303 ammo questions

[gemite]

I have 3 old 303 cartridges. I have questions about the first 2.

The first cartridge has the same case length and the same case rim diameter as the other two but the shoulder is set back approximately 1/16". The headstamp is below.

I believe it is from the Dominion Cartridge Company, loaded with cordite, and is a mark ii. I would like someone to confirm what this cartridge is.
The next cartridge has a flat nosed lead bullet and has the following headstamp

I believe it is from the Dominion Arsenal Quebec made in 1916 but I am not sure what the GP or B mean.
Finally I believe that I have a cartridge from Dominion Arsenal Lindsay Ontario made in 1918 and it is a mark vii.

I would appreciate any information on these cartridges.

 

[plinker 777]

Just a guess, but I believe the first two are what are referred to as "gallery rounds". These were used for training purposes and are not a full cordite load. Yes they are collectible (don't shoot them).

 

[green]

1) is a gallery practice MkI black powder loaded on a reloaded MkII ball case made by Dominion Arsenal. It is loaded with 9 gr BP. The shoulder was set back to allow the fitting of a wad under the bullet.
2) is a gallery practice MkII smokeless made at Dominion Arsenal loaded with 5.5 gr smokeless. The bullet nose has been cut off.
3) MkVII made at Dominion Arsenal Lindsay.

 

[gemite]

Thank you both for the info.

 

[gemite]

How many grains do the lead bullets weigh in the gallery cartridges?

 

[green]

MkI BP and MkI smokeless 90 gr
MkII smokeless 125 gr

 

[gemite]

Thank you. Some day I would like to reload a modern version of the gallery load to try.

 

[plinker 777]

^ I've been told that a projectile and powder load from a 7.62x39 in a .303Br case is a close replication of the gallery load. It will have more "umph" than 9 grains of BP, that I can assure.

 

[howard2]

I have used a 32 auto bullet and 7 grains of Unique. Make a great light round.

 

[stevebc]

MkI BP and MkI smokeless 90 gr
MkII smokeless 125 gr

Interesting- BigEdP51 uses a 100gr pistol bullet and Trail Boss to fireform his brass, and based on that, I'm working on a load for 85gr. pistol bullets, also using Trail Boss. I've tested out several loads in the 12 to 16 gr range, and found even the hottest at 16.5 gr was a fairly soft load. I'm new to TB, but find it reminds me somewhat of black powder ie smoky and softer than say, Varget or IMR4895.

I'd have no problem describing it as a 'gallery load".

ps to Howard- I'm also using a .32 cal bullet- the Hornady XTP .312.

 

[gemite]

I just purchased the Lee TL314-90-SWC mold today. Hopefully tomorrow I can cast some bullets and reload using the above recipes for unique and trailboss.