Case forming question??

[JohnDY]

I am experimenting with forming 7.7 jap cases from once fired .30/06 Remington brass.  I have resized and trimmed twenty cases and every case now has a scratch the rings the case about 11/16" down from the top of the case. It is only a slight scratch and I just wondering what is causing it. The scratch does not appear on any of my Norma 7.7 cases that I resized. I am using RCBS dies.

Any one got any ideas? Would using 8x57 cases be better?

Also, anyone know of a place where I can purchase a small amount of cast bullets for my 7.7's that I can try out. I am going to start casting my own as soon as I finish buying all the equipment I need.

Thanks.

[Robert357]

I have recently acquired a Type 99 and am now reloading for it.  I have a set of Lee dies for my Lyman Turret and Lyman Orange Crush presses.  I also have a Lee Loader for 7.7x 58 Japanese.

I have 2.5 boxes of Norma loaded ammo, 2 boxes of loaded Graff ammo and a bag of 50 Winchester unprimed 8x57 Mauser brass.

My new 7.7 Japanese Norma loaded ammo at about 0.3 inches from the primer end of the case is .477 inches in diameter. My new 7.7 Japanese Graf ammo at the same distance is about 0.471 inches in diameter. My Lee full length resized die Norma brass from a once fired round is 0.471 inches. My 8 mm Mauser unprimed Winchester brass is about 0.463 inches.

Well this explains why the Norma brass took so much effort to full length resize in with my Lee die set, even with lots of Imperial Resizing die wax.

I am planning on doing mostly neck resizing with the Lee Loader (sort of).  Actually, I have been using a combination of traditional dies and the Lee Loader as discussed on the 303 page

http://www.303british.com/

on my MN 1891/30 7.62x54R and it has worked very well in extending the life of my Winchester Metric and Graff brass.  Have reloaded many times an no sign of head separation ring.

When I look at my Graff, Norma, resized Norma, and 8mm shells, what was really interesting was that on the full length resized Norma ammo that I have reloaded once, the shoulder is a bit farther forward than on either the loaded Graff or loaded Norma ammo by about half the distance as the 8 mm shoulder is behind the Norma or Graff ammo. Again, I think this screams out for neck sizing this particular rifle.

It will be interesting to measure some "shot" or fire formed ammo for their diameters near the primer end.   My factory unfired Norma brass has a ring about 0.3 inches from the primer end of the case.  When I saw this on unfired brass, I thought this looks like typical case head separation, but obviously it isn't.  I am wondering if Norma did something in the manufacturing process to cause that.  When I reformed with the Lee full size die, it took incredible pressure on the lubed case, but after the once fired Norma case was resized and then tumbled clean, the ring was gone.  

This doesn't sound like it is your problem, but I thought I would share my experience for someone else wanting to try this.

In looking at everything, I can now see why the 8mm brass is considered such an easy no-trim choice for converting to 7.7 Japanese. The length is very very close and the shoulder is just a shade shorter than the 7.7. This means that it is easy to close the bolt and it should also mean that the fire forming of the case should happen pretty easy and after a few firings the case should stretch the 0.1 mm in length to where a regular 7.7 would be.

At the range when I shot the 20 reformed 8mm mauser cases usign 36.5 grains of H-4895 (starting load) and 180 grain Remington .311 bullets, I had no problems and except for the loads being about 4 inches lower on the target all seemed to be doing OK as compared to the factory Norma rounds.  No gas blow back, no problems, although you could see where a few of the primers had partially backed out of the case head, so the smaller shoulder was causing a modest headspace problem.  I feel that the fire formed brass with a new shoulder position, so this will likely be fixed the next time I use the brass.

[Slamfire]

I once had a model 94 Swede, in order to shot it I had to make cases out of .30-06 brass. It didn't last long because the 6.5x55 has a larger diameter than the .30-06. The same is probably true with the 7.7 Jap, the head is bigger than standard brass.

[Robert357]

You are right about the case head being a bit bigger than the 8mm mauser case I am using, but I have to admit that the variation in size for this cartridge is just amazing me.

If you check out Steve's page on his cartridge dimensions you will see what the "normal" variation seems to run (i.e. all over the place).

http://stevespages.com/jpg/cd77x58japanesearisaka.jpg

I got back from the range and the "fire-formed" 8mm Mauser rounds and the last 10 of my original box of Norma factory rounds all micrometered out at slightly over .472 inches a little bit down from the primer end of the case.

I used a Lee universal deprimer to deprime my 20 8mm reformed cases and my 10 Norma 7.7 once fired cases.   Then I ran them through my Lee Loader to neck size them all.  Then tumbled them clean, cleaned the primer holes, debured the primer flash holes, and primed them.  I also carefully inspected them all.

You can see where the shoulder got partially bumped up on the 8mm rounds and where the case got expanded near the primer end or case head.  I checked a sample with a bent paperclip for case head separation ridges and found none.

Now I will do a Ladder work-up using H-4895 in 0.3 grain increments from 36.5 grains to 44.0 grains (with 174 grain Hornady bullets & winchester large rifle primers), using the Norma cases for the loads closest to max powder loading.    Hopefully, that will help improve the accuracy, which is fine at the moment from a hunting perspective, but not quite what I want for this rifle.

[Robert357]

I got back from the range.  My chamber is cut large in my Model 99.
Full pressure fired brass is about .474 to .477 inches in diameter at the case widest point, a ways up from the case head.  This will be difficult to full length resize down to .471.  So I am glad to have the neck resizing equipment.

I now suspect that the box of "new unfired" factory Norma rounds I got with the rifle, had really been previously reloaded.  Another "buyer" be wear lesson!  Shooting someone elses reloads is not something I would have wanted to do.  

I checked all cases, 8mm and Norma 7.7, with a bent paperclip and no internal case head separation ridges were noted.  All primers looked good. None backed out and none were excessively flattened.

My twice fired 8x57 mauser brass did very well.  The shoulders look nicely formed, but the neck is just a mm shorter than the Norma brass.  I did a ladder type work up from 36.5 to 44 grains of H-4895 with Hornady 174 g bullets.  Kind of interesting the Hodgdon powder and Lee Reloading manual say max load is 40 grains of H-4895, while Hornady says 43.9 grains of H-4895 is the max load.  Kind of amazing how different different folks view things.  In my work up, I examined every case for overpressure signs after I fired it.  Even took a caliper and paperclip to the range with me.

I found no overpressure signs at 44 grains of H-4895 in my "loose" Model/Type 99 rifle.

In the ladder test or load work up, I shoot 26 rounds at 100 yards with iron sights.  All but 6 rounds were within a 7 inch circle and that was with almost every round except four fowler rounds being a different powder amount.  some three shot groups where powder varied by .3 grains each apart were touching holes.  One 8 shot string of consecutive powder levels (delta of 0.3 grains) was all within a 3 inches circle.  

I found 3 nice barrel vibration node points for this particular rifle at 38.0, 40.1 and 41.6 grains of H-4895.  Based on this, and the Hodgdon Power and Lee Reloading Manual suggestions of a 40 grain max load for H-4895, I will use 40 grains as my standard load with Hornady 174 grain, 0.312 inch diameter bullets.

Next step will be to experiment with OAL.  But considering how well this thing likes to put the bullets in basically the same place, I am pretty pleased already.  It will be definately hunting accuracy now that I have settled on a single powder weight.

Again, the barrel on my Arisaka has been cut down and recrowned, so results may vary depending upon your rifle's exact configuration.

Bottom line is that reforming from 8x57mm virgin mauser brass, is a nice and easy approach to getting ammo for the 7.7x58mm Japanese rifle.  It does involve use of full length resizing dies and fire forming the shoulder to move it a bit forward.  In my original  8mm brass loading, I had to work the action two to three times for each round to make sure that it got latched by the extractor.  After the fire forming with the shoulder moved forward, the second time I shoot the brass, the extractor grabbed the reformed 8mm brass.

I hope this helps others who might have a type 99 in the closet and wanted to shoot it, but couldn't find ammo.

[ricciardelli]

Graf's has 7.7 Jap brass...and the price is reasonable.

[Robert357]

Steve;

Thanks for the suggestion, and yes it is much better to use brass with the right headstamp and dimensions.

Last time I looked (I placed an order with Graf & Sons for some loaded 7.7 x58 and the 8mm mauser brass I am reforming),  they were out of stock on the 7.7x58 brass.  The order I placed was 3 weeks ago, so they may have gotten some in recently, but what I saw was that it was out of stock.  That is why I bought some loaded ammo and some 8mm brass.

I also ordered for a friend some Graff & sons ammo last year around Thanksgiving as a Christmas present, when it was out of stock and it took over 4 months for it to finally arrive.  That is also partly, why I decided to form some cases.  My experience with them is that when they say something is out of stock, it could be many months before they get it in again.