'll remove the lug; it will be without anything to prevent rearward motion of the bolt. I'll have to figure out a way to fire it other than the drop hammer as the bolt flying back would probably destroy it. I'm thinking a block of wet potters clay to perform the function of a human head to 'catch' the bolt, so to speak.

Headspaced the same as the previous tests.

[copperlake]

Well, I intended to wrap up the first phase tonight but my backstop blew apart so I'll find some lumber tomorrow to continue. It appears that the 'hot' loads made it 12" into the timber from point blank. Some hung together, some not. An interesting one is at the bottom of the pic. The boattail bulged and for all the world looks like the front end of a FMJ.

First, I fired one of the factory REM. 170 gr. just to test - no problems. To conserve brass and because I don't care what happens in this test, I full length sized that first round and two that were fired previously with 49 gr. 3031, then reloaded them with the 220 gr Sierra boattail and 49 gr. 3031. I noticed that pushing the primers into the second cases was too easy. The first round fired was the reloaded first round; nothing untoward except two vertical splits in the case shoulder. The second round did not fire and the third round blew apart the backstop. No hard extraction, nothing that would alarm anyone but the heads of the twice-fired cases are looking a little tired, as in smushed. They are expanding. The bolt looks exactly like it did to start.

Tomorrow I'm going to go all the way with a 51.5 gr. primer destruction load. If nothing happens I will forevermore smile when I read about those Spanish mausers and how dangerous they are. Hell, I'm already there!

[copperlake]

Well, I found a log that wasn't covered with snow out back and brought it in to the shop. I fired two more rounds of 49 gr with nothing unusual to report, these and subsequent were once-fired with either 48 or 49 gr. 3031. This was getting to be boring so I loaded 51 gr. and got a nice pierced primer for the effort. I noticed that the powder was not filling the case as full as with virgin brass, which makes sense considering the customization they were experiencing. As a matter of fact, one firing @ 49 gr. stretched the cases .010-.012". Getting kind of tired of repeating myself, I crammed 52.5 gr. into a once-fired case. I will leave it to our friend, DCM, to tell us what that pressure is. The result was exciting! Finally! The report was considerably louder and mysteriously, I watched from the door to my bunker a fluorescent bulb over the bench at the back of the shop suddenly shatter. Walking there first, I couldn't see the reason for it. Pulling the action from the torture chamber I didn't see anything unusual until I tried to open it - it was frozen solid. Cool! I put the sled in a vise and realized I'd break the bolt handle if I went for it, so I unscrewed the barrel and this is what was revealed:



Other pieces of brass fell out during autopsy and there was a good deal of black residue at the business end of things. I determined that the light bulb shattering was caused by brass exiting the rear of the torture chamber. Even after I removed the piece of brass that was doing it's best to go out the vent hole, I couldn't open the action. Further examination revealed that the set-back was so much that I had to knock the bolt forward to release it. I must say that I thought for sure that this one-legged '93 spanish mauser would give up the ghost. NOT! When I cleared everything the action opened like it was new. And here is what I found:



The set-back measured .085". As you can see, the impression of the bolt lug is like it's been pushed into bubblegum. The receiver ring did not grow in diameter. After all of these extreme rounds, from the beginning, all the other bolt parts show absolutely no outward signs of abuse. Here is a picture of the brass. The separation occurred right where the case did not expand fully against the chamber. The edge is extremely sharp. I used a 1/8" pipe tap to remove it from the chamber and unfortunately, had to pinch the neck in a vise to remove it. The primer, that has some head material attached to it, is flattened to .025".



All in all quit remarkable. Being a betting man, I would have bet heavily against this outcome. It makes me wonder about all the stories about actions coming undone. I've got to get something to eat but there is more to come. I did remove the remaining lug and did build a 'fake' '95 mauser.........Stay tuned.

[nhrifle]

If you are up for some more testing after these actions have expired, might be kind neat to repeat the tests on a low numbered 1903 Springfield. It would, of course, be preferable to find one that Bubba had his way with and no longer had any collector value. I have such a specimen here that I use only for light loads with cast boolits. Many moons ago someone cut down an original C stock rifle into their rendition of a sporter, and I still cringe when I think what that stock in original condition is worth today. The chamber is very generous (bolt drops on the no-go gauge as if the gauge wasn't even there) and it is in the 200,000 serial # range, and I'm pretty sure it was built sometime around 1917.