7MM FO - 6.5 x 284 or 6.5 x 47?

[RAVEN]

No22 RDavies your dinners ready

[Hangfire]

We have already prepared a membership form and only need your signature and bank account details for more info!

CTV always on the hunt for a good trigger puller

[Hangfire]

the s.africans beat the americans with the 7mm tombi.
this cartridge is as i understand it a version of the improved 7x57, but i do not know finer details.
they used 168 bergers, and won in part by having better verticle than the yanks.
this cartridge would be lovely to shoot, and have excellent barrel life.
bruce moulds.

Correction: .280AI 2nd most underated cartridge on the planet!

Note to Matt: Just ask Bruce.

Just watch out he doesn't talk you into buying a Stolle!

[RDavies]

OK, I should have said, if you want to shoot the 175-180gn bullets which 95% of shooters want to do, then 2950 fps WILL be pushing pressures in MOST barrels. 162s or 168s will let you shoot 2950 fps easily. I know a lot of shooters DO get 2950 fps out of their Shehanes, but if you enter it in Quickload, the pressure will be in the red.

I like the 168s though.

[bruce moulds]

the tombi is not underrated in south africa!
bruce.

[bruce moulds]

rod,
i read your comments re pressure with great interest.
we have been seeing where people claim working speeds above 2900 with the 284 win. in fact it has become de rigeur in certain circles to require these speeds for 180/175 class bullets, whatever the case used.
and guess what? you can get these speeds from the 284, and a bit easier from the shehane version..
real world experience suggests that caselife reducing pressures are required to achieve those speeds.
in fact m l mcpherson (editor of cartridges of the world) developed a whole series of wildcats based on the 284 case improved similarly to the shehane, and found that they could give about 50 fps more than the std case in any calibre at the same tested pressure. so why be gouged for the extra price of shehane dies.
if you really want to run at 2950 - 3050 you have to go for a bigger case as you suggest. of these cases, the 280 ackley has the most to offer in my opinion, and that is among other things because it is not the other derigeur thing of the moment, short and fat.
bruce moulds.

[AlanF]

My attitude to the Shehane is this - I already have the dies and a reamer, so will make the most of them. I can run 168VLDs at 2950fps with no pressure problems, and presumably at less pressure than a standard 284. I can run 180s at 2950fps if the occasion warrants it, but may only get 2 or 3 firings from the brass. So the strategy is, use 168s at 2950 as the mainstay (still better ballistics than 6.5-284), or 180s if I can find a good node less than 2880, then if I come up against switchy conditions at the longs in a big shoot, I can have a few 2950 180s ready to pull out of the bag . Desperate situations require desperate measures I've actually found an accuracy node at that velocity, which makes it frustrating that it can't be the standard load because of the brass problems. However, even at 2800-2850, the 180s have excellent wind drift resistance.

Alan

[RAVEN]

Good to see ya starting to catch up with things there AL

[AlanF]

Good to see ya starting to catch up with things there AL

Talking about catching up with things, are you aware that BRT has a new shipment of Bergers?

[IanP]

Bruce, you are almost right! In everything we do there is not just one single rule that applies to all circumstances.

I have found that using 2213SC with 180gr Berger's in my particular Shehane chamber (see I'm qualifying this statement) I can easily achieve 2980fps. Then there is barrel length which is another factor that directly affects velocity. The thing is, that at those velocities the cases undergo considerable head expansion. I found the ceiling for 180gr bullets to be 2900 fps or less with that powder.

I also have a few pounds of RL17 and with this powder the 180gr bullets can be launched at 2950 fps without head expansion of the cases. Talking with John (Shobby) he tells me that he has achieved 3000 fps in his straight 284W with RL17 without the cases suffering.

I have learned a great deal about pressure by pushing the limits of 2213SC with the 180gr bullets. Its a great powder for accuracy but the pressure curve is a bit too abrupt to get the best velocities. You keep telling me that your shooting the 180s at 2700fps and managing to win competitions so as we all know velocity is not the only consideration to be taken into account.

It cost me 100 cases to experiment and the embarrassment of my rifle jamming thru blowing a primer out. The end result is that accuracy has not diminished thru lower velocities even out to 1000 yards!

IanP

[IanP]

My attitude to the Shehane is this - I already have the dies and a reamer, so will make the most of them. I can run 168VLDs at 2950fps with no pressure problems, and presumably at less pressure than a standard 284. I can run 180s at 2950fps if the occasion warrants it, but may only get 2 or 3 firings from the brass. So the strategy is, use 168s at 2950 as the mainstay (still better ballistics than 6.5-284), or 180s if I can find a good node less than 2880, then if I come up against switchy conditions at the longs in a big shoot, I can have a few 2950 180s ready to pull out of the bag . Desperate situations require desperate measures I've actually found an accuracy node at that velocity, which makes it frustrating that it can't be the standard load because of the brass problems. However, even at 2800-2850, the 180s have excellent wind drift resistance.

Alan

Alan, Have you tried RL17? I think the Shehane is worth the effort as it affords a bit more boiler room to play around with in the chamber. The most frustrating thing I have found is that the lapua brass seems perfect in all dimensions when fired at high (2980fps) with 2213SC except the case head. As Bruce said its a magnum case with a 308W head so there are limitations.

I'm now shooting with 1.5 gr less powder than my fave 2950fps load and it still shoots the nuts off a gnatt at 1000 yards.

Ian

Ian

[AlanF]

...Have you tried RL17? ...

I haven't rushed out to do it because I've never read about anyone getting good accuracy with it (prior to this). All the reports have been about great velocities at moderate pressures, but they all seem to go back to other powders to get accuracy.

I will try it.

Alan

[RDavies]

So, ballistic nonsense aside, you CAN easily get 2950 fps out of a Shehane, you just get case head expansion, loose primers, or have to use 168gn bullets or RL17 powder.

So if someone was starting from scratch, with no dies, cases, reamers or anything. What 7mm cartridge would the S.A shooters recommend for the windy conditions in the S.A ranges with a 308 bolt face? Are there any other European cases out there which are not yet fashionable, but could be formed into a big capacity 7mm?

[IanP]

So, ballistic nonsense aside, you CAN easily get 2950 fps out of a Shehane, you just get case head expansion, loose primers, or have to use 168gn bullets or RL17 powder.

So if someone was starting from scratch, with no dies, cases, reamers or anything. What 7mm cartridge would the S.A shooters recommend for the windy conditions in the S.A ranges with a 308 bolt face? Are there any other European cases out there which are not yet fashionable, but could be formed into a big capacity 7mm?

If I was starting from scratch for the best 7mm I would look at the Remington SAUM. As we all know there is give and take in all things and while the RSAUM gives great ballistic efficiency with 180gr bullets it does have more recoil.

I have come around to thinking that the 284 Shehane is pretty darn good and that running it at 2900fps or less is not really that much of a disadvantage. I love pushing things until they reach their limits and the Shehane shoots great at 2900fps with 2213SC powder and also at 2950+ fps with RL17, (without case head expansion).

It worries me a bit that I'm actually starting to agree with some of your comments, at least the ones that make ballistic sense

IanP

[Ovenpaa]

I shoot 7mm SAUM with 180 Berger's and I am quite happy with it, anything that puts a 180 grain bullet down range at around 3000fps is going to have noticeable recoil, at least it takes my mind off the cost every time I pull the trigger.