284 family

[Matt P]

Hi All
Could some of you jump on the 7mm band wagon so we can all see if it has an advantage over the 6mm or 6.5, I'm sick of being the guinea pig. I don't think the big 30 cal is feasible for FC, the only one I have seen shot was a WSM and it looked like it was kicking the shit out of him for no real advantage. The 7mm maybe the way to go but for me it still needs to score more runs. The 6.5 when it shoots is great but I find it a tempremental SOB and once my current barrels are worn out I don't plan on replacing them with anymore 6.5's and will probably go back to a 6mm of some sort. As has been mentioned before BC isn't everything you still need to get them to shoot small groups and IMO the 6mm wins, and at the end of the day none of them can read wind.

Matt P

[AlanF]

Matt,

I won't be volunteering for a 7mm because the recoil will be too much for "free recoil" shooting which is what I do, and don't intend to change. Without taking anything away from your undoubted wind-reading skills, I don't think you'd be wise to go 6mm only - in rough conditions at the longs, the higher BC of 6.5mm and above will usually more than compensate for a little less accuracy. To test the theory, why don't you try going all 6BR in the Vic Queens leadup, or even better the Queens! I'm sure everyone else would like you to do that too !

Alan

[Matt P]

Alan
I didn't say which 6mm . It might be a 6 x 284 with 115gr Dtac's at 3250fps which would blow all the before mentioned calibers away. Won't be there for the lead up but hopefully I will be there for the Queens.

Matt P

[AlanF]

Matt,

Sounds like you and Jeff Cochran have similar ideas. However, as with everything there is a drawback - its all very well to be prepared to pay for a short barrel life, but the number of shots you need to develop a good load doesn't reduce, and you could end up with only a few hundred rounds of "nett" barrel life, before you have to start on development for the next one. In my opinion, your current situation with 6BR and 6.5x57AI is close to as good as it gets from what is available.

I'll be at Bendigo for the lead-up this year - need some practice in those fickle winds. Hope you can make it to the Queens.

Alan

[RDavies]

I,m pretty sure I will jump on the 7mm/284 bandwagon when my present barrel wears out. Some time through the middle of the year I will get the 284 barrel made up for the long ranges and use my smaller 22 and 6mms for the shorter ranges or low wind.

[bruce moulds]

hi,
allthis talk about the 7mm/284 reeminds me of a new cartridge i heard about the other day; the 260/6mm.
obviously the ackerly improved versions would have more to offer, but as parker. o. ackerly would have questioned, would they be overbore?

[Tony Z]

edited 5/4/06
Tony Z.

[bruce moulds]

tony,
please discuss twist rates in relation to 7mm.
i have kept 168 sierras & old 162 amaxes stable out of a1/10 twist out to 800m, albeit from a 7stw at just over 3000. this was close to sea level in summer.
bruce.

[Tony Z]

edited 5/4/06
Tony Z.

[Matt P]

Tony
What say maybe right but I have also seen a 9" twist 6mm rem that wouldn't put 2 shots together once it got past 600m. What is the formular for working out RPM and how quickly does it slow down. Maybe the bullet makers should be telling us how many RPM a particular bullet needs to spin to stabilize rather than a twist rate, is that correct or have I completely mis-understood you ???

Matt P

[RDavies]

So Tony ,are you saying it is the rotation speed causing the problems? You said 8" twist in the 6BR is OK, but not others ,I take it that this is because the 6BR is not pushing the bulets too fast ,but a faster caliber needs a slower speed to keep the rotation speed down. Or would still prefer a slower twist barrel in the 6BR and use lighter bullets across the course than an 8" twist/107gn combo? I,m interested in the BRs for the shorts.
What do you have to say about flat base bullets VS VLD bullets of the same weight in various wind conditions/ ranges?

[Tony Z]

edited 5/4/06
Tony Z.

[bruce moulds]

guaranteed twist rate in barrel?
atmospheric pressure?
berger recommends 1/9 twist for their 180 gn 7mm bullet.
this could be a good compromise twist in 7mm for 160 to 180 gn match bullets.
the 168 sierra only seems to have a bc about as good as the 155 palma 30cal sadly.
any comments?
bruce.

[Tony Z]

edited 5/4/06
Tony Z.

[John T]

TONY,
There is an annonomous poem call

RUM AND WATER

which has a line

your knowledge of the subject seems extensive and profound

Have a Bundy and Coke on me.

My first and only FO barrel is a Shilen .284, 8-grove, 1:9, 26" Light Varmit.
I bought it years ago for 300m. At the time two very good 300m shooters had been busting their bums to get their 7-08's working, using 168SMK's in 1:10 barrells that just would not hunt. They gave up on the 7-08 (one of them still shoots for OZ with a 6BR) saying the bullet/case combo was too difficult to tinker. My thought was it needed a faster twist, thus the 1:9. I think my guess was correct.

Though a novice, I had some success at the longs at 2 Queen's in 2005, using 284WIN with 168 and 180 Bergers. These bullets are sooooo long.

It is my understanding that BC/ bullet-length/twist/velocity/stability/accuracy are inter-connected, a ballanced package. Accuracy is the objective, the end product, but what is the progressive order of the components?

Obviously there can be no accuracy without stability. If there was some constant between them, life, as for 1/200 bench, would be soooo simple.

But for FO, potentially demanding an impossible 10-shot 0.5MOA GROUP from 300 to 1000, what is your order of selection of the remaining components and what would be your ideal combination (assuming 8.5flbs recoil in a 10kg rifle) ?



VBR
JT.