Thread: 7 x 57 0r 284W F Class open?

I have a Ruger M77 long action, currently with a 24 inch Shilen 7x57 barrel. Plenty of room to seat long projectiles. Is it suitable for F Class open?

Alternatively should I seriously consider rechambering to 284W? It's push feed, and works reliably with 284W rounds. Jams in chamber obviously.
The barrel would have to be set back a few thou and chamber reamed. Would it be worth the effort?

I load 284W for a mate so have dies and cases and plenty of suitable powder.

Your thoughts please.

Hi
I have a Brno 601 7x57 that has been reamed out to 284W, it works well and I shoot the 160 speers with it for hunting. My one will handle 2 in the mag and feed well, however if I put 3 in it doesn't feed reliably, not a problem if using for F Class. I had a Ruger M77 years ago in 7x57 and it reamed out to 280 AI and it worked great as well.

Regards
Ruger7mm

@Ruger7mm. Thanks for the feedback. I thought about 280AI too, but already set up for 284W. Good to hear no feed issues.

Originally Posted by RugerM77

I have a Ruger M77 long action, currently with a 24 inch Shilen 7x57 barrel. Plenty of room to seat long projectiles. Is it suitable for F Class open?

Alternatively should I seriously consider rechambering to 284W? It's push feed, and works reliably with 284W rounds. Jams in chamber obviously.
The barrel would have to be set back a few thou and chamber reamed. Would it be worth the effort?

I load 284W for a mate so have dies and cases and plenty of suitable powder.

Your thoughts please.

If you want to be competitive, the bullets you use along with type of stock (accommodating of a long, heavy barrel with suitable forend) will matter more than the chambering.

Personally would have a look at what is being used at the National level before jumping in with both feet. Bipods and rear bags are another component that the rifle must be designed around and not vice versa...

@RugerM77 shameless plug for our local range but we open next weekend and you could try out your rifle and talk to some F Open guys
https://www.sporty.co.nz/tepukerifleclub/Home

We have 284 shooters and 7mm Walkers, I dont know if you are already into F class shooting but I think its something you need to see whats around before investing.
How many feed in the mag wont be a consideration in F class as they are single feed (Range protocol) your limitation for further shooting will be the barrel length. Come and have a look, cant hurt.

Originally Posted by RugerM77

I have a Ruger M77 long action, currently with a 24 inch Shilen 7x57 barrel. Plenty of room to seat long projectiles. Is it suitable for F Class open?

Alternatively should I seriously consider rechambering to 284W? It's push feed, and works reliably with 284W rounds. Jams in chamber obviously.
The barrel would have to be set back a few thou and chamber reamed. Would it be worth the effort?

I load 284W for a mate so have dies and cases and plenty of suitable powder.

Your thoughts please.

Greetings @RugerM77,
You might want to check the barrel twist first. Some Ruger 7x57 rifles had 1 in 10" twists which would limit the type of projectile you could use, The .284 case is shorter so the barrel would need to be set back, perhaps quite a bit, to get a clean throat for the new chamber.
GPM.

Check twist rate. Probably either 9.5:1 or 10:1. Could you try some longer/heavier projectiles in 7x57 to get an idea of stability? Should be ok with 160-170gn, but might struggle with 180gn...

velocity-wise, should be able to get 2750 fps from 284w with 180gn loaded out to 3.4". What's the action/mag length?

You can actually get almost the same velocity with 7x57 loaded to 3.4" length if you load to the same pressure - around 63k psi. But this is higher than the max. allowed pressure of 56.5k psi.

I assume the action can handle the pressure fine, maybe someone else with better knowledge than me can provide input on case pressure. Maybe depending on brass the 7x57 can be run a bit hotter than book?

Either way, you could probably try some projectiles in 7x57mm first to see what it shoots before spending money rechambering...

@grandpamac thanks for your feedback. Yes, would have to set barrel back, hadn't considered the clean throat though. The barrel's a Shilen 1:9, shoots 162's ok. The whole question revolves around gaining extra velocity, the issue being: Is it worth the effort. Everyones feedback is very helpful. @bjp BT's engage the lands at 3.250 COAL and still feed nicely from the mag. Pressure wise, using Nosler data for the 140BT, have worked up H414 3.5 grains above max. 3 grains above shot and extracted ok, 3.5 grains showed excessive pressure with stiff extraction and loose primer pockets. No idea of the actual psi. My actual go to load for that projectile is 49.8 of 760 which shoots very nicely @2860. So, yes, it would seem action will happily handle loads above max data judiciously worked up.

At the end of the day, I think the original question has been answered.

Thanks to all.

FYI, couple of screenshots from GRT for W760 (H414) at 49.8gn and 52gn for your rifle (reduced the case capacity slightly to get 2860 fps at 49.8gn):

shows around 60k psi at 52gn. I don't suppose you chrono'd it? Anyway, thought it might be of interest...

@bjp. Very interesting, thanks. 52 grains is asking for trouble!
It's commonly held that W760 and H414 are one and the same and the load data's interchangeable.
Not so sure myself.

Appreciate the effort you've gone to with that readout. 49.8 of W760 gave me a four shot ES of 12 and groups consistenly under minute of angle, 3 shot. Pressure close to max, yet no obvious signs. I'll keep an eye on the brass.

I'll give 162's another crack I think, see how I get on.

Not quite dork of the week, but I managed to to get numerals in wrong place. It's 48.9 of 760 for 2860. Not surprised read out was a little hot.

Originally Posted by RugerM77

Not quite dork of the week, but I managed to to get numerals in wrong place. It's 48.9 of 760 for 2860. Not surprised read out was a little hot.

Changes things a bit - sticking in GRT, shows 53k psi pressure at 48.6gn, means your 52gn load would have been running at around 66k psi, velocity around 3050 fps? Not surprised you had pressure signs at 52.5gn!

Loaded to 55k pressure with 162gn eldm, same COL (can you load them longer?) you should get around 2690 fps with 46gn 760. But potential to get up to 2800 fps loading hotter (up to 60k psi). Not sure what brass life would be like though...

If you can load the heavier projectiles out a little longer, you'll do better than me with my 20" barrel 284w with 3.0" max COL...

Can possibly seat the eldm's out further, depends on the ogive, I believe they're quite long. Certainly got room left in the mag.
On my agenda to give them a try. I'll post result.
The other wrinkle relates to H414 vs W760. The jury's out with me as to whether same or not. I know Nosler don't think so.
Definitely supplied by the same people that make Win powder, but..........

Answer to the powder question might lie here... https://www.nzhuntingandshooting.co....57/index2.html

about 1/4 of the way down the page...
from @grandpamac:
W760 is a Winchester powder. H414 is W760 marketed by Hodgdon as W760 also is today. Formally the two powders had slightly different load data but today it is identical. Some early H414 may have been surplus and may not have varied a little more from lot to lot. Some of the data offered today is very old, up to 50 years.
GPM.

Had a read of the thread, thanks for that. Certainly answers my question. Cheers