7mm/303 loading help wanted.

[350velocette]

Anybody here load for the 7mm/303 EPPS ?
Have a new to me secondhand flat spring High Wall complete with RCBS dies
Cannot find anybody on the web so far who can make it easy for me.
Have all the usual listed loads for the 25, 6mm and 270/303 but nothing for a 7mm
Over forty years ago used to have a full length 22/303 and a 6mm blown out case 303 all on High Walls.
Only bought this rifle because it was a quality custom job and very cheap.
Regards.

[Oldbloke]

Have you considered emailing ADI?

Or look for 303 load data with same/close bullet weight. It would be a starting point. If you use 2206H you could safely lower the charge further below the starting load as well.

[marksman]

l've had a look at quickload for this case but no luck
it does have the 303 EPPS @63gr of H20 and the the 303 british @56gr of H20

if l were you l would be looking at the 303/270 load data and trying that at same bullet weights eg.. 150gr, work it up slowly looking for pressure
obviously with the epps you will be able to go further because of the bigger internal volume, l would suggest a good jump to the lands while testing
http://www.adi-powders.com.au/rifle/270-303/

Oldblokes advice isn't bad as well

[Oldbloke]

Marksman, you just beat me with the 270-303 data. Lol. D ata will be more common

[350velocette]

Yes tried ADI but no luck.

[Oldbloke]

Yes tried ADI but no luck.

Did they reply? Or are you still waiting?

Sometimes they are slow, say a week.

[350velocette]

No they replied straight away that they could not help me.

[Oldbloke]

Hi,
Not a heap of experience here. This is an "improved" cartridge. So this is what I would do as a last resort Assuming rifle is in good condition and strong action.

270/303 load data using AR2206H is listed in the 9th ed of the ADI manual. I think you could possibly use the minimum load listed less 5% or 10% using AR2206H (only) and same bullet weight. Work up slowly looking for pressure signs. I would also ensure there is at least 20 thou bullet jump to the lands.

I could well be howled down because translating/guestimating loads like this can be risky & doesnt always work out. But using AR2206H should help mitigate the risk. Double check everything before loading and testing.

I have done this once or twice. But first shot was fired remotely. (String & tree) lol Sounds silly but I think smart.

You can reduce loads of 2206h down to 60% of the max recomended load. Do not attempt with other powders.

Reduced loads 60% max 2206H.JPG (72.59 KiB) Viewed 4380 times

Reduced loads 75% of Case capacity.JPG (39.94 KiB) Viewed 4380 times

[350velocette]

Hi Oldbloke.
thanks for your advice, I was going to do a ten percent less start load with AR 2209 and a 160 gain bullet formulated from all the loads that I have looked at such as 7x57 and 30-40 Krag as well as the 270/303 to name but a few.
Will now take your advice and look at AR2206H and a lighter weight bullet.
Took the heavy scope the rifle came with off and put on a lightweight Vintage Lyman 6 power and it still comes out at 9½ pounds on my bathroom scales. Too heavy for me to carry all day.
No you are not the only one to tie a rifle down to test a load, as years ago I had a 350 Rigby Magnum, made cases for it from 375 H/H, had the belt turned off by a friend, held the butt with an outstretched hand and pulled the trigger with a piece of bent fencing wire.

[Oldbloke]

"turned off by a friend, held the butt with an outstretched hand and pulled the trigger with a piece of bent fencing wire"


IMO too close
5-10 yards and cover/tree between you/observers and rifle

To perhaps state the obvious. There is some risk associated with developing loads in this way, so care must be taken. But firearms are designed and made with large safety margins.

[350velocette]

Hi Oldbloke,
had a look at the various ADI books I have from the 9th edition back to 1996 and the loads listed there are for AR2206 and not AR2206H.
I wrote again to ADI and asked them if they had any loads for a 7X57 improved Mauser case, as this appears to be a spitting image of the 7mm/303 EPPS
They wrote back saying they couldn't help but included a chart showing what their ADI powders are under the Hodgdon brand name which I found usefull.
Will take your advice and start off with AR2206H as I have some on the shelf and thanks again for the trouble you have taken.

[Stoney]

ADI won't generally comment on a wildcat such as you have mate. The problem lies not with the wildcat that you have but the dimensions of the chamber and also the strength of the firearm that it is chambered in. .303 cases were never intended to be reloaded and as such have a very weak area around the head of the case. Couple that with an oversize chamber or weak action...………. Just load it with 30grns AR2206H and work it up.

[bigpete]

Have you considered emailing ADI?

Or look for 303 load data with same/close bullet weight. It would be a starting point. If you use 2206H you could safely lower the charge further below the starting load as well.

They're utterly useless.

[Oldbloke]

Have you considered emailing ADI?

Or look for 303 load data with same/close bullet weight. It would be a starting point. If you use 2206H you could safely lower the charge further below the starting load as well.

They're utterly useless.

Perhaps not fair. But they are very "risk adverse". Very common in the "explosives" industry. They probably wont advise on loads without testing.

[bigpete]

Nah,they're useless.
I emailed them about a triple ball 45/70 load which I'd gotten from them originally but lost,got told they had no data for it,then I found it again and emailed them back the screenshot of the data that they originally sent me for which they'd just finished telling me they never had! Therefore,pretty useless !

[Oldbloke]

Thats disappointing

[350velocette]

A year later and I have been trying AR2206H and AR2208 and different weight bullets from 130 up to 170 grains.
Started with 33 Grains and up to 39.5 grains of AR2206H with a 160 grain Norma boat tail and 20 thou off the lands. All shot ok and no signs of pressure.
Didn't do much with AR2208 started at 35 grains up tp 36.5 grains with the same 160 grain bullet. The first load 0f 35 grain went into a one inch group and every half grain extra opened ups the group a little.
The same applied using AR2206H and the same bullet.
This was using the blown out case and also while fire forming the cases. No cases lost while fire forming.
Started at 34 grains AR2206H and ARAR2208 and up to 35 grains with a 170 lead tip flat base Sierra bullet. Good accuracy but ran out of AR2208 powder and didn't buy anymore and carried on with AR2206H with odds and ends of bullets to use them up.
The following were all loaded with AR2206H
38.5 grains and a 130 bullet open tip boat tail.
38 grains and a 140 grain bullet boat tail lead tip.
38 and 38.5 grains150 grain bulletLead tip flat base.
All using Federal primers and approx 20 thou off the lands.
All loads were shot in my flat spring High Wall.
My thanks again to all who took the trouble to post here and posting my very incomplete loads with more testing to be done for anybody with a 7mm/303 EPPS

[ZaineB]

as others have said the 270-303 data is probably the closest match, one being .284 and the other being .277 I wouldn't bother using 30cal data.

never mind just saw the date of it and realized OP replied, good to see you had some success!

[Oldbloke]

That's an old thread. Great that you come back with the results.

Well done