303/243 load Data with ADI Powders

[smlekid]

Hi guys I'm looking for any load Data for a No1 Mk111 Lithgow in 303/243 I can't seem to lay my hands on my older loading manuals I guess I have put them somewhere safe. We run a classic sporter event that is open to No1 rifles in any calibre based on a 303 case. It's a good fun shoot targets can be anywhere out to 300m

[No1Mk3]

Cyril Waterworth (1970) gives data for this cartridge but with older powders, DuPont 4320 and 4350 are not exactly the same as IMR 4320 and 4350, same as Norma 203 and 204 then is slightly different to current batches. 303/25 data is the same for bullet weight. If you want to name your bullet weight I can give you what is in the book but advise you start 5% under and build up

[smlekid]

Thanks No1Mk3 I will likely be using in the 70 to 90gr range. I do load for a 303/25 kind of suspected they would be close in powder weight. I mainly use 2208 with 87gr Speer TNT's in my 303/25. I have Cyril's vook here somewhere just can't find it

[Bugman]

Just out of curiosity, have you checked with ADI? They "may" have some helpful data.

[bladeracer]

Hi guys I'm looking for any load Data for a No1 Mk111 Lithgow in 303/243 I can't seem to lay my hands on my older loading manuals I guess I have put them somewhere safe. We run a classic sporter event that is open to No1 rifles in any calibre based on a 303 case. It's a good fun shoot targets can be anywhere out to 300m

Nick Harvey's first edition has a page for it.
Interestingly, he doesn't say to reduce the data 10% for Lee Enfields (as he does the other .303 wildcats), but I still would.

303-243 data.jpg (129.06 KiB) Viewed 81 times

Personally, I would use AR2206H (H4895), start low and work up. I'd start around 28gn behind an 87gn bullet.

[No1Mk3]

243-303 Waterworth 2.JPG (500.95 KiB) Viewed 75 times

243-303 Waterworth 1.JPG (520.95 KiB) Viewed 75 times

Page from Waterworth

[smlekid]

Thank you all I have at least an idea now

[straightshooter]

There is a way to come up with modern powder load data and it's not rocket science.
The 243/303 case has a water capacity of 53 grains compared to a 243 Win which has 54 grains so they are pretty close in internal volume.
So if you pick any ADI starting load for a 243 Win and reduce it by 2 grains you should have a safe starting load for further development if you are so inclined.
Under no circumstances increase your load to the starting ADI 243 Win load due to the pressure limitations of a SMLE.