Does anyone have some data on reloading 303 British with IMR 4227 powder ? I have looked on line but not found any info , I am loading a Hornady 150 grain bullet ( PSP) and using CCI 200 primer , starting load would be great or any info ................thanks Joe
Help Needed .....reloading 303 British
- Thread starter joe.l
- Start date
BattleRife
CGN Ultra frequent flyer
- Location
- of No Fixed Address
What kind of velocity are you expecting?
IMR 4227 burns pretty fast for .303. It might work for a plinking load with a cast bullet, but if you're looking for full velocity from a jacketed bullet, you are barking up the wrong tree.
IMR 4227 burns pretty fast for .303. It might work for a plinking load with a cast bullet, but if you're looking for full velocity from a jacketed bullet, you are barking up the wrong tree.
Incurable Collectoer
CGN Regular
- Location
- Canada, B.C.
I use IMR 4227 to reload for my Long Lees. As BattleRifle mentioned in a .303 Brit this powder is best suited to cast bullets and it will produce a lighter then mil spec load.
IMR4227 is appx 10% faster than IMR4198 and as mentioned is best for cast bullets.
If you're desperate and in a pinch for whatever reason IMR4227 will work in the 303Brit with your 150 grain SP bullets at reasonable velocities, for close range shooting, but IMHO, not acceptable for Deer sized game.
The load I used with a very similar bullet was 32.0 grains of IMR4227, with a Dacron fibre filler, over WLR primers, under 150grn flat base spire point bullets.
Velocities were just over 2300fpx out of a 23 inch No1 MkIII barrel.
I increased the powder charge to 35.0 grains, with a Dacron fibre filler, WLR primers and velocities increased to appx 2500fps.
Both of these loads are on the HOT side, but were SAFE IN MY RIFLE.
This powder is fast and there isn't much room to experiment with. None of the loads I suggested above should be reduced more than 3.0 grains and the Dacron filler needs to be in place to keep the powder charge against the primer flash hole.
Dacron is available at the local fabric shop. It comes in half inch thick, by 3ft wide bolts. A single yard of this fibre will last a lifetime.
I cut it into half inch squares and push it down on top of the powder.
Some folks get their panties in a knot over this practice, claiming it will increase pressures. Maybe, but if you're that close to maximum to worry about it, the load likely is borderline safe anyway.
If you can find a more suitable powder get it. If you can't afford another powder, try to trade what you have for something more suitable.
IMR4227 works best in cases with appx half the capacity of the 303Brit and you can run into some serious issues if you don't hold that powder against the flash hole.
I had much better results with the 125 grain bullets
If you're desperate and in a pinch for whatever reason IMR4227 will work in the 303Brit with your 150 grain SP bullets at reasonable velocities, for close range shooting, but IMHO, not acceptable for Deer sized game.
The load I used with a very similar bullet was 32.0 grains of IMR4227, with a Dacron fibre filler, over WLR primers, under 150grn flat base spire point bullets.
Velocities were just over 2300fpx out of a 23 inch No1 MkIII barrel.
I increased the powder charge to 35.0 grains, with a Dacron fibre filler, WLR primers and velocities increased to appx 2500fps.
Both of these loads are on the HOT side, but were SAFE IN MY RIFLE.
This powder is fast and there isn't much room to experiment with. None of the loads I suggested above should be reduced more than 3.0 grains and the Dacron filler needs to be in place to keep the powder charge against the primer flash hole.
Dacron is available at the local fabric shop. It comes in half inch thick, by 3ft wide bolts. A single yard of this fibre will last a lifetime.
I cut it into half inch squares and push it down on top of the powder.
Some folks get their panties in a knot over this practice, claiming it will increase pressures. Maybe, but if you're that close to maximum to worry about it, the load likely is borderline safe anyway.
If you can find a more suitable powder get it. If you can't afford another powder, try to trade what you have for something more suitable.
IMR4227 works best in cases with appx half the capacity of the 303Brit and you can run into some serious issues if you don't hold that powder against the flash hole.
I had much better results with the 125 grain bullets
hatman1793
CGN Ultra frequent flyer
There is an outstanding article in the NFA Firearms Journal, May/June 2022, on reloading for the 303 cartridge.
I am using N540 in my 303 brit with good results.
Varget, RL16 are others that will work great as well.
On a side note, it your want to get rid of your imr4227, I am on the hunt for some. Depending on where you are located, I may have some varget to trade.
Varget, RL16 are others that will work great as well.
On a side note, it your want to get rid of your imr4227, I am on the hunt for some. Depending on where you are located, I may have some varget to trade.
Go to castpics net and try to download the old IMR Guides. Mine doesn't show .303 but has .30-40 Krag.
An old Hodgdon Data Manual from 1986 gave 17 gr of their H4227 in .303 with both 150GC and 180GC bullets (1600 and 1550fps); 16gr in the 30-40K gave 1419fps with a 180gr GC.
If your powder was made in Australia, it is H4227 packaged as IMR.
An old Hodgdon Data Manual from 1986 gave 17 gr of their H4227 in .303 with both 150GC and 180GC bullets (1600 and 1550fps); 16gr in the 30-40K gave 1419fps with a 180gr GC.
If your powder was made in Australia, it is H4227 packaged as IMR.
