Boat tails for 6.5 and 7.7 Jap

[HasegawaYamato]

Please dont snap my head off here... Im completely new to reloading, just got few Japanese rifles and found it diffcult to get factory ammo...
Did some research, found some saying these jap guns dont like BT rounds, some saying there are no notable difference. Is this something depends on the gun itself or there are some other factors?
Thanks!

 

[cosmic]

No - Flat based bullets generally shoot better in milsurps. I would take that a step further and say that flat based bullets generally shoot better that non-match grade boat tails in most rifles. Only your rifle knows for sure...

 

[Ganderite]

I have found that it is a matter of barrel quality. Only quality barrels in good shape shoot BT well. A flat base is a much safer bet in a milsurp.

 

[mbogo3]

Do then not have elliptical rifling at least the 6.5's ? Is the 7.7 Enfield style rifling?

 

[bigedp51]

Boat tail bullets can have accuracy problems in milsurps with a worn muzzle and crown. If the muzzle is not perfect the escaping gas can push on the boat tail off the axis of the bore and slightly deflect the bullet. And the flat base bullets are not affected as much as the boat tail bullets are by the uneven escaping gasses.

The British .303 Mk.8Z bullet used in machine gun ammunition was a rebated boat tail design that improved barrel life and was less affected by a worn muzzle.

Below explains the improved accuracy and barrel life with rebated boat tail bullets.

Another factor with flat base bullets when fired and kicked in the backside is they would expand and fill a worn oversized bore improving accuracy.

Below is a 1943 No.4 Enfield with a two groove barrel with a very worn muzzle, and you can not see any rifling in the last 1/2 of the barrel. But the accuracy was still very good when using the Hornady .312 174 grain round nose bullets. But if a boat tail bullet was used the group size would expand to over three inches at 100 yards.

The standard ammunition in the Enfield rifles had a flat base bullet, and flat base bullets are the best choice for old worn barrels.

 

[mbogo3]

https://www.milsurps.com/showthread.php?t=44102

 

[HasegawaYamato]

Thanks guys! I will try to find some flat base then!

Boat tail bullets can have accuracy problems in milsurps with a worn muzzle and crown. If the muzzle is not perfect the excaping gas can push on the boat tail off the axis of the bore and slightly deflect the bullet. And the flat base bullets are not effected as much as the boat tail bullets are by the uneven ecaping gasses.

The British .303 Mk.8Z bullet used in machine gun ammunition was a rebated boat tail design that improved barrel life and was less effected by a worn muzzle.

Below explains the improved accuracy and barrel life with rebated boat tail bullets.

Another factor with flat base bullets when fired and kicked in the backside is they would expand and fill a worn oversized bore improving accuracy.

Below is a 1943 No.4 Enfield with a two groove barrel with a very worn muzzle, and you can not see any rifling in the last 1/2 of barrel. But the accuracy was still very good when using the Hornady .312 174 grain round nose bullets. But if a boat tail bullet was used the group size would expand to over three inches at 100 yards.

The standard ammunition in the Enfield rifles had a flat base bullet, and flat base bullets are the best choice for old worn barrels.

Really appreciate for the detailed explanation! The British bullet seems quite nice but why are they discontinued?

 

[bigedp51]

Thanks guys! I will try to find some flat base then!

Really appreciate for the detailed explanation! The British bullet seems quite nice but why are they discontinued?

The .303 British military cartridge is no longer used by the British or commonwealth *military. But Lapua makes rebated boat tail bullets in many calibers.

There are still countries making the .303 British cartridge for military use. It is my understanding that Prvi Partizan fills military contracts for countries still using the .303 British cartridge.

Below the standard British .303 used in the Enfield rifle with a flat base bullet. Machine guns used the rebated boat tail bullet and cooler burning single base powders.

 

[HasegawaYamato]

The .303 British military cartridge is no longer used by the British or commonwealth *military. But Lapua makes rebated boat tail bullets in many calibers.

There are still countries making the .303 British cartridge for military use. It is my understanding that Prvi Partizan fills military contracts for countries still using the .303 British cartridge.

Sorry for the confusing question, Im curious why no other militaries use such bullet design, even for Britain itself? like the following experimental .280 British or 4.85X49... If I realled it right the .280 is flat base and 4.85 is conventional boat tail...