Thread: 303 MK7 load data?

Yes you need seperate brass for each SMLE as the chamber's vary quite a bit between rifles.some fired cases look nothing like unfired ones.... If donor brass has been fired in bigger chamber it won't fit... If in smaller chamber it will but will grow heaps on fireing. Think of it like a std vs akly improved chamber.

Originally Posted by Crusty

Use Lee collet dies and only neck size - the brass will last a lot longer. I've had more than 10 reloads out of my R.P brass

Ive been reading that some are reporting 20 reloads neck sizing only using high quality brass if done right.
It also appears that the no4 mk1 rifle is way worse when it comes to this compared to a no1 mk3.

Too bad ive resized all this HXP, but i had no option with my lee die set. I will probably use these rounds in another rifle anyway, so probably wont matter one off. I need to look out for one of those lee collet dies if anyone has one spare to sell.

Originally Posted by Micky Duck

Yes you need seperate brass for each SMLE as the chamber's vary quite a bit between rifles.some fired cases look nothing like unfired ones.... If donor brass has been fired in bigger chamber it won't fit... If in smaller chamber it will but will grow heaps on fireing. Think of it like a std vs akly improved chamber.

Yes I just need to get a good amount of brass and reload accordingly, I can colour code the primers with varnish to identify them, etc.

Originally Posted by Old_School

Ive been reading that some are reporting 20 reloads neck sizing only using high quality brass if done right.
It also appears that the no4 mk1 rifle is way worse when it comes to this compared to a no1 mk3.

Too bad ive resized all this HXP, but i had no option with my lee die set. I will probably use these rounds in another rifle anyway, so probably wont matter one off. I need to look out for one of those lee collet dies if anyone has one spare to sell.



Yes I just need to get a good amount of brass and reload accordingly, I can colour code the primers with varnish to identify them, etc.

Not hard to set up your die to neck size only
303 is a fairly easy calibre to load for
Let us know how you get on

Originally Posted by Old_School

@grandpamac Another thing that come to mind, I was told that ideally with 303 in particular, due to sloppy machining in the chambers, etc that its best to only do neck sizing and not do a full length resize, as it shortens the life of the cases if done too much.
Is this something you recommend?
If i go down that path however, I believe that you should only continue to use that ammo in the same rifle you shoot it with, so would mean I would need to seperate them for use in different rifles?

Greetings @Old_School,
I load all of my old soldiers using reduced loads and neck sized cases. I use a Lee Loader for depriming and neck sizing. Both of my current .303 rifles are scoped so there is no problem with sight adjustment. Previously I had bee using reduced loads and neck sized cases in my .308 for 4P shooting at 100 metres with 38 or 40 grains of AR2206H with 150 grain projectiles so when I needed an iron sight rifle was needed I used a No4 rifle with a Parker Hale sight. The barrel was in reasonable condition other than an eroded throat and chronographed a little over 1,900 fps with 40 grains of older AR2209 and the 174 grain RN in neck sized cases. The two current .303 rifles here both have near new barrels wit a crush fit for projectiles around 5mm shorter than the iron sight rifle. You will need to keep separate batches of cases for each .303. More later.
GPM.

Biggest benefit I find is from frequent annealing.

Originally Posted by Jhon

Biggest benefit I find is from frequent annealing.

Me too,
Some target shooters anneal every firing and I am tending that way. Likely more important is how you anneal, it has to be as near as possible the same for every case in the batch. The AMP annealers, although pricey, are top of the heap. In spite of howls of dismay from some Forum members I still use a candle but if this offends you use a small torch. I hold the case with my fingers around half way up and rotate the case neck in the tip of the flame until the case head is almost too hot to hold. Wipe the case all over with a damp Chux and you are done. You can count 1, 99 etc if you like. This was written up by John Barsness in Handloader a few years back. There are annealers with timers which do the job but I would avoid like the plague any method that includes the words "until it looks right".
Neck sizing can be done with a Lee loader or a Lee collet die as the best options. You can also use a FL sizing die backed the shell holder so that it does not size the case body at all. I found with my .308 that cases that chamber with some resistance will chamber freely after one light load. Rimless cases used for light loads should be kept separate from full load cases as the headspace increases with firing. This is not much of a problem with rimmed cases like the .303.
GMP.

Originally Posted by grandpamac

Greetings @Old_School,
I load all of my old soldiers using reduced loads and neck sized cases. I use a Lee Loader for depriming and neck sizing. Both of my current .303 rifles are scoped so there is no problem with sight adjustment. Previously I had bee using reduced loads and neck sized cases in my .308 for 4P shooting at 100 metres with 38 or 40 grains of AR2206H with 150 grain projectiles so when I needed an iron sight rifle was needed I used a No4 rifle with a Parker Hale sight. The barrel was in reasonable condition other than an eroded throat and chronographed a little over 1,900 fps with 40 grains of older AR2209 and the 174 grain RN in neck sized cases. The two current .303 rifles here both have near new barrels wit a crush fit for projectiles around 5mm shorter than the iron sight rifle. You will need to keep separate batches of cases for each .303. More later.
GPM.

I have a spare fired case of mine and put it in the chamber of some other guns and spare barrels to compare, i see no difference between one rifle and the one that it originally was fired in, along with a spare barrel, but one rifle it was much tighter so i expect that i would have to use a separate lot of brass in this rifle, but for the other two I think I should be able to get away with it.

What part of the case will fail with FL resizing? I take it that the brass splits down the side? I thought the neck would be the first place to fail, but i take it that annealing largely addresses this, can the whole case be annealed at all?

Originally Posted by grandpamac

Me too,
Some target shooters anneal every firing and I am tending that way. Likely more important is how you anneal, it has to be as near as possible the same for every case in the batch. The AMP annealers, although pricey, are top of the heap. In spite of howls of dismay from some Forum members I still use a candle but if this offends you use a small torch. I hold the case with my fingers around half way up and rotate the case neck in the tip of the flame until the case head is almost too hot to hold. Wipe the case all over with a damp Chux and you are done. You can count 1, 99 etc if you like. This was written up by John Barsness in Handloader a few years back. There are annealers with timers which do the job but I would avoid like the plague any method that includes the words "until it looks right".
Neck sizing can be done with a Lee loader or a Lee collet die as the best options. You can also use a FL sizing die backed the shell holder so that it does not size the case body at all. I found with my .308 that cases that chamber with some resistance will chamber freely after one light load. Rimless cases used for light loads should be kept separate from full load cases as the headspace increases with firing. This is not much of a problem with rimmed cases like the .303.
GMP.

Im not sure where I will start with annealing, but I have a gas torch that I can use.
I also believe its important to drop in cold water immediately as part of the process?
I see a bit if discussion about using a FL die to neck size the brass, How many turns typically do you need to back off? I might see if i can get the collet die in the long run.

Originally Posted by Crusty

Use Lee collet dies and only neck size - the brass will last a lot longer. I've had more than 10 reloads out of my R.P brass

This. I'm to 14 on my brass.

Originally Posted by Danger Mouse

This. I'm to 14 on my brass.

Thats pretty good going, i never realised what I was getting myself into with 303 reloading!
Looks like im going to need a fair bit of brass as I have been starting to do quite a bit of shooting at the range and if i use more than one rifle thats going to be a problem for me.
For hunting purposes Im not too worried if i have to full length size the few rounds I will put through it, but im keeping all my rounds at 174 grain and sighted in for that, so no matter what Im shooting, the ballistics will be the same.

Originally Posted by Old_School

I have a spare fired case of mine and put it in the chamber of some other guns and spare barrels to compare, i see no difference between one rifle and the one that it originally was fired in, along with a spare barrel, but one rifle it was much tighter so i expect that i would have to use a separate lot of brass in this rifle, but for the other two I think I should be able to get away with it.

What part of the case will fail with FL resizing? I take it that the brass splits down the side? I thought the neck would be the first place to fail, but i take it that annealing largely addresses this, can the whole case be annealed at all?




Im not sure where I will start with annealing, but I have a gas torch that I can use.
I also believe its important to drop in cold water immediately as part of the process?
I see a bit if discussion about using a FL die to neck size the brass, How many turns typically do you need to back off? I might see if i can get the collet die in the long run.

Greetings,
I don't believe that there is any need to drop the cases into cold water. Early annealing methods included standing cases up to their middle in water and heating the necks with a torch. The reason was to stop the heads of the cases becoming soft and failing when shot. Some suggested tipping the cases over when done. You need to back of the die until the body and shoulder are not touched by the die. This will depend on how big your chamber is. Some trial and error will be needed. A .308 die can sometimes be used without the expander button running the
303 button in and out to expand the neck,
The more you learn about handloading the more complex it becomes.

Originally Posted by Old_School

I have a spare fired case of mine and put it in the chamber of some other guns and spare barrels to compare, i see no difference between one rifle and the one that it originally was fired in, along with a spare barrel, but one rifle it was much tighter so i expect that i would have to use a separate lot of brass in this rifle, but for the other two I think I should be able to get away with it.
n.

. Think about it.... You MAY have used case fired in a tightish/ smallish chamber,so yes it will fit in a largeish chamber....but it won't work the other way around... To partial length resize you EXPERIMENT with how much to back it out till you get it to chamber with just wee bit of resistance....but remember the SMLE is cock on closing with little camming action,too tight is faaarkin frustrating with red hind looking at you fifty yards away....

Quote: "What part of the case will fail with FL resizing? I take it that the brass splits down the side? I thought the neck would be the first place to fail, but i take it that annealing largely addresses this, can the whole case be annealed at all?" Endquote.

First never anneal past the shoulder. If you do you will tend to get unpleasant results like case length crushing when you seat bullets.

Second, if you anneal the case neck you extend the reload life of the the case and enable correct neck tension on the bullet. If the brass is too brittle and hard it not only splits but it springs back when resized so neck tension is less and not uniform case to case.

Third, the case will eventually fail if not from neck splits then two other things. If full house loads the primer pockets eventually won't hold a primer tight. Same in all cals..with 303B brass, before primer pockets fail you are likely to get case head separation. Especially if you FL.size for a generous chamber and larger headspace dimensions. To check for incipient head separation use a thin wire, folded out paper clip, with a small hook bent on one end. Insert in case head and draw forward, hook against case wall. A short distance from the head, maybe 4-5mm, you may feel the hook catch. The brass has thinned here forming an internal groove. On the outside opposite the groove you can usually discern a shiny ring. If either it is time to discard the case or risk it rupturing and separating head from body the next time you fire it. 303B brass is well known for this. Not such a problem if you are loading down and neck sizing. Primer pockets dont stretch as much either.

The cases only tend to split down the side if the brass is old, rotten or really tired and brittle. Hot loads will do this with old brass like some of the HXP and old 1940s-50s CAC etc. Young brass like factory PMC, Hornady etc likely won't give you side splits. You'll get split necks, case head separation or loose primer pockets prior. Long life for 303B comes from good brass, annealing, neck sizing and modest charges.

Originally Posted by grandpamac

Greetings,
I don't believe that there is any need to drop the cases into cold water. Early annealing methods included standing cases up to their middle in water and heating the necks with a torch. The reason was to stop the heads of the cases becoming soft and failing when shot. Some suggested tipping the cases over when done. You need to back of the die until the body and shoulder are not touched by the die. This will depend on how big your chamber is. Some trial and error will be needed. A .308 die can sometimes be used without the expander button running the
303 button in and out to expand the neck,
The more you learn about handloading the more complex it becomes.

Thanks, I will give this a go on me next reload. Should give me enough time to build an annealer by the time ive gone through the brass ive got anyway.
Yes it most certainly gets more complex the more you read about it. That being said, overall 303 appears to be an easy cartridge to load, just need to be aware of its quirks it seems if you want to get the maximum life out of the brass.
The more rifles you use your reloads in seems to be the biggest factor here.
Been reading about the "o-ring" trick too, not sure if this is something you recommend.
Ive noticed that my brass once fired is longer than original too, but im putting this down to potential erosion in the throat of the rifle?
Im looking into what the maximum case length is to see if i need to trim it or not.

Originally Posted by Micky Duck

. Think about it.... You MAY have used case fired in a tightish/ smallish chamber,so yes it will fit in a largeish chamber....but it won't work the other way around... To partial length resize you EXPERIMENT with how much to back it out till you get it to chamber with just wee bit of resistance....but remember the SMLE is cock on closing with little camming action,too tight is faaarkin frustrating with red hind looking at you fifty yards away....

Yes thats right, I will need to test between rifles, but at a glance, so far my fired brass appears to have the same fit, it could still be out by a few microns however.

Originally Posted by Jhon

Quote: "What part of the case will fail with FL resizing? I take it that the brass splits down the side? I thought the neck would be the first place to fail, but i take it that annealing largely addresses this, can the whole case be annealed at all?" Endquote.

First never anneal past the shoulder. If you do you will tend to get unpleasant results like case length crushing when you seat bullets.

Second, if you anneal the case neck you extend the reload life of the the case and enable correct neck tension on the bullet. If the brass is too brittle and hard it not only splits but it springs back when resized so neck tension is less and not uniform case to case.

Third, the case will eventually fail if not from neck splits then two other things. If full house loads the primer pockets eventually won't hold a primer tight. Same in all cals..with 303B brass, before primer pockets fail you are likely to get case head separation. Especially if you FL.size for a generous chamber and larger headspace dimensions. To check for incipient head separation use a thin wire, folded out paper clip, with a small hook bent on one end. Insert in case head and draw forward, hook against case wall. A short distance from the head, maybe 4-5mm, you may feel the hook catch. The brass has thinned here forming an internal groove. On the outside opposite the groove you can usually discern a shiny ring. If either it is time to discard the case or risk it rupturing and separating head from body the next time you fire it. 303B brass is well known for this. Not such a problem if you are loading down and neck sizing. Primer pockets dont stretch as much either.

The cases only tend to split down the side if the brass is old, rotten or really tired and brittle. Hot loads will do this with old brass like some of the HXP and old 1940s-50s CAC etc. Young brass like factory PMC, Hornady etc likely won't give you side splits. You'll get split necks, case head separation or loose primer pockets prior. Long life for 303B comes from good brass, annealing, neck sizing and modest charges.

Yes it appears case separation is the big one here.
Will be interesting to see how i go with this HXP brass ive got.
I will probably do some experimenting to compare FL resizes vs neck size only too.
What do you call a modest charge? Where would a military load sit? Looking at load data, they still sit below the maximum load published.

Originally Posted by Old_School

Thanks, I will give this a go on me next reload. Should give me enough time to build an annealer by the time ive gone through the brass ive got anyway.
Yes it most certainly gets more complex the more you read about it. That being said, overall 303 appears to be an easy cartridge to load, just need to be aware of its quirks it seems if you want to get the maximum life out of the brass.
The more rifles you use your reloads in seems to be the biggest factor here.
Been reading about the "o-ring" trick too, not sure if this is something you recommend.
Ive noticed that my brass once fired is longer than original too, but im putting this down to potential erosion in the throat of the rifle?
Im looking into what the maximum case length is to see if i need to trim it or not.




Yes thats right, I will need to test between rifles, but at a glance, so far my fired brass appears to have the same fit, it could still be out by a few microns however.



Yes it appears case separation is the big one here.
Will be interesting to see how i go with this HXP brass ive got.
I will probably do some experimenting to compare FL resizes vs neck size only too.
What do you call a modest charge? Where would a military load sit? Looking at load data, they still sit below the maximum load published.

I tend to load mostly cast bullets in my 303B these days running under 2000fps. Getting sights sorted that are regulated for military use is an issue but my 303s are all sporterised versions..a scope sorts any sighting issues. A target ladder/aperture sight would also give you this.

Anyway, looking at ADI current data for say, 174gn, I'd personally call a "modest" charge anything in the bottom half of the listed range. For a velocity in the 2100 fps range. If you start looking for velocity around max or even above thats where I would expect to get shorter case life. Others might want to venture different views here. I've not played with lighter weight bullets in the 303B but I've read of folk using for instance, pulled 124gn 7.62x39 projectiles. I suspect you'd need a decent bore. ADI has data for a Speer 125gn bullet in the 2700-2900fps range. That's pretty crisp but probably not as hard on cases due to the lower inertia of the lighter bullet. If you used Trailboss or say an appropriate Pistol/Shotgun powder you could develop quite a low stress plinking load. I've read and saved somewhere info on folk doing this. Be aware tho that low velocity doesn't automatically mean low pressures. It's not hard to blow things up using these powders in rifle as they peak pressure very quickly. Use published data for Trailboss and for the others start at around 8gn and stay below 12.5. For subsonic work downwards from.8-10gn checking bullet leaves the barrel. Do any of this at your own risk. I use a charge of 6gn Nobel 78 Shotgun powder (equivalent to AS30N and/or Red Dot) for subsonic 189-200gn cast bullets and up to 12gn for 1600fps..Absolutely no fillers used. YMMV.

Originally Posted by Old_School

Thanks, I will give this a go on me next reload. Should give me enough time to build an annealer by the time ive gone through the brass ive got anyway.
Yes it most certainly gets more complex the more you read about it. That being said, overall 303 appears to be an easy cartridge to load, just need to be aware of its quirks it seems if you want to get the maximum life out of the brass.
The more rifles you use your reloads in seems to be the biggest factor here.
Been reading about the "o-ring" trick too, not sure if this is something you recommend.
Ive noticed that my brass once fired is longer than original too, but im putting this down to potential erosion in the throat of the rifle?
Im looking into what the maximum case length is to see if i need to trim it or not.




Yes thats right, I will need to test between rifles, but at a glance, so far my fired brass appears to have the same fit, it could still be out by a few microns however.



Yes it appears case separation is the big one here.
Will be interesting to see how i go with this HXP brass ive got.
I will probably do some experimenting to compare FL resizes vs neck size only too.
What do you call a modest charge? Where would a military load sit? Looking at load data, they still sit below the maximum load published.

The lengthening of the case is likely due to a combination of loose headspace at the rim and a roomy chamber. The stretching mostly happens a little ahead of the head and this is where it will crack if the case is FL sized repeatedly. When a .303 round is fired the case is driven forward in the chamber by a combination of the firing pin strike and the primer firing until it is stopped by the rim. Next the case body expands to fit the chamber. If the pressure is low the primer will be backed out of the case a little when extracted. If the pressure is high enough as with factory loads the front section of the case is gripping the chamber walls and stays where it is. The rear half is forced back by the pressure with the case stretching just in front of the head, eventually cracking at this point. To get decent case life pressure needs to be kept low enough to stop the stretching. A protruding primer will help in this.
GPM.