Barrel twist for 223AI shooting 80s or 90s

[Newbie2020]

I’m having a 223AI put into my R700 action.

Any suggestions as to twist rate?

Also, welcome any opinions about left hand gain twist for this round?

 

[stello1001]

7

 

[b6graham]

7 easy

LHGT might make sense here with the extended barrel life

But again with way less recoil will you notice

 

[Newbie2020]

Thanks @b6graham

@lowlight said the gain twist buys you flexibility to shoot both lights and heavies. If I understood him. Which isn’t a given.....

 

[spife7980]

It’s cool but if you can have one today vs one everntually I would take the one today.

 

[Newbie2020]

@spife7980 Dude....good point. Crap. I hadn’t thought of that. I’m with you—-I’d rather shoot than email @Frank Green every day for the next 6 months asking “where’s my barrel?!?!”

 

[Kiba]

I'm running a 6.8 gain twist in my newest 223AI, handles everything I've tried so far from to 50 grainers to 79gr copper monolithics.

RPM of the 50s at 3560 fps is crazy high at 377krpm, but they don't blow up. They do a hell of a number on ground squirrels though. We'll see if the 50s hold together as the barrel gets more rounds on it. My other 223AI has 3800 rounds on a 7.5 gain twist and the 50s are still very accurate and hold together at 3560fps. The 7.5 twist on that gun won't stabilize the 79gr monolithics though, they don't keyhole but terrible groups.

If I was only going to run 90s I'd probably even consider a 6.5 gain twist, but IMO the sweet spot for bullet weight in the 223AI is right about 75-80gr. If I want to sling 90s I'm picking up my 22BRA so I can send them at 3000fps with zero pressure issues along with plenty of available mag length for loading long and mag feeding.

And as mentioned above, unless you can find one on the shelf be prepared to wait 12 months minimum for a barrel direct from bartlein right now...

 

[Newbie2020]

According to Berger’s bullet stability calculator the 1:7 twist will stabilize everything up to 85.5s but not the 90s at my elevation and at low temps. I wanted to get some expert opinions.

 

[Newbie2020]

Thanks @Kiba good info
Are your gain twist barrels gaining 3/4 twist? Or more than that?

 

[Kiba]

Thanks @Kiba good info
Are your gain twist barrels gaining 3/4 twist? Or more than that?

My 7.5 twist 223AI barrel is 8.25 to 7.5, and the 6.8 twist 223AI barrel is 7.75 to 6.8.

I've ordered several gain twists from Bartlein now for multiple rifles and the gain in the twist recommendations vary by caliber and bullet you plan on shooting (or possibly based on who you get on the phone, LOL.) The 8.25-7.5 twist 223AI barrel was spec'd for the 75 Amax as the primary bullet, the 7.75-6.8 twist barrel was spec'd for both 75 ELD-M and Cutting Edge 79 monolithics. For my 300PRC they recommended a 9.0 to 8.5, my 6 Dasher has 8.25-7.5, and my 6.5 CM has an 8.75-8 twist on it. I figured out the stability factor for the bullets and velocites I planned on shooting and picked the final twist rate myself, then let Bartlein make the decision on the initial twist rate.

I've read about some wild gain twists being tried like 12 to 7 twist on a 223... but Bartlein didn't recommend anything that drastic when I called them. At least for the barrels I've purchased they always seem to end up recommending around 0.5-0.75 gain in the twist rate... but they'll make whatever you want.

 

[Newbie2020]

Thanks @Kiba

i guess I can order the gain twist and buy a 7 twist for now til the gain twist arrives

 

[Kiba]

Yep, if you want to shoot it anytime soon find something on the shelf somewhere, and if you really want a gain twist put in an order and wait a year (hopefully less, possibly more...)

My barrel order with Bartlein last year was placed in the middle of May 2020 and didn't ship until the middle of November-- and their backlog has grown substantially since then.

This thread reminds me I should probably order another 3 or 4 barrels from Bartlein so I'll have them on the shelf when I need them...

 

[Newbie2020]

That’s a good plan

 

[jrh84]

I shoot 88 ELD's and Berger 90's from my 1:7 Bartlein to 1000 all the time without issue. 6.5 might work fine, but it's not necessary.

 

[Seandradamus]

6.5 twist if you want to try 95s , if not then 7 is perfect, I shoot the 95s in my latest rendition and it pretty much mirrors my 6 dasher to 1000
I get 2785 FPS with 4895 and nothing else comes close in the wind

 

[Moose]

I have ran 75gr amax for years in 8 twist and they have worked out great.Also run 50gr vmax in 8 twist and no problem there either.

 

[Nortex]

7 twist runs 80's perfectly at 2950 from my rifle.

 

[granite wagon]

got a buddy that has a 7twist 26" 223AI .. He shoots 90SMK & 95SMK uses 8208w/90 & cfe223w/95. on target shots show him stable w/ 95smk at 1017yds. but it seems he is loosing a lil BC .

 

[Kiba]

6.5 twist if you want to try 95s , if not then 7 is perfect, I shoot the 95s in my latest rendition and it pretty much mirrors my 6 dasher to 1000
I get 2785 FPS with 4895 and nothing else comes close in the wind

What freebore is your chamber for those 95s and what's the loaded OAL?

I still prefer using my 22BRA to sling the heavy 90-95 grainers since you can get them to 3000 with reasonable pressure, but maybe I should try them in my 223AI-- although I doubt the freebore in my 223AI is long enough for them and they would eat up way too much case capacity.

One issue for me is being down at 15' above sea level, we can sometimes have -2000' DA on cool mornings. I've been screwed by that before when shooting marginal twist rate & bullet combos where they won't stabilize in the morning but then straighten up and shoot OK in the afternoon when the DA increases. After being extremely pissed off after a couple of morning-only shooting trips where my loads didn't work in those conditions I now tend to spec my twist rates to ensure stability on those negative DA mornings-- even if it means the twist is a bit faster than needed for most days and conditions.

 

[sinister]

You'll want a 6.5 if you're going as heavy or heavier than 90 grains.

The nice thing about a 6.5 is it'll do 80s, and it seems Sierra 77s really like the 6.5.

 

[Seandradamus]

What freebore is your chamber for those 95s and what's the loaded OAL?

I still prefer using my 22BRA to sling the heavy 90-95 grainers since you can get them to 3000 with reasonable pressure, but maybe I should try them in my 223AI-- although I doubt the freebore in my 223AI is long enough for them and they would eat up way too much case capacity.

One issue for me is being down at 15' above sea level, we can sometimes have -2000' DA on cool mornings. I've been screwed by that before when shooting marginal twist rate & bullet combos where they won't stabilize in the morning but then straighten up and shoot OK in the afternoon when the DA increases. After being extremely pissed off after a couple of morning-only shooting trips where my loads didn't work in those conditions I now tend to spec my twist rates to ensure stability on those negative DA mornings-- even if it means the twist is a bit faster than needed for most days and conditions.

My Freebore is .125 , which definitely puts the 95 into the case a bit but allows me to shoot 75s and 80s also. It has not been an issue though , I get plenty of speed and it shoots great at distance even though it’s well below the neck shoulder junction

 

[Thesepaperwings]

I'm going with a 7 twist at 26". I'll throat it for a-max bullets and 90s will probably be the heaviest I shoot in it.

 

[Kiba]

My Freebore is .125 , which definitely puts the 95 into the case a bit but allows me to shoot 75s and 80s also. It has not been an issue though , I get plenty of speed and it shoots great at distance even though it’s well below the neck shoulder junction

Thanks for that info. After doing some reading what others were doing with chambers for the the 90s and 95s I was guessing you had a .225"-ish throat.

I might play around with the 90s in my 223AI just for fun. They obviously won't hit the speeds of 90s out of my 22BRA, but it will be good info to have.

 

[Seandradamus]

Thanks for that info. After doing some reading what others were doing with chambers for the the 90s and 95s I was guessing you had a .225"-ish throat.

I might play around with the 90s in my 223AI just for fun. They obviously won't hit the speeds of 90s out of my 22BRA, but it will be good info to have.

Yes a .225 would be perfect for the 95s
That is the freebore I have in my 22 Dasher
Which pushes them about 3100 , absolute lazer but I prefer a slower load for PRS so I have shelved that reamer for now , but I’ve been lusting for a short barreled 22 Dasher

 

[sinister]

7.5 should be a sweet spot. I'd go Wylde chamber as opposed to shorter. A shorter free-bore (say 2.445) is good for your "Blunter" ogives (69s through 77s), but a little longer (2.450) lets you seat 75 ELD/VLD and 80-88 out a little longer, but not like a full 5.56 (at 2.500).

 

[Seandradamus]

I plan on doing 223 Ackley though

.100-.125 is ideal for 75-88s
I’d probably go 7 twist if leaning more towards 88s and 85s