Looking for Good cast 7.7 Loads

[Old Ranger]

Both my nephew and I have picked up Type 99 Arisaka's in the last few months. We are trying to find a couple good cast loads. We have been using Ideal 311299 sized 314. Cast from WW plus 2% tin and water quenched. I have tried both shortened 3006 and 8x57 cases.

Have tried 22.0 grs of H4198, 20 grs of 2400 and 25 grs of 5744. Any loads lighter than these have blowback with nearly every round. (in both rifles). Accuracy has been best (just over an inch at 50yds) with the H4198 but last 10 rds fired had some gas leakage on 7 rds. Sooty necks are common with all these loads. I have been thinking of going a little heavier with the 4198.

I also have IMR 4227 ,SR4959 and Trailboss as well as access to 311284 at .314.

I've had my best success over the years with 4198 and 2400 in a variety of mid caliber military rifles ( 3006, 7.62x54, 8x57, 303Br, 7.5 MAS etc)

Any help would be much appreciated. Arisaka rifles with good shootable bores are not all that commom here in Canada. I feel we both lucked out in that department.

[Outpost75]

The 7.7 Japanese has a case capacity very close to the .303 British, and similar twist, bore and groove dimensions, however the Japanese rifles are VERY strong and robust, so you are unlikely to get into any trouble using any proven load in the .303 British case with similar bullet.

In my .303s a charge of 30 grains of RL-7 or 36 grains of either Varget, RL-15 or IMR4064 give good results with the #314299 and similar, with bullets of suitable hardness which fit the barrel and forcing cone of the chamber.

[runfiverun]

notice he said 314299 not the 311299.
there is a huge difference in their nose diameters.
the 314 does alright in oldestgirls 7.7 it prefers a 314 diameter loverign design that gets out there and fills things up.
the 5r [metford] type rifling needs diameter and bhn to work it's best, just like the microgroove barrels do.

[Old Ranger]

Clarification on the mold we are using. It is an Ideal single cavity marked 311299. It casts about 313.5 on the body and 303 on the nose. Gas checked and lubed in a 314 die.

[3006guns]

It's well known that the 7.7 cartridge case is larger at the base than either the '06 or 8mm, so I would recommend neck sizing after the first firing. The Prvi 7.7 cases fit beautifully (hint, hint).

Is it possible that the cases are too hard in the neck area and not expanding completely? Are you making cases from commercial or military brass. Some of the military stuff is a lot harder than you might think.The reason I ask is that I've had sooty necks when using mild loads of Unique, but in Norma 7.7 cases. I gave them a quick neck/shoulder anneal and that seemed to stop the sooting.

[Nickle]

You should anneal your case necks anyways, first initially, then periodically thereafter. Not so needed, if you use Wilson hand dies that don't expand the neck, but still need to rarely with them.

If in doubt, anneal. If you just formed cases, anneal before loading.

[frnkeore]

Most '06 loads should work fairly well in the 7.7 as the capacity is close (4.1cc Vs 4.4cc for '06). 20 gr of 4759 is a excellent '06 load and holds the 300 yard CBA record. Start at 18.5 and work up. Make sure at the bullet is at least touching the lands and use pistol primers to start (Rem 2 1/2 are best).

Frank

[Old Ranger]

Good input gentlemen. Thanks! My nephew had the same train of thought about brittle case necks. He has annealed some cases and is going to try the 4198 loads again. We are using commercial cases.
SR4759 is what I planned on trying next

[bruce drake]

I second the use of 303 Brit data. I've got 2 Type 99s and I use the cast data for the 303 Brit in the Lyman Cast Bullet handbook for my cast loads simply for the higher amount of recipes. I use 7.65 Argentine data for my jacketed data to pump the pressure up past the 303 Brit pressure level limits imposed by the English No. III and No. 4 actions. If you get a load manual that separates their 303 Brit loads for P14 rifles than those loads will work fine in the Arisakas.

Bruce

[punk427]

I firmly agree with the information you've got. reforming 3006 brass works just fine, I would CERTAINLY anneal. it only takes a few minutes with a plumbers torch. Make sure you fire form. You can use unique, clays, red dot, even trailboss would be fine. just a light charge, for IE: I fire form mine with 8 gr of unique. the 314299 is IMO the better boolit for this cartridge. and yes the 303 british and 7.7x58 are close enough to call identical. For my loads I use the 314299, and 18.5 gr of IMR SR-4759 and an COAL of 3.090. However considering your reforming to a diff caliber, I would suggest using all the same headstamp as they differ in capacity and im sure were using different primers. for IE: I used the greek milsurp m2 brass headstamp HXP, I have a bunch given to me and had exactly 50 of 1978, so when ever I see HXP 78 I know there not m2 anymore. and start low and work your way up sence cases do differ that much, Id start with like 16 gr of sr4759 and work up to where its good for you with 24 gr being max.

another idea would be to try a magnum primer with which ever load worked best for you.

[frnkeore]

As far as the 7.7 x 58 having a simular case capacity to the 303 brit. It just isn't so. It's much closer to the '06.

Using 303 data would give lower pressures and velocity but, reducing '06 data by 10% would give more accurate predictions.

My fired HPX cases are 3.544 cc (54.7 gr water), My 2 Norma 7.7 x 58 cases average 4.21 cc (65.0 gr water) and my '06, LC, 60 match cases are 4.46 (68.8 gr water). The 7.7 is 19% larger than the 303, where as the 7.7 is 6% smaller than the '06.

The capacity's I gave in the earlier post were from a cartridge conversion book (Donnelly). These are actual measurements of cases that I have. The Hxp 303 brits were fired in my P14.

Frank

[TCLouis]

According to at least one chart, 06 is 4.38 cc and 7.7 is 3.47 cc 3.28 cc capacity, and according to my calculator, that is 79.2 %. Case capacity is 69 for 06 and 60 for the 7.7 and 57 for 303 British according to numbers I pulled from a chart in the NRA handloading book. I always use this info to ratio load data which is 86.9

I know someone that has used that ratio and though they tested lower and higher found several accurate loads in the 06 that ratioed to be the same in 7.7X58. YMMV Considerably because they can also use .310" cast in theirs just fine and .308" fully coated.

That said I understand that they annealed a bunch of cases after forming and trimming and placed the 150 GB and 165 RD GB boolit in front of 7.1 and 7.5 grains of Bullseye to fireform the cases. Rumor is that they got under 1" (outside measurement) for 5 shots at 50 yards. The story is they have about 150 cases to go to finish fireforming their supply.

They claim that they may try annealing then forming and also cutting to some length, annealing and then final trimming in the future.

In their gun the chamber is slightly larger than 30-06 base, but the way their sizing die is, (RCBS and Lee) the die is undersized and works the base on the case every time, Including the 7.7X58 Norma brass they have. All their dies seem to be under chamber dimension. No they have never miced a case after firing, just loaded and shot. 4-5 loadings and cases formed and shot without annealing begin to get neck splits. They annealed all cases after forming and trimming this go around so we will see if it extends case life.

Holy Moley, he shot a 150 GB FP boolit into a 1 gallon milk jug full of water with the fireforming load and it opened it up, but 15.0 grains of 10B101 and the 150 grainer flat blew the jug open spraying water far and wide. Gonna have to chrono that load.

[303Guy]

I use 7.65 Argentine data for my jacketed data to pump the pressure up past the 303 Brit pressure level limits imposed by the English No. III and No. 4 actions.But the 7.65 Argentine is a ballistic twin of the 303 Brit, intended as such. Why would the reloading manuals give it as higher pressure loads? The actions are stronger yes, but the loads normally shown equal the Brit. I've only access to Hodgdon's data so I don't know what others show. Just curious.

Does anyone use Ammoguide? There may be some loads there but accuracy is not indicated, neither is pressure.

[TCLouis]

303 Guy . . . I'm guessing that the difference in loading data is due to the perceived strength of the guns the cartridge is typically chambered in.

[303Guy]

Well, the Brit should not be loaded hot. But apparently the Argentinian should not be loaded hot either. It's to do with the small ring and the steels used in those days I think. But for cast, the action is not the limiting factor. What I'd like to know know is just how the capacity affects the pressure curve of cast loads when powders like Unique, 2400 and 4227 are used. Aren't there 'universal' loads with these powders that work across the board?

There are some cast boolit loads given in AmmoGuide Interactive but only for 2400 and IMR4227. If one subscribes, you can add your loads. Non subscribers cannot view load details though. I'm a subscriber.

[Cosmiceyes]

Most '06 loads should work fairly well in the 7.7 as the capacity is close (4.1cc Vs 4.4cc for '06). 20 gr of 4759 is a excellent '06 load and holds the 300 yard CBA record. Start at 18.5 and work up. Make sure at the bullet is at least touching the lands and use pistol primers to start (Rem 2 1/2 are best).

Frank
Using a mid range 150 boolit in a 30-06 loaded with IMR 4350 out of the manual lowest charge is 50.4 grains; for the 7.7 using a 150 grain boolit the "MAX" is IMR 4350 47.7 grains. Do you see the problem?

[frnkeore]

My Pacific manual gives 50 gr 4350 max with a 150 gr jacketed, 46 gr for a 180 gr.

My Lyman #44 gives 54 gr max for 4350 with a 150, 51 gr for the 180 gr.

My NRA Handbook lists 53 gr 4350 for 150's and 50.5 for 180's.

The 99 Jap is one of the strongest actions in the world and if in good shape, doesn't need to be loaded down.

My original suggestion was "aimed" at cast bullets and NOT jacketed.

If you reduce '06 CAST bullet loads by 10% you will be EXTREMELY safe and will produce velocitys a lot closer to actual than using 303 data.

That said, you have to tell me how a case that has a capacity 19% greater than the 303 can produce the same or even similar velocitys and pressure to the 303.

Frank

[roberto mervicini]

7706777068

I reload 7.7 jap. using 06 brass resized in 7.7 FL die and trim to length. Above a 5 shoots group using Hornady 150 gr.Spire over 46.0 gr. of IMR 4895, the lower 10 shoots group are Norma 180 gr. factory load, no scope adjustment made during the test, just aiming dead center.