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Thread: RRB #5 7MM Spanish Mauser

  1. #1
    Boolit Mold
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    RRB #5 7MM Spanish Mauser

    Hello Hopefully in the right spot! Looking for advise and info for Ammo for a #5 RRB 7mm Spanish Mauser carbine. The barrel is marked 7mm S.M. Reloading etc...

  2. #2
    Boolit Master
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    Kinda Greek???
    A picture may be better... But...Bets are it is a good ole Spanish Small Ring Mauser in 7X57... You however seem to need a Gunsmith..

  3. #3
    Boolit Master MarkP's Avatar
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    I have a Remington Roller Block like yours....... The first time I fired it a got a face full of gas. First loading was very low pressure and the case mouth did not seal resulting in gas coming thru the firing pin hole.

    I use a FL die and only size about half of the neck; just a slight body size and leave the should neck junction alone. I index my cases when I chamber them (headstamp text at 12 O'clock) I shoot the Mid South Shooters Supply LEE Soupcan unisized in mine 0.289" ish. They are in a custom mold section on their website. I finger lube with LARS BAC -- and run thru a push thru die to shave off excess lube but not size the bullet.

    It will key hole 30% of the shots if I shoot 0.285" thru it.

    My bore is dark but still shoots okay. It took hundreds of wet brush strokes over a course of a week or two to get clean patches coming out after I purchased it.

  4. #4
    Boolit Master
    405grain's Avatar
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    Generally, cast bullet 7x57 loads in a Remington rolling block should be well within it's safe level for pressure. Published jacketed loads usually have the lowest listed loads as the maximum load for small rings and rolling blocks, but I'd advise starting below those "maximum" loads. To get you started, you can download a copy of the 3rd edition of the Lyman Cast Bullet Handbook here: https://marvinstuart.com/firearm/Man...-%20Reduce.pdf

    The forth edition Cast Bullet Handbook is for sale from many sources, and has much more information. Also, as a general rule, the 7x57 Mauser cartridge generally likes longer, heavier bullets best. I've had good success shooting cast bullets of around +/- 170 grains. I've been getting PPU brass in 7x57 from Graf & Sons, and have found good loading information in this caliber easy to come by. A word of warning about rolling blocks: The moment that you close the breech on a loaded round the rifle is ready to fire. As you lower the hammer into the half cock position be especially careful of the direction that your rifle is pointing. The only safety on a rolling block is the one between your ears.

  5. #5
    Boolit Master

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    I've been shooting and reloading the 7mm Spanish Mauser (often incorrectly known as the 7X57) for my M1902 rolling block carbine and rifle lately. I'll share a few observations on loading for these guns. Anyone familiar with these 7mm military rifles is probably aware that they often have loose chambers and excess headspace. George Layman, probably the most knowledgeable guy in world on military rolling blocks, in his Remington Rolling Block Military Rifles of the World book, does NOT recommend shooting them. He also states that the ammunition was never intended to be reloaded. George and I have discussed this offline quite a bit and I fully understand where he is coming from. This does not mean it cannot be done, but it takes special care.

    My observations:
    1. I do not recommend shooting any factory ammunition due to potential headspace issues. If that is all you have, break it down. Then expand the neck with a .30-06 expander. Then start sizing the neck down until the breech block will just barely close fully - then stop and lock your sizing die in this exact position. Anneal the case neck. Only size the neck with this die from now on. This should set the proper headspace. Then reload with a mild charge.

    2. When fired the case necks will grow in diameter a lot due to the loose chambers - .015" - .017" - that is a LOT of expansion. Neck sizing back down will work harden the brass a lot. Its a good idea to anneal frequently. The cases will also stretch and grow in length. Check and trim as necessary. Brass that gets too long won't chamber all the way.

    3. With all this working of the brass, even with annealing, brass life may be limited. Keep your loads mild. This will contribute to longer brass life.

    4. This rimless cartridge does not work well at all with the rolling block's extractor. It is VERY easy to slip the rim past the extractor, because the rim does not stick out past the case body. Bring a rod with you to the range to knock out cases - I know from experience....

    5. This is not a rifle for a beginning or casual reloader. It takes extra care, extra work and vigilance to reload and shoot it safely. But when done properly, it is a fun and very rewarding rifle to shoot.

    Here is a video I made shooting my carbine.
    https://youtu.be/EDsCb-CvBWM
    Last edited by ndnchf; 03-20-2023 at 12:32 PM.

  6. #6
    Boolit Master brstevns's Avatar
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    one other thing to try is take brass and expand the neck up to 30-32 cal, then put it in your 7m/m die sizing back just a little of the neck at a time. Trying the brass in you rifles chamber as you go. Keep this up until the action will close but not close real easy.
    If your bore is .288 or larger try to find a bullet mould that makes a bullet of at least that diameter. Shoot as cast if necessary,
    Make up a few dummy rounds with the brass you formed and adjust the bullet depth till aition will close . You should not lose any brass do to having a long chamber. Once fired neck size only.
    Worked for me with a RB that had a .290 bore with no key holing. You might also try paper patching your bullets
    I found a lyman 287308 mold that worked great.

  7. #7
    Boolit Master

    pworley1's Avatar
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    Quote Originally Posted by ndnchf View Post
    I've been shooting and reloading the 7mm Spanish Mauser (often incorrectly known as the 7X57) for my M1902 rolling block carbine and rifle lately. I'll share a few observations on loading for these guns. Anyone familiar with these 7mm military rifles is probably aware that they often have loose chambers and excess headspace. George Layman, probably the most knowledgeable guy in world on military rolling blocks, in his Remington Rolling Block Military Rifles of the World book, does NOT recommend shooting them. He also states that the ammunition was never intended to be reloaded. George and I have discussed this offline quite a bit and I fully understand where he is coming from. This does not mean it cannot be done, but it takes special care.

    My observations:
    1. I do not recommend shooting any factory ammunition due to potential headspace issues. If that is all you have, break it down. Then expand the neck with a .30-06 expander. Then start sizing the neck down until the breech block will just barely close fully - then stop and lock your sizing die in this exact position. Anneal the case neck. Only size the neck with this die from now on. This should set the proper headspace. Then reload with a mild charge.

    2. When fired the case necks will grow in diameter a lot due to the loose chambers - .015" - .017" - that is a LOT of expansion. Neck sizing back down will work harden the brass a lot. Its a good idea to anneal frequently. The cases will also stretch and grow in length. Check and trim as necessary. Brass that gets too long won't chamber all the way.

    3. With all this working of the brass, even with annealing, brass life may be limited. Keep your loads mild. This will contribute to longer brass life.

    4. This rimless cartridge does not work well at all with the rolling block's extractor. It is VERY easy to slip the rim past the extractor, because the rim does not stick out past the case body. Bring a rod with you to the range to knock out cases - I know from experience....

    5. This is not a rifle for a beginning or casual reloader. It takes extra care, extra work and vigilance to reload and shoot it safely. But when done properly, it is a fun and very rewarding rifle to shoot.

    Here is a video I made shooting my carbine.
    https://youtu.be/EDsCb-CvBWM
    This is good advice. I do basically the same thing except I use paper patched bullets to get up to the right diameter to fit my bore. Shooting them is worth the work.
    NRA Benefactor Member NRA Golden Eagle

  8. #8
    Boolit Buddy kootne's Avatar
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    I have a clip full and a couple extra amongst the mementos of my great grandpa's service with the 3rd Wis. Volunteers in Porto Rico. He was in a skirmish or 2 and I assume he picked that ammo up as trophy of the event. The cartridges, head stamped 1896, are longer from base to shoulder by a small but obvious amount when laid alongside current 7x57 shells. There was a warning to this effect published in the American Rifleman about 60 years ago. As I recall, Remington said the rifles they checked at that time were OK to the gauges left over from original production but all would accept NO Gauges of SAAMI spec. I believe it was also mentioned the current 7x57 dimensions were not adopted as standard til the 1920's. Remington's conclusion was hang them on the wall and get a newer gun (ha-ha, like we are going to do that). So the practices mentioned above to get the 7x57 brass to fit the chamber seem prudent and should be heeded.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check