8mm in F-class?

[DenisA]

I realise that the primary reason for 8mms not being a common F-class choice is that high BC target bullets haven't been developed and the product range of 8mm bullets is poor.

There is a 200gn SMK available.

The SMK's may not have the high BC of secant bullets, but by my understanding, tangent bullets trump VLD's in ease of tune and consistency due to the centre of pressure generally being closer to the centre of mass allowing better stability.

The other advantage to an 8mm I think might be barrel and brass life of heavier bullets.

I've thought that an 8mm/300 SAUM or WSM (.325WSM?) running 200gn SMK at 2800fps might be an accurate and comparatively economical combination.

I'm not saying it would be better than a 7SAUM or any other common LR cartridge. I just think that it would be interesting to see real world results of 8mm's in F-class.

Has anyone tried anything in 8mm?

[Brad Y]

Denis- the 8mm is not where its at. 270 win is where the movers and shakers will be moving. I would go that way

[AlanF]

Denis,

No, I haven't tried 8mm, or even 300 for that matter. But I think what you'll get with an 8mm WSM or similar is the disadvantages of the 300WSM only worse. I'm not for a moment saying that everything about the 300WSM is bad, but it does have a problem that to get competitive (with 7mm) ballistics in the wind, energy levels need to be so high that recoil is too high for most, and if you're on an affected range, energy limits are exceeded. So if you mainly shoot on a range that is not affected by a 3500ft-lb limit, and you enjoy a decent thump in the shoulder, go for it, otherwise probably not a good idea .

Alan

[johnk]

and you enjoy a decent thump in the shoulder, go for it, otherwise probably not a good idea

Better believe it. My first match rifle was 7½ kg wringing wet & the only pill that contrary barrel would shoot half decent was the 220 SMK. I cam back from Tassie in 2003 with neuralgia from cheek to knee & it took months to go away.

[BATattack]

Denis- the 8mm is not where its at. 270 win is where the movers and shakers will be moving. I would go that way

Don't laugh Brad! Berger have brought out a new 170gr .277 with a BC of .339!

[macguru]

I was thinking of chambering a fast twist barrel for my savage saum in 300 wsm so i could shoot any 30 cal pills i felt like, from 155 to 230 grains ...... for NSW ranges, apart from malabar, thats legal. However, as long as i can get a supply of 7mm pills i will probably stick with the saum, thats comfortable for me to shoot in a 9.5kg rifle. Notice that for 30 cal i would go with the larger wsm case.

[DenisA]

I'm pretty sure that within the next few years we can expect to see 7SAUM commonly running 195 Hybrids in Australia. I would have guessed that a bigger hole with, maybe less bearing surface area???, a similar weight bullet and a similar amount of powder (maybe less), from the same case, the recoil in the 8mm might be less.

In the distant past I have shot 230's well above 2800fps in a wsm. With the right recoil pad (I used Xcoil) the FELT recoil is very soft.
Agreed, there is a school of thought that's says the heavy recoil subjects the gun to too much interference before the bullets exits the barrel.

Range limits would definitely prohibit us from getting full value from 8mm bullets.

I think the 200gn' at 2800 would not be a hot load.

I agree with you Alan, but I'd still love to see it in reality rather than theory.

[RDavies]

Denis- the 8mm is not where its at. 270 win is where the movers and shakers will be moving. I would go that way

Don't laugh Brad! Berger have brought out a new 170gr .277 with a BC of .339!

Yes, a 270 Belmontmax (Necked down SAUM) is on the cards.
As for 8mms, I remember reading about a shooter in U.K shooting 270gn 8mm pills out of a necked up 300WSM a few years ago. I have not heard any more about it since.

[macguru]

I am sometimes shooting 195gr hybrids in my 7 saum now at 2800fps, and i am going to work the load up a little more, perhaps another 50fps. This load is legal at every range (well, its within the energy limits etc) and has about 2/3 the wind drift of the 180gr pills. The recoil is no big deal. However I concede similar velocities with the 30 cal 230gr or a hypothetical 8mm 250 gr target bullet would be unpleasant for some.... and may not achieve anything more ballistically.
Unfortunately cost and availability mean I will mainly be shooting 180-183gr projectiles. And as I said, I am considering a 30cal alternative for club shooting because it will digest a wider variety of slightly cheaper pills.

[AlanF]

...and has about 2/3 the wind drift of the 180gr pills...

Not sure how you get that Andrew. If the published BC figures are correct, then even at the same velocity the 195 calculates at only about 10-12% less wind deflection then the 180. If the 180 is run 150fps faster than the 195 (which you'd expect), then the difference is only a few %.

I have a similar situation with the 7 Shehane. At the same velocity the 180s have about 8-10% less deflection, whereas if the 168s are run 150fps faster (for similar case life) then the 180's advantage in the wind is at most about 3%.

And, in most situations, that few % advantage makes very little difference. Lets say you have a drop-off in wind speed of 2mph at 1000yd which you don't see, a 195gn at 2800fps will be in error by about 265mm, and a 180gn VLD at 2950fps will be in error by about 277mm i.e. only 12mm difference!

[Tim N]

I like the sound of the new 270BM or 270-284 ....
Which way will the herd move next???
Are there any target barrels available in 270?

[macguru]

I agree Alan, I ran them at similar speeds and on paper it should be about 10%, but it seemed like more in the field. 180s had 5min right on and i had about 3min. Still there could be other reasons, even though we were shooting at the same time. Ill do some more testing....

[KHGS]

I agree Alan, I ran them at similar speeds and on paper it should be about 10%, but it seemed like more in the field. 180s had 5min right on and i had about 3min. Still there could be other reasons, even though we were shooting at the same time. Ill do some more testing....

Andrew, have you checked your wind zero with the 195's against the wind zero of the 180's? If not, you may find an error here that may be fooling you a bit. We need to be aware that in all calibers there is a point of "diminishing returns" sometimes more is not better.
On another note, I have put a 30 cal rifle together to use up a stock of various 30 cal bullets I had on hand. I am impressed with it, early days, but it is shooting very well indeed. Not a WSM. .
Keith H.

[macguru]

Wind zero is the same. The problem is that Hornsby is the wrong range to do any wind testing... And when i am away its usually a competition so its hard to put down a few of each at the same time, but i will keep some in my ammo box for the next opportunity. The results I quoted were from Malabar, and 308s had 7-8min on, 284s 5 min, but another saum and mine were in the 3 min range. He was pushing 180s faster (guessing mid 2900s), and i was pushing 195s at low 2800s. So you can make the argument that of course you can achieve the same results by pumping up the velocity.

[jasmay]

something to note, there are a few recoil reducing devices that I have seen appearing in matches of late, seem to pass the "legality test" so, if your into a big hitter like a 300WSM perhaps budgeting for one of these maybe a big help with the thump.