Mauser 93
Some time back I acquired a sportsterized model 93 Argentine Mauser. After some investigation and research It was figured out that it was a 7 x 57. I slugged the barrel at .282 but the slug showed no signs of rifling even though it seemed well defined in the barrel. I acquired some dies and brass and loaded some starting loads with 150 gr win PP over 34 gr and 34.5 gr. of H4895. The first two rounds were fired remotely for safety reasons. Subsequent shots wer fired at a target with a 3" bull at 25 yards. The first couple rounds hit the bull but keyholed. I then fired a couple of the 34.5 gr loads with the same results. I did notice the the necks on the brass were carboned and expanded more than I expected (about .12 more than the unfired round)otherwise the rest of the case was within spec. Seems like this gun might have a generous chamber. Just to make sure I hadn't made a mistake and it might be 8 mm, I seated a 30 cal bullet in one of the fired cases and tried to chamber it but it wouldn't chamber.
Now for a couple questions. The gun has a ring (for lack of a better term) on the end of the barrel. The hole/bore is oversized in that part of the barrel. Is that normal for these guns? I know keyholing is often a sign of lack of stabilization. I don't know the twist of this barrel. I am questioning:
1) if the barrel is shot out, though the rifling seems fairly well defined
2) if the load is too slow, though according to research pressures should be kept to around 47,000 CUP which according to the book would max me out as 36 gr of H4895 but not gain me that much speed.
3) if the bullet is heavy enough. My understanding is that these were originaly loaded with a 178(?) gr bullet.
Any insight?
Now for a couple questions. The gun has a ring (for lack of a better term) on the end of the barrel. The hole/bore is oversized in that part of the barrel. Is that normal for these guns? I know keyholing is often a sign of lack of stabilization. I don't know the twist of this barrel. I am questioning:
1) if the barrel is shot out, though the rifling seems fairly well defined
2) if the load is too slow, though according to research pressures should be kept to around 47,000 CUP which according to the book would max me out as 36 gr of H4895 but not gain me that much speed.
3) if the bullet is heavy enough. My understanding is that these were originaly loaded with a 178(?) gr bullet.
Any insight?
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My WAG is that either it's been rechambered for a different cartridge, or in actual fact that it's a 7.65 Mauser which was the Argentine military rifle cartridge, not the 7mm.
The only way you will be able to find out, is to have a chamber cast done. Your just wasting your time now, as it appears that you are firing bullets that are way undersized for the bore.0 -
Something isn't right here.
First off, there is no such thing as a model 93 Argentine Mauser. There is a model 91 and a model 09. Both are originally chambered in 7.65X53 but if that were the case, the bore would slug around .313".
There was a model 93 Spanish Mauser, possibly what you have. These were chambered in 7X57.
The ring you are seeing could be a counterbore to clean up some of the slop at the end of the barrel. Fairly common for milsurp guns where overzealous troops cleaned too hard with steel rods and no guides.
Now to keyholing. I would be very surprised if the bore really is .282. .284 is spec but most of these have rather oversized bores. Mine measures .288" across the grooves and .280 across the lands. What does the .282 measure? If it is across the lands (the raised portions of the rifling) then you are only getting 1/1000" of grip on the bullet per side- possibly not enough to stabilize it. It's the groove measurement that interests me. In which case the answer is a fatter bullet- hard to find unless you cast your own- though a light charge of fast burning powder or ballistic filler would help. If you have access to IMR SR 4759 try about 18-20 grains of it. If across the grooves, then we'll have to look elsewhere for the culprit.
They were originally loaded with a long round nose bullet but while this might help some if it won't stabilize a 150 grainer at all it won't stabilize the heavier one, odds are. Hornady makes a 175 gr RN that works pretty well.0 -
I also considered the possibility of the 7.65 (.311). That is one of the reasons I seated a .308 bullet to see if that combo would chamber. My thought was that the case dimentions were "close enough" between the 2 that if the .308 bullet would chamber that is probably what I had. The case with the .308 bullet(seated to minimum OAL) wasn't even close to chambering and the barrel left a distinctive ring high on the bullet ogive where it made contact. Considering, when slugging the barrel I started with a bullet sinker of more than .30 and it came back out at .282 the 7.65 doesn't make any sense either. Other than the neck the case appeared to fireform to within spec dimensions for the 7 x 57.
Looks like I'll have to order some cerosafe for a chamber cast.
Jonk.....I appreciate any and all input. I know little about these guns. Even some of the stuff I found on the net seems to be contradictory at times. This is why I am asking questions
quote:First off, there is no such thing as a model 93 Argentine Mauser. Good to know. I was under the impression Argentine/Spanish mausers were pretty much the same beast. Apparently not.
I'll have to try slug the bore again. The first slug I drove through did not pick up the rifling for some reason. The rifling is there, I can distinctly see i in the bore but it did not show on the slug which was easily over bore size before I drove it through. I have a feeling the slug may have gripped the rod I used to drive it through (I'll use a larger diameter next time) and went straight through "stripping" the rifling off the slug thereby giving me only the land measurement.
I am also now wondering if some cleaning rod abuse has not enlarged the muzzle end of the barrel. I may have to drive a slug in part way into the muzzle then measure it. It's possible the .282 could be from the smallest part of the bore near the throat. If this is the case the bullet being undersized near the muzzle might cause it to lose stability.0 -
The early Argentine Mausers, ( model 1891 ), are easy to identify because they have a external magazine that hangs down in front of the trigger guard. The Spanish Mausers even though they were made just a couple years later, have a internal magazine that is covered entirely by the stock.
Here is a photo of a Model 1891 Argentine Mauser, showing the external magazine.
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quote:They were originally loaded with a long round nose bullet but while this might help some if it won't stabilize a 150 grainer at all it won't stabilize the heavier one, odds are. Hornady makes a 175 gr RN that works pretty well.
Jonk, while the most common military load was the 175grn RN, other South American countries used loads as light as 139grn. Mexico used two different loads, a 155grn and I think a 162grn.
The standard military twist rate was 1-9 for Spain, and I believe they used the 175grn load exclusively. I haven't found any data supporting what twist rate countries like Brazil, Mexico, Uruguay, and Colombia used.
Commercial barrels have used 1-8,9, and 10.0 -
dakotashooter2,
I combined a couple of your posts to save on responses since we limit them to 10 per thread. If by chance this gets locked at 10 or so posts simply start another thread by adding something like 'Part 2' to the title. Then we can continue the dialogue.
I have two questions:
- Did you scrub the barrel thoroughly before you started this process of slugging?
Some of these old war horses need to something beyond a little attention to the crud that has been allowed to build up over the decades. It's possible you need a brush combined with an aggressive cleaner.
What does this mean?
"...and expanded more than I expected (about .12 more than the unfired round)..."
That number you wrote is a tad on the large side and it should have swallowed a cartridge with a .30 caliber bullet seated.
Best.0 -
Looks like it is the Spanish Mauser. I ran another slug through and while I still didn't get a defined rifling on the bullet there were definate high and low spots which measured .282 (same as before) and .288. I only ran this slug about 4" into the muzzle. I'm gonna run one more series of test loads with H 4350. It shows more velocity with less pressure than the 4895. I have my doubts it will change anything as far as stabilizing the bullet but my intent was to go with cast in this gun anyway. I just haven't gotten my hands on a mold yet. The neck expansion still puzzles me but it might just be the case of a loose chamber which might raise some heck with case life.
Something I forgot to mention is that on the fired rounds it did back the primers out a bit but there was no flatening whatsoever and the primer hits were the deepest I've ever seen. At least 2/3 the depth of the primer.0 -
"The neck expansion still puzzles me but it might just be the case of a loose chamber".........this is VERY common with the spanish rifle in general. 0
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