Thread: 303 MK7 load data?

Im looking for load data to get the 2440fps with a 174gr projectile.
Been reading a bunch of threads out there with peoples loads, but am looking for some reliable data thats been used in the field.
I plan to use ADI 2209, Ive read a thread on a forum that suggests that 46.5 grains of ADI2209 should give you something close to this spec.
Not that i will trust anything I find on the internet, but its under the maximum loads published, however this is for boat tail projectiles, how would pressures and velocity go with flat bottom ones? (ive pulled a bunch from old CAC rounds, etc)
I do have boat tail projectiles that I plan to try out, they are hornady .312 174gr boat tail which I believe are no longer produced, but would make a good candidate for a mk8z round.

Your barrel might produce slightly more or less velocity than the next for a given charge weight. You might have a different powder lot. Cases with slightly different capacity. Different primers. Different projectile etc... So you can't just get someone to give you a charge weight and expect it to do exactly the same thing for you. Collecting "reliable data that's been used in the field" isn't the shortcut you probably think it is.

But it's no problem - if you have access to a chrono, it will only take you a few rounds to figure out what kind of charge weight you need to get you where you want to be with your chosen projectile. Start around 46.5gr if you want. See where it gets you and tweak as needed. You don't have to get it right on the first round (and you'd have to get pretty damn lucky to do so even if someone were to give you a number).

Originally Posted by Pommy

Your barrel might produce slightly more or less velocity than the next for a given charge weight. You might have a different powder lot. Cases with slightly different capacity. Different primers. Different projectile etc... So you can't just get someone to give you a charge weight and expect it to do exactly the same thing for you. Collecting "reliable data that's been used in the field" isn't the shortcut you probably think it is.

But it's no problem - if you have access to a chrono, it will only take you a few rounds to figure out what kind of charge weight you need to get you where you want to be with your chosen projectile. Start around 46.5gr if you want. See where it gets you and tweak as needed. You don't have to get it right on the first round (and you'd have to get pretty damn lucky to do so even if someone were to give you a number).

Yeah thats what ive been gathering, im not 100% sure how different primers affect pressure, but i know with shotgun loads it varied wildly between brands.
I dont have a chrono, but there is usually someone at the range during our club shoots who has one on hand.
My guess is to make a few different loads with different charge weights and put them on the chrono?
My main concern was that I cant see any published load data for 174 grain flat bottom projectiles, so dont want to make a dangerously high load by mistake.
Im not sure if flat bottom loads have a higher chamber pressure or not, but my gut feeling is that it might.
Of course, these military surplus loads will vary in accuracy moreso than something hand loaded and weighed rather than by volume, so I should get more consistant loads going by weight, it will just need to be within the average performance of a comparable military load i guess.

I'd do 5 groups. 46.5gr, +/- 0.5gr and +/- 1gr.

Wouldn't worry about the effect of the primer or the base of the bullet on pressure, as you should have heaps of headroom.

Shoot over a chrono, and you'll be able to work out what charge weight will give you 2440fps.

It's a 174 GRN projectiles...go to PAPER manual or a BOOK manual. Look up 303british find load data for 175 or 180 GRN projectiles. Select powder your using. Determine what velocity they predict for give charge weight. Load to that load weight ,see if your sight roughly correspond if using irons. Or adjust scope of using scope. And go shoot stuff. If happy with load DO NOT CHANGE it...no matter what chronograph says. Stick to it for as long as you can get components. If projectiles run out,get next nearest thing and continue as before. Job done.

Originally Posted by Pommy

I'd do 5 groups. 46.5gr, +/- 0.5gr and +/- 1gr.

Wouldn't worry about the effect of the primer or the base of the bullet on pressure, as you should have heaps of headroom.

Shoot over a chrono, and you'll be able to work out what charge weight will give you 2440fps.

Thats what I think I will end up doing, would 46.5gr be too much with a flat base?

Originally Posted by Micky Duck

It's a 174 GRN projectiles...go to PAPER manual or a BOOK manual. Look up 303british find load data for 175 or 180 GRN projectiles. Select powder your using. Determine what velocity they predict for give charge weight. Load to that load weight ,see if your sight roughly correspond if using irons. Or adjust scope of using scope. And go shoot stuff. If happy with load DO NOT CHANGE it...no matter what chronograph says. Stick to it for as long as you can get components. If projectiles run out,get next nearest thing and continue as before. Job done.

I dont have any paper manuals on hand, but had gone online on the ADI page and entered my specs, I dont see any flat bottom loads on there, but there are 2 different boat tail loads, both that are 174 grain and vary in pressure and velocity wildly, so its safe to say flat bottom will perform different.

FFS. Up until twenty years ago there were very very very few loading manuals that differentiated between projectiles on anything other than weight. Because people USED to use brains and followed instructions to start low and work up carefully. If you have done this a time or two for your rifle...you can often skip the really low start and go to level that normally works for you. Flat base or boat tail loads ARE THE SAME. Hells bells batman. Those cordite loads you pulled apart... The cords were cut to give. Length,chucked into a straight walled cases,not unlike 45/70... actually a .410 shotgun is closer/ correct size. The whole shebang then squeezed down to correct size n shape and projectiles of given weight bunged in on top... Then shipped off to be used. It's that simple. Follow the recipe inbook. If you don't have a reloading manuals. Buy one...or two...or three. Older the better as they have the how n why not just recipes.

2010 adi 5th edition.

Originally Posted by Micky Duck

FFS. Up until twenty years ago there were very very very few loading manuals that differentiated between projectiles on anything other than weight. Because people USED to use brains and followed instructions to start low and work up carefully. If you have done this a time or two for your rifle...you can often skip the really low start and go to level that normally works for you. Flat base or boat tail loads ARE THE SAME. Hells bells batman. Those cordite loads you pulled apart... The cords were cut to give. Length,chucked into a straight walled cases,not unlike 45/70... actually a .410 shotgun is closer/ correct size. The whole shebang then squeezed down to correct size n shape and projectiles of given weight bunged in on top... Then shipped off to be used. It's that simple. Follow the recipe inbook. If you don't have a reloading manuals. Buy one...or two...or three. Older the better as they have the how n why not just recipes.

Im still new to all of this, so am just being cautious, I am not familiar enough with what data is typically published. Your load data is similar to what ive got here anyway, so i think the 46.5gr load will be close enough to test and is within the published maximum limit, you will see here what i mean about the differences between projectiles.
I should be able to find a manual at our next gun show, I found almost everything i needed to start out reloading for next to nothing at the Auckland show and found an RCBS press for $50 a month or so ago.
I cant justify spending stupid money on new gear, this set of dies i got appears practically new.
Im not sure what to do with the rest of the cordite loads ive got, but they are hard on the barrel so is best to avoid using too many of them, ive been pulling out the stuff that looks the worst condition.

RN = round nose il (1) after that....explanation will probably be at beginning or end of data. The difference could be larger bearing surface,eg parralel bits are longer ,it's shorter and dumpy. A hpbt is hollow point boat tail ,so an aerodynamic shape with far less parralel bearing surface. But notice that if you dropped 2 grains below maximum (so roughly 5%) even if you used higher charge level with round nose,you wouldn't be over book maximum....

Originally Posted by Old_School

Yeah thats what ive been gathering, im not 100% sure how different primers affect pressure, but i know with shotgun loads it varied wildly between brands.
I dont have a chrono, but there is usually someone at the range during our club shoots who has one on hand.
My guess is to make a few different loads with different charge weights and put them on the chrono?
My main concern was that I cant see any published load data for 174 grain flat bottom projectiles, so dont want to make a dangerously high load by mistake.
Im not sure if flat bottom loads have a higher chamber pressure or not, but my gut feeling is that it might.
Of course, these military surplus loads will vary in accuracy moreso than something hand loaded and weighed rather than by volume, so I should get more consistant loads going by weight, it will just need to be within the average performance of a comparable military load i guess.

Honestly I think you are over thinking it. Fair enough if you want to but maybe not required. For instance, Hogdon used to publish (not sure if they do anymore) that if they did not provide data for a particular projectile, no matter whether cast or jacketed, flatbase or boat tail, you could pick data for a projectile the same weight (or very close) and use that PROVIDED you worked up carefully from the start charge. So it was up to you to determine what was safe and what worked in YOUR rifle.

If you look at the published specs of the rifle that they produced their published data from, few of us would have an exact match. Most of us seem to rush out and lop inches of factory barrels for a start and most published data seems to be for a 24in barrel. As to primers, heck, for the last few years if it fitted the hole we used it. Many of us learned that whatever the variation primer brand to primer brand existed didn't stop us putting meat on the table. Of course, the serious target guys will be much more particular and if that is you go for it. But in terms of pressure issues, it is incumbent on all of us to make the determination of what is safe in our particular rifle with whatever projectile, barrel length, bore condition etc that we have. Flat base vs boat tail might affect point of impact and stability at whatever distance hence accuracy but pressure, mmmm, dont think that is going to be a measurable concern. Just pick a likely safe starting point, being conservative as you wish, and go from there.

On another note, everything I've read or come across on 303B accuracy tends to extoll flatbase projectiles. Have fun.

Originally Posted by Jhon

Honestly I think you are over thinking it. Fair enough if you want to but maybe not required. For instance, Hogdon used to publish (not sure if they do anymore) that if they did not provide data for a particular projectile, no matter whether cast or jacketed, flatbase or boat tail, you could pick data for a projectile the same weight (or very close) and use that PROVIDED you worked up carefully from the start charge. So it was up to you to determine what was safe and what worked in YOUR rifle.

If you look at the published specs of the rifle that they produced their published data from, few of us would have an exact match. Most of us seem to rush out and lop inches of factory barrels for a start and most published data seems to be for a 24in barrel. As to primers, heck, for the last few years if it fitted the hole we used it. Many of us learned that whatever the variation primer brand to primer brand existed didn't stop us putting meat on the table. Of course, the serious target guys will be much more particular and if that is you go for it. But in terms of pressure issues, it is incumbent on all of us to make the determination of what is safe in our particular rifle with whatever projectile, barrel length, bore condition etc that we have. Flat base vs boat tail might affect point of impact and stability at whatever distance hence accuracy but pressure, mmmm, dont think that is going to be a measurable concern. Just pick a likely safe starting point, being conservative as you wish, and go from there.

On another note, everything I've read or come across on 303B accuracy tends to extoll flatbase projectiles. Have fun.

Yes I probably am being too technical, i agree. Just was not too sure as someone starting out.
So it sounds like providing my weight is correct, then the data should be fine to go with.
I dont know if i should worry too much, i should really put a bunch of these surplus rounds through the chronograph anyway, as I bet that they all vary wildly.

There seems to be a huge debate about BT ammo in the 303, but from the research ive done is that the consensus is that a good 303 barrel can handle it fine, the issues surrounding accuracy and/or damage to the barrel pertains to the cordite itself.
Cordite with boat tail would damage the barrel over time, but so does any cordite ammo, as it wears out the throat.
From what I gather Boat tail rounds are not accurate in a worn barrel, but otherwise should perform fine, and as far as any boat tail loads with cordite, they are few and far between, the MK8Z rounds had boat tail, but were all nitro powder which burns cooler and is kinder to the barrel.
I have some PPU MK8Z rounds that im yet to try, i think i will find they will perform just fine given that i have a good tight barrel on this rifle.

The theory/reason flat base are suggested for tire old 303s is simple. Some bores are so large or worn they are closer to 8mm...a soft flat bum on projectiles SHOULD squish out... obsturate?? Better than boat tail simply because it's already nearly out to edges of barrel,so the smack up its arse from powder exploding flattens it out like punting a foot ball. ... That's the theory.a soft cast projectile should do it better still.

Originally Posted by Micky Duck

The theory/reason flat base are suggested for tire old 303s is simple. Some bores are so large or worn they are closer to 8mm...a soft flat bum on projectiles SHOULD squish out... obsturate?? Better than boat tail simply because it's already nearly out to edges of barrel,so the smack up its arse from powder exploding flattens it out like punting a foot ball. ... That's the theory.a soft cast projectile should do it better still.

Yes, thats a good theory, thats also why I was concerned it may have a higher pressure because of this.
I had also heard that 2 groove barrels dont like boat tails as they dont engage what well with the rifling, but again age and wear from cordite over the years could be a factor.

Now speaking of worn barrels, ive got a couple of packs of Hornady .312 boat tail projectiles, I got them for next to nothing, but they are slightly oversize to make up for barrel wear for this very reason, I dont know if anyone here has had experience with them, but I believe they are no longer made and sought after. I might hold on to them for a little bit until i decide what to do with them. Probably a waste of time using them in a good barrel.

in theory any 174gr at 2440 fps will be close enough. most new manufacture 174gr FMJ are not mk7 spec. but they will be close enough

you'll find you will probably need to adjust your front sight