Thread: 303 MK7 load data?

2 GROOVE barrels.....have two grooves so are tighter than a four or six....or to put it another way 80ish % of projectiles gets big squeeze...so they should be better,less effected by wear.

Originally Posted by Micky Duck

2 GROOVE barrels.....have two grooves so are tighter than a four or six....or to put it another way 80ish % of projectiles gets big squeeze...so they should be better,less effected by wear.

Yes they appear to wear faster because there is more surface area in contact with the bullet, but apparently the 2 groove rifling made the bullets exit in an oval shape.
Here is one of many threads about it, https://thefiringline.com/forums/sho...d.php?t=466579

Either way, I will try out boat tail at some point and see how it performs.

@ Old_School

Here's something interesting, the Load Chart from my old Lee Loader, the Whackamole. I dug it out to knock the primer out of a stray bit of HXP brass that was kicking around my bench. Decided to actually reload it as I happen to have some vintage Nobel Rifle No 2 and plenty of pulled bullets.

Notice the HUGE range of bullet weights for the same powder charge. So one sees that with a constant charge of powder, varying the projectile weight simply varies the velocity. Of course the pressure will follow but not necessarily a linear relationship.The highest pressure is going to be with the heaviest projectile. Primers are simply specified as Large Rifle. FB vs BT is not a consideration

I did weigh the powder I picked up with the scoop. A level.scoop was .8 of a grain light. A mounded scoop, super full, was .2 light.

I started reloading several decades ago in my early 20s with a Lee Loader, tub of 3031 IIRC and a bucketful of fear and nervous trepidation lol. Very pleasant to go back to.

i have a no4mk1*1943 longbranch (canada) .303 and its ideal load is 180 gn flat base -being 2 land/ groove . tried 150gn ammo sprayed like a amd womens shit . 180gn sweet as and it certainly stops anything fired at .guncity did reload for me using w760 powder years ago ,but the old girl is rarely out of the safe these days .

Winchester760 is on charts as very close to 2209. What's interesting about that list John has shown,is that quite a few of those powders are still available.

Originally Posted by Old_School

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.

The Hornady 3130G .312 BT is an excellent projectile for a loose 303 barrel. I wore out a barrel with these, putting well over 1,000 through it. However, once the throat is worn a flat base will shoot better, even though most are only .3105 - .311".

I now have a new Criterion barrel which is too tight to run the .312, so I will probably move to the Sierra match king. I might have some spare Hornady .312" that I could move on.

Originally Posted by Crusty

The Hornady 3130G .312 BT is an excellent projectile for a loose 303 barrel. I wore out a barrel with these, putting well over 1,000 through it. However, once the throat is worn a flat base will shoot better, even though most are only .3105 - .311".

I now have a new Criterion barrel which is too tight to run the .312, so I will probably move to the Sierra match king. I might have some spare Hornady .312" that I could move on.

Yes please, pm coming

174 mk v11 projectiles are long for weight due to their having a fibre or aluminium tip inside the jacket. You will find that modern cup and core bullets of similar weight are shorter so don't get worried about bearing area at all.

Greetings @Old_School and all,
First thing, do not fire the MkVII ammo. The primers are both corrosive and wreck the cases with the first shot. Not that you are likely to reload it with its odd size Berdan primer. Barrels need to be cleaned with boiling water the day of shooting to prevent the damage. Additionally the cordite is very erosive, the reason many .303 rifles have severely eroded throats.
.303 data is all over the place. My rifle with a new two groove 25 inch barrel approaches the Hodgdon/ADI data but other more used rifles can fall 150 fps or more short. The Hodgdon/ADI data is for an earlier and slower version of the powder so max loads need to be cautiously approached.
But wait there is more. If cases are full length resized with the die down hard on the shell holder their life will be short with cracking showing just above the base as early as the third load.
If all this sounds like doom and gloom it is not meant to but the .303 is a cartridge with some unique challenges that need to be considered. Keeping pressures low and neck sizing will get over most of the problems. I started handloading with a .303 around 1970 and ran into problem after problem. After a while I spat the dummy, sold my .303 rifles and bought my first .308. Now 50 years later I am happily loading for 2 .303 rifles with no problems. Please ask questions if you wish.
Regards Grandpamac.

Ask csmithy. He was weaned on this calibre.

Originally Posted by TeRei

Ask csmithy. He was weaned on this calibre.

Haha yeah no. I'd be lucky if I've shot 2 packets of 303 in 40 odd years.
Put more through my 416

Originally Posted by Old_School

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.

Attachment 279554

Greetings,
At first it may appear that the RN projectile is developing more pressure than the BT. In an earlier post I mentioned that the speed of AR2209 had increased and this is a good example of that. The 46.9 grain load should be regarded as max for both projectiles.
GPM.

Originally Posted by grandpamac

Greetings,
At first it may appear that the RN projectile is developing more pressure than the BT. In an earlier post I mentioned that the speed of AR2209 had increased and this is a good example of that. The 46.9 grain load should be regarded as max for both projectiles.
GPM.

Thanks, I hope to do some reloads before I take it to the club shoot, hopefully there will be a chronograph there and then I can report back to share for anyone else who wants some reliable data.

@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?

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