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Title: Designing a throat-fitted bullet for Paul Mauser's military standard M93 7x57 long guns 


We are talking about the Paul Mauser standard M93/M95 7x56 military surplus long rifles.I am currently doing an "assumption check" on the throat consistency of the M93/M95 small ring 7x57 Mauser guns based on the fact the only militaries that ever used them were Spanish, Mexican and South American (Brazil & others) all of which either had them made in Germany (Obendorf) or made them locally in Spanish or Mexican armories under direct Mauser license (german on-site inspectors, tooling and gaging either provided or always built EXACTLY to Paul Mauser's design which is the only way Mauser would do liscensing of a Mauser rifle before WWII).This is the question before the group -- is ANYONE aware of ANY M93/M95 Mauser 7x57 military built guns that DID NOT adhere to Paul Mauser's standard military throat specification? Is anyone aware of any M98 or M93/M95 7x57 guns built that used a different throat construction?Has anyone even got a M98 large ring 7x57 rifle in their gun safe? I don't think all that many M98's were ever made as the M93/m95 actions and the 7x57 were kinda "built for each other" ....=============================================================If any of you guys want to participate in a throat-fitted slug design for the M93/M95 Mauser rifles, here is your chance to say so. I have a catalog house that is willing to list a properly proven-out design, but to get there we need at least a couple of interested players who are willing to slug their throats and participate actively in the design process.Oldfeller==========================(edited 11/7/04 to add in M92-95 designations. I own a M93 Mexican/Spanish-built rifle for example. DeHaas in his Bolt Action Rifles lists the M92, M93, and M95 variants in 7x57 but I may just start calling them small ring mausers for convenence as the consistency of the chamber/throat is where we are focusing)

Oldfeller posted on 11/06/2004 04:58:06

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Reply to : Oldfeller


We are talking about the Paul Mauser standard M93/M95 7x56 military surplus long rifles.I am currently doing an "assumption check" on the throat consistency of the M93/M95 small ring 7x57 Mauser guns based on the fact the only militaries that ever used them were Spanish, Mexican and South American (Brazil & others) all of which either had them made in Germany (Obendorf) or made them locally in Spanish or Mexican armories under direct Mauser license (german on-site inspectors, tooling and gaging either provided or always built EXACTLY to Paul Mauser's design which is the only way Mauser would do liscensing of a Mauser rifle before WWII).This is the question before the group -- is ANYONE aware of ANY M93/M95 Mauser 7x57 military built guns that DID NOT adhere to Paul Mauser's standard military throat specification? Is anyone aware of any M98 or M93/M95 7x57 guns buil

 

Oldfeller,  Finally got my Cerrosafe slug poured today.  It took the goldangest contraption I have ever put together and the assistance of my wife, but the job is done.  E-mail or PM me your snail, please.  curmudgeon



NVcurmudgeon posted on 11/20/2004 07:24:16

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...........Awright, I poured one in my sexy looking but worn barreled 1895 Chilean.

All dimensions are to the closest foot, ........er thousandth

Chamber neck dia: .325"
Throat length...: .420"
Throat Dia .....: .292" (At casemouth)
Throat Dia .....: .287" (At beginning of lands)
Lands ..........: .280" (At 1" from casemouth)
Groove .........: .287" (At 1" from casemouth)

Muzzle, lands checked with pin gages that are -.0002"-.0000"

.277" nice slip fit. .278" goes in about 0.500" but will wiggle a bit so we have some cleaning rod wear to make it a bit oval.

I did this rifle first as it was the easiest to get to. I figured getting about an inch of the barrel from the casemouth should cover the bases of interest. Yup, this puppy is just a wee bit worn. Thank God for Loverins as it WILL shoot them to about 1600 fps. Don't even THINK about a bore rider

11-22-04 Update: My M98/08 Brazilian:

{comparison with the 1895}

Chamber neck Dia: .325 {0}

Throat Length......: .270" (-.150"}

Throat Dia...........: .288" ( At Casemouth) {-.004"}

Throat Dia...........: .287" (At beginning of lands){0}

Lands .................: .277" (At 1" from Casemouth){-.003"}

Groove................: .287" (at 1" from casemouth){0}

At the muzzle a .275" pin gage is a nice push fit. A .276" is a no-go. {-.002")

It's obvious the difference between the 2 is that the leade is worn forward a great deal in the 1895. Also the throat at the casemouth is eroded.

...........Buckshot



Buckshot2 posted on 11/21/2004 09:43:46

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Buckshot, sounds like yours might be even more worn than mine.  Measuring the across the rifling tops diameter (slug land bottom to slug land bottom) at .625" from your case mouth shift, what sort of number do you get?

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All the rest of your dimensions are in line with my worn slug more-so than the new gun guy's slugs.  And I dare say there are a lot more worn guns out there than virgin guns ..................

Is your rifling square-ish or have you got some of the "fired a lot" rounded top rifling?

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A thought, not a good one necessarily, but just one of those errant thoughts that comes when presented with some new data.

Buckshot, take a look at the sketch at the long tapered bore rider nose.  Now envision it covered with LEE microgrooves .... Naw,  too many microgrooves,  that might be too hard for the new bore guys to push their virgin rifling through, a whole crop of bore wall riding microgrooves.

Or, as a more practical alternative, envision  just a couple of 2-3 separate & lonely LEE microgrooves scattered up near the ogive end to give the bullet good full bore wall support at the front end.  I think you could cam load right on through 2-3 micro-bumps even if you had a tight virgin bore gun.

Or extend the ogive to the bore wall at .289" edge diameter then drop back down to the .280" new virgin gun not engraved at all number, similar to what we did with the K-31 slug and the pellet drawings.  This would give a substantial bore wall support to the end of the ogive that could be sized with the bullet bands to whatever your actual gun required.   The step would be .0045" tall that the rifling would have to engrave through, then the new bore guys would have rifling just laying across the tapered surface for additional loading support. 

Us worn bore guys would have a bore wall riding ogival nose band to tide us over until our bullet moved forward a bit on firing to find all the rifling, or we could just load it forward intentionally in the neck until we got some tapered band rifling land top marking too.  Our worn rounded rifling would punch through the ogival nose band pretty easily after all and we do have .100" of forward seating adjustability to go find a full seat on the rifling we do have.

Thoughts?

Oldfeller

 



Oldfeller posted on 11/21/2004 15:02:27

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The ogival nose band idea would look sorta like this (sticks up only .0045" tall per side). 

Remember, upon exit from the muzzle, the entire length of the bullet would be fully rifling engraved starting at the back edge of the ogive all the way back to the backside of the gas check.  From looking at muzzle data from Buckshot, the ogival bore wall band & the taper band is going to be crushed just about totally flat by the reducing barrel wall taper that exists in the older guns.

Counting the ogive tip bore wall engagement band, you would have over 90% of the bullet covered by both bore wall engagement & full depth rifling engagement, starting at initial loading & going all the way up the barrel to the muzzle exit. 

Downside to this excellent loading engagement,  IF you crush-load this sucker in place like a target guy you WILL debullet if you try to unload it.  Hunter guys won't want to load deep enough to get a full set of taper band engagement rilfing land marks, but may elect a somewhat lighter engagement to allow them to unload in the field.

Oldfeller



Oldfeller posted on 11/21/2004 15:34:18

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...........Oldfeller, "........ sounds like yours might be even more worn than mine. Measuring the across the rifling tops diameter (slug land bottom to slug land bottom) at .625" from your case mouth shift, what sort of number do you get?

I'm not following. You want a bore diameter at .625" from the casemouth? I have re-melted the chambercast material to pour the M98/08 (data posted in my previous post).

You can extrapolate a bit from the data. The throat is .420" long with a dia of .287" at the beginning of the lands (bore). Now, at 1" from the casemouth the lands are .280". So subtract that .420" throat length from the 1" length where the lands were measured and you get .580".

So over that .580" length the lands decrease in diameter from .287" to .280" or a .007" reduction. Someone with better math skills then I will have to extend that to the desired .625" length.

...........Buckshot




Buckshot2 posted on 11/22/2004 04:50:25

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If you assume the slope is a straight line the result is.2795.  My bore measured .280 at this point.

Ed 



E G posted on 11/22/2004 05:51:57

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Reply to : E G



If youassume the slopeisa straight line the resultis.2795. My bore measured .280 at this point.Ed





...........Thanks Ed. Nice to have folks around who can pick up the slack .

...........Buckshot

Buckshot2 posted on 11/22/2004 08:45:06

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<'m not following. You want a bore diameter at .625" from the casemouth? >


Buckshot, we keep trying to verify the critical fit up points on the bullet that would affect the bullet design. Rifling land top point to point (throat slug groove bottom to bottom) measured .625" out from the case mouth is the critical fit point at the end of the ogive of the bullet. The other one is the bore wall diameter at the point where the rifling starts.

Please pause and take the two measurements at the two critical design points shown on the bullet design before you melted your slug down to do the next one. At this stage of the game there really are only the two critical points, the end of the ogive (rifling engagement point upon loading) and the diameter start of the rifling (your lubricizing die size).

Oldfeller



Oldfeller posted on 11/22/2004 12:46:27

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.................Sorry, the throat-leade cast was re-melted after I got the measurements off it, bummer.

Ya know, it would seem at this point with the dimensions in hand (my M95 Chilean is more worn then your 1893 Spanish) that designing a cast slug to satisfy most the throat and leades, without de-bulleting issues is going to be tough.

What I see in looking at the measurements to this point ( I still have a couple to do) is that the throats are pretty consistant at wanting a .287" slug. I submitted one example with a throat to leade (begin lands) at .420" and another at .260".

The 1895 Chilean still comes in with it's worn leade as having lands within .001" of my Ex+ condition 1908 Brazilian. Obviously at different distances from the casemouth, due to the eroded forward leade. And you're not going to be able to match the .292" erosion in the throat at the casemouth. Right now, this rifle shoots well with the Lyman 150gr Loverin to about 1600 fps, and this is sized .285". You can forget a bore rider at almost ANY speed .

The point I'm trying to make is that like my worn 1895, the more body length to use is an advantage. Since the 1908 in MUCH better condition does well with the Lyman Loevrin also, I tend to believe that something along those lines would be the best compromise. And a compromise it will have to be. I think narrow drive bands and lube grooves at the nose is the way to go.

For one thing, it would ease engraving in a less worn rifle, and might also provide easier unloading without de-bulleting? It would provide a longer engraveable surface.  To be sure, there will be rifles out there like newer commercial 7x57's unable to use the design, but it's not aimed at those.

It would be a singular appearing design if not a full true Loverin. In other words you have say 4 bands on the rear of maybe .100" width and .050" wide lube grooves. The wide bands for twisting strength in the rifling and to add mass. Add in the GC shank and you have used about .700" of length. This portion would drop from the mould at .288". The balance of the bullet's length could be made up of narrower drive bands and LG's to a truncated cone nose with meplat.

The problem with the bore rider idea used in a design intended to fit worn rifles, is that if it won't actually ride (and missing it by .001" isn't riding) it won't shoot to potential. By trying to design on a solid nose or bore rider then it's going to be too big and too hard to force into the leade on some, and too small in diameter for others. The groups that it would fit and function like it's supposed to would be a third group.

Looking at the numbers reported so far, the diameters (throat, lands, grooves) are close to each other being a matter of thousanths of an inch. On the other hand, the LENGTH of the throats are being measured in tenths of an inch, and therein lies the major design problem.

...........................Buckshot



Buckshot2 posted on 11/26/2004 09:20:33

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Buckshot-

 It sounds like you want a modified 311407 scaled down to 7mm.



45 2_1 posted on 11/26/2004 15:17:25

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