Factory Second Bullets 303 Caliber and 7.7mm Japanese

Attachment 134913

I'm finally getting around to loading up some ammunition for the Arisaka Type 99 carbine I bought in March of 2023. It came with 100 once-shot Norma brass just needed some projectiles.

I was looking around MidwayUSA and noticed they had Factory Second Bullets 303 Caliber and 7.7mm Japanese (3105 Diameter) 174 Grain Full Metal Jacket Boat Tail for $35.00 for 100.

Being the couruios type, Aka Test Engineer, I am I wanted to see what the deal is with these bullets. I was curious about what makes them 2nds. Not knowing who the manufacturer limits what I can learn since I have no reference bullet or complete manufacture specification to compare what the projectiles are.

So really, all I can learn is what the variance is;
1.) In weight
2.) In Diameter
3.) In Ogive to Base

And, of course, after working up a decent load, how well do the bullets work (out of my Arasaka)

So far, I have learned:

1.) Only 43 of 100 projectiles weight are within the advertised 174.0 grains (+/- in 0.1 Grain)
2.) The Average Ovige is 0.618" (+/- 0.0001)
3.) The Diameter is almost a 50/50 split 0.3106"/0.3107" and more than the .0.3105" advertised by MidwayUSA.

So what does it all mean so far?

• For enjoyment shooting (plinking), these projectiles should work just fine; how much they vary in the three measurements should have little impact on the accuracy of my rifle at my intended shooting distance of 100 yards.
  
• These seem to be an excellent deal for the price, and I'm glad I bought two boxes.
  
• I can't wait to see how these perform.

After test shooting many different loads in over 200 T-99 rifles , I found that bullet to be about the worst for accuracy .

Thanks for posting. I look for 7.7 Arisaka postings because I have been working on such test loads myself. Please let me know what your results are. These look like 174gr Hornady bullets. I'm testing with these bullets as well. But, my the time start fine tuning my loads, I have to change powders! I am trying AA4350 now. A few months ago, I acquired 100 Norma cases like yourself and am resizing them now. I size my cases and trim them to just under chamber length so the bullet ogive can touch the lands. Use a Sinclair chamber length gauge. Instead of using the sizing button, I size the case and use a mandrel. Are you using an unaltered rifle or do you have s sporterised rifle with a scope? Mine is unaltered and I use a large radiation sign triangle to line up my sights.

It's the "boat-tail". (and the bullet diameter.

.303Mk7 and 7.7 Jap did NOT have "boat-tailed" bullets. The bullets were (generally more than .3105" as well. I have not "sampled" many Arisakas, but, the "nominal 7.7mm indicates a BORE of approx .303". This is not surprising, as the Imperial Japanese Navy was heavily based on BRITISH practice and equipment. Their first "proper" machine-guns were chambered for .303, but the local product was designated 7.7mm. In front of me right now is a specimen of this rimmed "7.7" cartridge that looks exactly like a Mk Vll .303, complete with "stab" crimps on the neck, the headstamp is the giveaway, as is the slightly domed primer cup. the "discolouration on the case indicates that it spent a LONG time, possibly a wet time, in a metal "strip' as used in Hotchkiss" based MG designs.

If anyone has a good Type 99 rifle or one or more of the 7.7mm machine-guns lurking about, it would be nice to get some "GROOVE" diameter readings.

See also the ballistically similar 7.65 Belgian / Argentinian. I am not really a cartridge "collector, so, I do not have samples of the other two (rimless and semi-rimmed) Japanese 7.7mm cartridges.

Quote:

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Originally Posted by Bruce_in_Oz

If anyone has a good Type 99 rifle or one or more of the 7.7mm machine-guns lurking about, it would be nice to get some "GROOVE" diameter readings.

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Bruce, Not sure what you mean by "GROOVE"

Bill

---------- Post added at 02:43 PM ---------- Previous post was at 02:40 PM ----------

Quote:

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Originally Posted by BJung

Are you using an unaltered rifle or do you have s sporterised rifle with a scope? Mine is unaltered and I use a large radiation sign triangle to line up my sights.

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I'm using an unaltered rifle that was a bring back. I've not had the chance to take it to the range with the ammo I loaded for it yet.

"Not sure what you mean by "GROOVE""

https://www.milsurps.com/attachment....34&cid=1&stc=1

The military 7.7mm Arisaka bullet is right at .310 and the groove can be between .312 to .316 [ same for most .303's ] . The average WWII British .303 bullet is about .3095 . Both are bore riding bullets with a flat / exposed lead / hollow base to expand and seal the bore . With a small dia boat tail bullet accuracy is lacking , even at 100 yards . But in stock form with original sights it is very hard to shoot a t-99 Really well with about anything . In our 15+ years of every weekend military rifle matches we have great accuracy from most military rifle types , except the Enfield and T-99 . They just could not shoot on the level with the others and people quit shooting them , they could do about 3 to 4 inch 5-shot groups at 100 yards on demand , but in our matches that was not good enough for a win . . We had to hold matches just for them . But then again most people will not shoot at that level and will be happy with the results .

Quote:

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Originally Posted by Bruce_in_Oz

If anyone has a good Type 99 rifle or one or more of the 7.7mm machine-guns lurking about, it would be nice to get some "GROOVE" diameter readings.

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Bruce,

I slugged the barrel on my Type 99, and the Grove is .315" and Bore Dia is .302" - I slugged it twice and got the same measurement using my Mititoyo calipers, which have a +/-0.001 in tolerance.

I have some questions some of you may know and help many of us. First, I slug my T99 barrel and from the diagram, the diameter of my slug measures .3115". From the diagram above, this is the groove diameter and many refer this as the bore. From my measurements, the best bullet diameter should be .312 or .3125. Yet, I've come across other shooters that claim that a .308" bullet will expand to .312". Would this depend on the type of bullet? Would a Sierra bullet expand easier than Speer, Hornady, Winchester.. because of the lead core alloy? Or, are these shooters missing something that I just noticed? The groove diameter might vary but the bore measurement is the same, that is why a .311 bullet or .308 bullet can still be shot through a T99. By chance, the Speer .311 doesn't shoot well through my T99. Hornady is better. What bullets are used most on shooting competitions with Enfields and T99s? Sierra or Hornady?

1. It looks odd because it's "Metford" rifling, featuring rounded grooves.
2. All those bullet brands normallly feature gilding metal (copper alloy) jackets with lead cores. Few of them expand on firing to fill the grooves - despite a lot of wishful posting on the web.
3. Best results can be expected from bullets with flat base and not more than ~.002" under measured groove diameter.
4. Boattail bullets offer less bearing surface than FB of same weight, making them a challenge in military chambers with generous throats. (They can yaw before engraving).


https://www.milsurps.com/attachment....87&cid=1&stc=1