Murata headspace problems. What do?

[Depreacher]

Yes, my friends, the ol' preacher has out Exotic-ed (spelling/grammer?) many of you here. My new assault rifle is an 1889 Japanese Murata 8X53R bolt action repeater. The brass from Buffalo Arms was $3.20 EACH! I noticed that it had 45-70 gov't on the case head so maybe I can eventually form my own. The bolt closed on the case easily (too easily). I had to add .012 of paper shims to get the bolt to have resistance halfway down. Figuring the crush factor on paper, i think I have about .008 to .010 headspace clearance. This being a rimmed cartridge, how much can I get away with?
The bolt head is separate, so There is a place to put a thin round shim washer to DECREASE the headspace problem. The firing pin appears to protrude enough (from many years of use, and snapping) that I will still have plenty of protrusion left. In my many years of small engine and Honda atv repair I remember seeing many such thin spring washers, but sold out 4 years ago. Any ideas on how to find such? Ebay maybe?? Maybe just buy spring shim stock and carefully trim out one. SAFETY is an issue here, of course. The bolt has a rear locking lug, plus the massive bolt handle locks tight against the equally massive right receiver bridge (split bridge). The machining, and what there is of the original blue is excellent. Equal to any Mauser military rifle I've ever examined. I am impressed with the workmanship, and many asiatic innovations. I may have 4 fleeing shooters on each side of me at the range, but I am still determined to shoot it. What do you think about the shim idea??? I have owned and shot rifles 25 years older than this with 4759 (50-70 1863 Sharps conversion), and still have both eyes. THANKS for any help. Preacher ps. Yes, it will go through the tire test first with a slight overload.

[jhrosier]

Preacher,
I have shot bottlenecked cases with thin rims using another method.
I wrapped the case head forward of the rim with narrow making tape until it was a tight fit in the chamber for the first shot. The shoulder will expand to fit the chamber and you will not need to do this again. Since I was shooting a low pressure load (less than 30Kpsi), I also used large pistol magnum primers to eliminate primer setback. You can get the masking tape in narrow widths where quilting supplies are sold.

Jack

[Ricochet]

If you can seat a bullet out to touch the rifling it will accomplish the same thing. (Except the tape also helps to center the case in the chamber as it expands.)

[Depreacher]

Now why didn't I thunk of that??????????? THANKS guys, Preacher ps. I'll also remember the Large pistol mag primer trick. Will also probably take the flash hole out to .099.

[Pavogrande]

Preacher - not going to comment on whether shimming bolt head is ok or not, but if I shimmed it I would use regular stainless shim stock.
Another way - Make three dimples in the case rim effectively setting case back. I have also seen very thin copper wire wound around base right in front of the rim, but don't know if that was successful or not.

Donnelly says, " Make cases from .450 NE - Bell - cut to 2.4" and anneal, build rim up to .09 thick (but not how to do this) f/l size and trim"

With a head diameter of .542 it seems 45/70 can be squeezed down but at an overall length of 2.105 is shorter than 11mm Murata which is 2.36" - my two cents

[nicholst55]

Having .008-.010" of "clearance" between the case rim and bolt face is not uncommon on Lee Enfield rifles, for one. It isn't necessarily a good thing, but...

One solution for the LE is to remove the bolt head and soft solder a piece of shim stock of appropriate thickness to the face, and then trim it to fit. Then you need to drill a firing pin hole through it, of course. I don't know if that procedure might work with your rifle, or not. It might be worth considering, though.

[Depreacher]

Pavogrande,

THANKS for the reply. This is the 8X53R case I need to form. Frank Barnes states the length to be 2.06. The cases that Bufallo Arms sent are 2.058 (good enough!), made from 45-70 brass. My spare 45-70 cases caliper out at 2.09 so I am good to go if I can figure how to reduce the neck to accept the lee .329-330 boolit. I can get 8X53R FLdie sets from Bufallo arms for $107.00, but will need to neck down in stages. Maybe a .416 Rem lee die with some of the bottom cut off (I've done it before), and a lee .348 win die, then the 8mm Murata FL die. Maybe????? A year and $1000.00 later I will be the resident expert on reloading for the 8X53R. What an honor to have bestowed on a poor humble soul.
I am not familiar with the Donnely info you provided. Does he provide any loading data for the 8mm Murata???? I DO APPRECIATE the help!!! Preacher

[Depreacher]

THANKS nicholst55,

Good idea on soldering the shim to the bolt. Unsoldered, it might shift,with the guide groove I cut in it jamming up the bolt. With my luck, it could happen. THANKS AGAIN, Preacher

[KCSO]

That is within spec for a miilitary rifle. That is about the same headspace as mine had and I had no problems with the gun.

[Pavogrande]

Preacher - It is tough to get old and stupid - I read your post twice and still converted 8mm to 11mm - I am fussing with a couple 11mm now so thats my excuse and I am sticking to it!

Donnelly says: "8mm x 53R Muata - Make from 7.62 x 54R russian, turn rim to .538 dia and back chamfer. Taper expand to.335dia and cut case to 2.1". F/L size in 8x53r die, trim to length and fire form."
He gives the folowing load: 250g RN .329dia, 47.4g IMR4320, source JJD (donnelly)
I can provide all the case dimensions he gives if you need -
Sorry for the confusion -

[Bigjohn]

Preacher; If your headspace issue is not caused by wear and tear (use) on the rifle, then I would see no need to propose a fix such as soldering a shim of steel to the front of the bolt face or any other place.

In reading the above thread I have seen several solutions to the problem offered; 1) such as seating the Boolits out to contact the rifling so the case is hard up against the boltface for the first firing only. This process may require a heavier than normal boolit. 2) Peening the case rim to form a thicker rim and again hold the case back against the bolt face for fireforming of the cases. This process could lead to damaged cases if you misdirect a hammer blow.

My assessment of the problem is; the cases need to be fireformed to better fit the chamber and remove the headspace. Both of the above mentioned methods would achieve this and subsquent firings would not have this problem.

I have knowledge of and used successfully, one other method which I will describe.

Step 1: Expand the case necks to a larger calibre (say 9mm). Anneal the case necks if you believe they need it, prior to commencing this process.

Step 2: Partually resize the necks in the sizing die until you can close the bolt on the rifle with the required resistance on the bolt handle.

This process is designed to leave a small shoulder in front of the original shoulder which will bear on the shoulder neck junction in the chamber setting the case back against the boltface.

Step 3: Load and fire the cases. Normal loads will do.

If the brass is too hard from being 'worked', this could lead to some split necks. Hence my suggestion to anneal the necks before you start. I wish you success with whatever method you choose to use as all of then will achieve the desired results.

Unfortunately, due to the rarity of the rifles and ammunition I can offer you no further information about your rifle. I hope you can get it to shoot as you would like and any information you discover will help others with simular rifles.

Best of luck,

John.

[Depreacher]

KCSO, thanks for the advice. Did you own a similar rifle? Murata, Chassepot? Kopratschek??? I wondered if I was the only castboolit Murata type 22 owner. Preacher.


Pavogrande, This is the exact type of case forming info I need. I am ordering a box of 7X54R Russian/Norma brass, and a Lee .329 mould from Midway tonight. Norma always had extra heavy brass, so that's a little extra safety factor for peace of mind. I believe I'll opt out on the 47 gr. charge of 4320 Donnely recommends, staying on the 20-23 gr charge of 4759 that Barnes gives. 1600+/- fps is plenty good to drill paper targets, or a Whitetail. This baby has a 29.5" bbl, so 1600-1700 with a 205 gr. won't be hard to achieve. BTW, the bbl looks straight, super straight!!!!!!!

Bigjohn, your advice coupled with what Pavogrande gave sounds best to me. I will do the secondary shoulder thing giving me zero clearance on the headspace. Even if I have .008 to .010 of the case base "hanging out of the chamber", the heavy Norma brass will withstand the loads I shoot. Actually, The Murata may support the case head as well or better than my 03A3, and I'm sure not scared of 45-50,000 c.u.p. loads in the 03A3. of course the steel in the latter is better. The Murata has 1889 steel, but then, the Japanese were always masters at heat treating, gulp, I hope. Preacher ps. Many THANKS to you also

[jhrosier]

Preacher,
If you haven't already made your purchase, check out Lee's closeouts page.
I got mine there for cheap.

Jack

[Depreacher]

Dear Members,

I DO appreciate the advice everyone gave. I found out why Buffalo arms uses a 45-70 case instead of a 7.62 Rusky. Remember, my rifle has .008-.010 headspace with Buffalo arms brass they make from a Rem 45-70 case. The Rem 45-70 case rim is .064-.066 thick, while the Norma 7.62X54R is only .060-.061. Even if I fireform using the secondary shoulder method, .013 to .015 of case head hanging out of that ancient chamber is just too much for me. Now I've got to figure out how to reduce 45-70 brass down to accept a .329 boolit, reducing a little bit at a time. My brass is circa 1980 (shot 10 to 15 times), so, it's time to neck anneal. Maybe just biting the boolit (sorry!) and buying 17 more cases at $3.20 for a grand total of 20 cases would be best. If neck sizing only, it would take a long time to wear them out. Preacher

[Pavogrande]

Preacher -
At that price I would try dinging the rims - Would not take much tooling to do it --

Fire forming to fit the chamber would theoretically only leave a max of .013 unsupported, maybe not even that much. Any modern brass would be strongest at that point.

my two cents