Should I go an 8 twist in a 7 mm?

[GSells]

Hi all , I’m looking at buying another Lilja 7 mm barrel . I’ve had a good run with a few of them now and the 280 ai has been exceptional after working out a few things .
Only thing is , button rifle barrels only come in full increments of 8 or 9 inch twist .

I would be more comfortable with a 8.5 and maybe I’ll buy another Bart as they have been good also .

Question? Has anyone had any problems and equally successes with a 8 twist barrel Eg bullets blowing up or wild dispersion or better wind shear bucking ability ( Eg Belmont) ?

Regards Graham.

[Tim N]

What projectiles are you planning to use?
180s have been fine in the last 4-5 9 twist barrels for me

[GSells]

What projectiles are you planning to use?
180s have been fine in the last 4-5 9 twist barrels for me

Hi Tim , just plan to use the new 184’s and I’ve used 9 twist for some time now . But also plan to use 180 hybrids and vld’s .

[Tim N]

I haven’t used the 184s so can’t comment

[John Smith]

A 9 is fine for the 184s a tighter twist will be a bit harder to tune and keep the throat at a happy clean dirty level
John

[bruce moulds]

why?
bruce.

[KHGS]

What Bruce said. 9 twist will handle any sensible to use 7mm bullet!! Unless you want to make some of the overweight bullets work......that no one else has been able to get to work ..........consistently and for what gain???? I imagine you have heard the term.....point of diminishing returns????
Keith H.

[Dicko]

Hi Graham,
I've just finished running in and load developing a 284 with a Brux 1:8 twist barrel for a bloke not sure why 8 but but fire forming loads with 180 ELDMs with 2209 shot extremely well. And 180 laps shot even better. No random flyers or exploding bullets either. I'd be pretty happy to not have to give it back!

[GSells]

Hi Graham,
I've just finished running in and load developing a 284 with a Brux 1:8 twist barrel for a bloke not sure why 8 but but fire forming loads with 180 ELDMs with 2209 shot extremely well. And 180 laps shot even better. No random flyers or exploding bullets either. I'd be pretty happy to not have to give it back!

Thanks mate , I’m not rich by any means and I really can only afford something that works . And there is nothing like first hand experience !

[GSells]

why?
bruce.

Why , just at Belmont we get a lot of up and down drafts . I’m getting an SG of 1.4 at 2950 FPS with the new copperheads 184 and slightly worse 1.38 with the Bergers 184’s . From my experience with testing the 180 eld’s at Belmont against 284’s w using hybrids. The eld suffered greatly ( 9 twist ) in the vertical in head winds . Where as the 180’s in a 9 twist seems to buck this strange annoying phenomenon.

Going back to Pinjar ( which is like NorthArm on steroids!) the flat ground did have an effect with head and tail winds but no where near the vertical experienced at Belmont.

That’s Gut feeling , a properly dynamically stabilised bullet won’t experience as much over turning motion ( if that is what it’s called ?) Or will resist vertical leverage thus creating drag or in some cases reducing drag and therefore “ Bucking the vertical!” To some extent .

On flat country like Pinjar with no huge mounds , I’m thinking, yes a 9 twist will shoot well !??
Just my thoughts?

[GSells]

What Bruce said. 9 twist will handle any sensible to use 7mm bullet!! Unless you want to make some of the overweight bullets work......that no one else has been able to get to work ..........consistently and for what gain???? I imagine you have heard the term.....point of diminishing returns????
Keith H.

I totally agree with you Keith, no one has gotten the 190 elite hunters to work properly. At Gundy in a 8 twist they blew up if that’s what was being used . But had a very high x count . Is too much of a good thing bad . At some point spinning up such a heavy bullet can cause problems.

I haven’t seen too many 8 twists out there and maybe because it’s bettet to have a bullet reach the target for a 5 or 6 than a zero ?

[bruce moulds]

why?
bruce.

Why , just at Belmont we get a lot of up and down drafts . I’m getting an SG of 1.4 at 2950 FPS with the new copperheads 184 and slightly worse 1.38 with the Bergers 184’s . From my experience with testing the 180 eld’s at Belmont against 284’s w using hybrids. The eld suffered greatly ( 9 twist ) in the vertical in head winds . Where as the 180’s in a 9 twist seems to buck this strange annoying phenomenon.

Going back to Pinjar ( which is like NorthArm on steroids!) the flat ground did have an effect with head and tail winds but no where near the vertical experienced at Belmont.

That’s Gut feeling , a properly dynamically stabilised bullet won’t experience as much over turning motion ( if that is what it’s called ?) Or will resist vertical leverage thus creating drag or in some cases reducing drag and therefore “ Bucking the vertical!” To some extent .

On flat country like Pinjar with no huge mounds , I’m thinking, yes a 9 twist will shoot well !??
Just my thoughts?

graham,
my question "why" was directed at the post immediately before.
bruce.

[GSells]

I’m obtaining about 80 184 copperheads length 1.575 to see if I can get them to shoot in a 9 twist in a 284 w at 2830 FPS and in a fast 7 at 1000 yds at Belmont. Unfortunately I am time poor and Belmont is a 3 hr drive . So testing will be limited and will this head and tail winds show up to test against.

The 180 Eld excursion was not a good experience for me and wasted a lot of time that could have been spent just shooting.
But nothing ventured, nothing gained ?


Oh , sorry Bruce . It started a real Relevant response that might generate some interesting comments.

[GSells]

Just mentioning Pinjar , brings back good memories! It’s nearly a month now and I believe it claims the toughest range in the nation . The SA boys can argue about lower light . But I don’t think there would be too many that would disagree?? I’ve never seen split mirage and took me right up to the end to realise what I was seeing lol! It humbled me ! And to those who conquered and made Pinjar their B^*tch !! I salute you well done ! I hope I can come back and have another crack !!
Sorry off topic.

[saum2]

Graham, Your thinking too much, I've tried both twists and 8.5T, I've had more success with 9T so my next 7mm will be 9T.
It will shoot all projectiles for you. What more do you need? I only came second at Belmont with a 9T so what would I know.