I'm thinking of doing 1-9 barrel for my next 7mm rifle, talk me out of it.

[bitbythebug]

I just sold my 28 Nosler with a 1-8 twist barrel. It wouldn't shoot the 180 ELD-M's at all. They disintegrated before reaching the target. I was told they were spinning to fast and coming apart, I couldn't refute that. I am building a 7-300prc and am leaning towards the 1-9 twist for it. I did all the calculations on the Berger stability calculator, and it said the 9 twist stabilizes even the 195 Berger's. I was hoping the slower twist wouldn't disintegrate thinner skinned bullets, like the ELD-M. I love the 180's and would like to stay in that area for hunting but would like to be able to shoot the heavier Berger. I can order either barrel from Bartlein. Where am I going wrong with my thinking?

 

[ARlife4me]

as long as you DON'T shoot the 197smk's and what you want to shoot will stabilize, then go for it! i don't remember what the maximum rpm for cup-n-core is within reason (i think it's 437,000 or 347,000?). do you think the 8.4-8.75 is to fast in case of atmospheric changes?

 

[xsn10s]

My new Remington 700 with 1-8" 5R factory barrel shoots 180gr ELDM handloads just fine. My understanding that the rifling (3-4 groove barrels) plays a part in 180gr ELDM's blowing up.

 

[bitbythebug]

My new Remington 700 with 1-8" 5R factory barrel shoots 180gr ELDM handloads just fine. My understanding that the rifling (3-4 groove barrels) plays a part in 180gr ELDM's blowing up.

I never thought that a faster twist was a negative. I instinctively want the 1-8 but the 28 Nosler has me spooked. Maybe it was the rifling's. Would you get the 8 or the 9?

 

[xsn10s]

I never thought that a faster twist was a negative. I instinctively want the 1-8 but the 28 Nosler has me spooked. Maybe it was the rifling's. Would you get the 8 or the 9?

I would get a 1-8" to run 180's. Throat condition could cause the bullets to come apart in mid flight too. Which is why I chose a 7mm Rem Mag. I can load it as hot or mild as I want. And with the 180gr ELDM's I let the BC do the work. I'd speak to a good barrel marker like Frank Green of Bartlein barrels on the subject.

 

[nwmnbowhunter]

I have 26 inch 7 saum 9 twist 5r bart that shoots 180s lights out

 

[Phil Rizzo]

Shoot 180HT's! With ether twist, from SAUM to Nosler
Something about bullets that disintegrate on dragonfly turbulence that gives me the heebies.
But, I do realize they work well for plenty guys. Good luck with your choice.

 

[TopPin]

Interesting post, never ran into an issue with a 28 running 1-8, even with Eld x or Eld M. The 7-300 PRC will be definitely slower than the 28, and probably slower than a 7 rem mag. So I wouldn't for see an issue using that twist rate. If you ever plan on shooting Copper monolithic bullets I would definitely go to an 8 twist. They perform better in a faster twist. Good luck in your choice. Either direction you go it should work just fine.

 

[Left Hand Dave]

I would look at any of the mono bullets you may consider using if in the future you don't have a choice. If in the future you have to switch to monos and you choose to slow of a twist now you will have to buy a new barrel or shoot something lighter than you would like. Just a thought.

 

[doug2080]

Check out quarter minute magnums channel on YouTube. Can't remember which episode it was but he discusses this topic and proves a 9 twist in one of his 7 mags is plenty to stabilize even the largest of the .284 bullets.

 

[260shooter]

I'm collecting part's for a 7 RUM build and have a Proof CF 9 twist in hopes of avoiding the same thing with the 180 ELD-M's and Berger 180 Hybrids.

 

[Wachsmann]

I was just going to say the same about the quarter minute magnum channel. The 1/9 will work and he also stated that one of the great bench rest shooters said the slowest twist that you can stabilize a bullet with will generally be the most accurate. But here is one question if you had a 28 Nosler why didn't you just load it on the slow side of your going to a slower cartridge. I would think if the speed and the twist is killing my bullets then it's easy to slow it down and have probably a really great stable load. Just my thoughts.

 

[Country Bumpkin]

Someone check my math.

I don't know what velocity you were getting with the ELD-M's out of your 28 Nosler, but just to play games I'll assume it was 3,000 fps. If you had a 1:8 twist, we know that your bullet was spinning 12"/8" or 1.5 times in 1 foot (someone check me please). So at 1.5 revs per foot, times 3,000 fps = 4,500 rps… times 60 seconds is 270,000 rpm. Apply the same to a 1:9 twist and you get 240,000 rpm. Is an extra 30k RPM too much…?

I have no idea how fast is too fast (I googled it and it seems like none of the smart ppl are willing to put a number on it because there are too many variables).
This was some interesting reading (if this is against the rules I'll happily delete my post).

You are being redirected...

 

[MagnumManiac]

My only question is how many grooves did that 28 Nosler barrel have?
I ask because I know for a fact that there are several bullets, not just ELD-M 7mm, but 25, 26 & 8mm that won't handle 3 groove, and some Ballard style 4 groove barrels shooting really high velocities.
My original 2 224" 7" twist blanks were 3 groove, even a 223 was detonating light bullets, my 22-250AI I built would not hold anything below 85-88g together, even 69g of one manufacturer was detonating about 25 feet from the muzzle.

Back to the original question, I would go 8" twist because you have the better option of running LONG solid copper boolits and not worrying about crappy Hornady bullets coming apart…

Cheers.