280ai twist rates

[silverbullet555]

Good day,

I don't think materials are going to get any cheaper so it is time to suck it up and get going on components to build a 280ai.

Base is a new Tikka T3X LH in 6.5CM

For now, this rifle will be used for deer and probably elk though I have a 7mm rem that is for elk, at least in my head.

Anyway, I'm buying a proof carbon barrel for it.

Have a source for 1:9 prefit barrel 24" or a 1:8.34 24" blank.

The questions comes down to twist rate. The prefit would be an easier deal and probably save me a little in gunsmith charges, but I don't like to let a small overall cost difference impact my decision.

My guess is that I'll likely be shooting 162eld-x or similar projectiles most frequently, but don't want to regret down the road going with a barrel that is too slow.

So, which twist is the better choice?

I know the impact if I go too slow of a twist and want to run a heavier bullet. What's the downside of going with a faster twist rate if I want to shoot something lighter like a 150gr for antelope?

 

[Tim in Wa.]

Following.

 

[762 ULTRAMAGA]

Good day,

I don't think materials are going to get any cheaper so it is time to suck it up and get going on components to build a 280ai.

Base is a new Tikka T3X LH in 6.5CM

For now, this rifle will be used for deer and probably elk though I have a 7mm rem that is for elk, at least in my head.

Anyway, I'm buying a proof carbon barrel for it.

Have a source for 1:9 prefit barrel 24" or a 1:8.34 24" blank.

The questions comes down to twist rate. The prefit would be an easier deal and probably save me a little in gunsmith charges, but I don't like to let a small overall cost difference impact my decision.

My guess is that I'll likely be shooting 162eld-x or similar projectiles most frequently, but don't want to regret down the road going with a barrel that is too slow.

So, which twist is the better choice?

I know the impact if I go too slow of a twist and want to run a heavier bullet. What's the downside of going with a faster twist rate if I want to shoot something lighter like a 150gr for antelope?

You'll be good to go with an 8 twist, I definitely wouldn't go 9 unless you're shooting 150s and lighter.
I'm doing a similar build on a tikka right now and I'm sure you're aware of this already but the 280 ai will be handicapped in the shorter 3.3" tikka action.
I was thinking about the 280ai for my 18" barrel, but after comparing a custom throated 284 win to the saami 280ai I decided to go with the 284.
There was about a 25 fps advantage to the ai with 6 grains more powder from one source I found. Plus 284 Lapua brass is abundant now

 

[silverbullet555]

You'll be good to go with an 8 twist, I definitely wouldn't go 9 unless you're shooting 150s and lighter.
I'm doing a similar build on a tikka right now and I'm sure you're aware of this already but the 280 ai will be handicapped in the shorter 3.3" tikka action.
I was thinking about the 280ai for my 18" barrel, but after comparing a custom throated 284 win to the saami 280ai I decided to go with the 284.
There was about a 25 fps advantage to the ai with 6 grains more powder from one source I found. Plus 284 Lapua brass is abundant now

Handicapped how? Magazine length? Planning to change bottom metal.

I thought the Tikka actions were all same with different bolt stops.

I'm open to being educated.

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[Trigger06]

A 9 twist works great for me with the 162 ELD-X (Kimber Montana). But if you want to shoot heavier, go with the 8.5 or 8 twist. If I were building a custom gun, I'd go with the 8.5.

 

[Wapiti1]

1:8 is good for bullets down to 120. Even 110's will shoot, but you probably won't get the best groups. Typically, fast twist barrels will shoot light bullets fine, but you may have to reduce velocity to get good groups.
As for the mag length, the stock long mag on the Tikka is about 3.4". That is fine for a 280 with 160 weight bullets, even VLD's. If you want to go heavier, a longer mag is nice, but not required. You'll just lose 50-75fps before you hit max pressure due to the bullet taking up a little more space. You'll have to go with something like Redsnake bottom metal for AICS mags to get a longer mag.

This is why a lot of folks go to the WSM line of cartridges in the Tikka actions.

Jeremy

 

[fightthenoise]

An alternative solution is the 7 SAUM prefit from Proof. It’s an 8.4 twist and lends itself better to the Tikka action. You can seat bullets as far out as you want, while the 280 will be limited to ~3.3 OAL even with different bottom metal because longer rounds will get hung up in the ejection port when you go to unload. The ballistics and powder capacities are identical. Kenzies has a 24” in stock right now.

 

[wind gypsy]

For illustration, a 180hybrid seated with the front edge of the bearing surface at the case mouth gets you at 3.392" COAL.

No reason to get a custom barrel just to be constrained like that.

 

[CApighunter]

I built mine with an 8.4 twist proof. No complaints but I’d use an 8 twist if I did it again. If you want to shoot heavies from a Tikka the SAUM is a better option. Any good smith can open the boltface if you already have a standard action.

 

[warrbuk]

You can run an 8 twist, it will be overkill for 160 class bullets and cost you some velocity.

9 twist will stabilize 180 berger VLD’s at sea level in a magnum case.

I run a old school 10 twist and stabilize 168’s at sea level. It probably isn’t optimal stability but it it under .75 MOA

If you ever envision shooting copper mono’s get the 8 twist


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[realunlucky]

I built mine on a 8.5 twist everything is a compromise.

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[Forest]

I am in the same build. I changed my mind from a 280ai to the 7 saum. I ordered a 8 twist carbon six barrel, 20".
I switched to the saum for a couple reasons, first was mag length leaves all the options on the table (same for the 8 twist) and also the saum seems to be less affected by the short barrel.

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[Scotto]

Mine is 8.4. No complaints.

 

[Dcrafton]

Go with a 7.4, then shoot the high BC 180-195 bullets.
Mine is shooting 180 ELDM’s at 2917fps. Amazingly accurate.


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[silverbullet555]

As with everything, there are a plethora of options and opinions. I had a conversation with my gunsmith yesterday, who is good at what he does, and based on the likely use for this rifle, under 175 grain pills, I went with the 1:9. We'll see how it works out. I have a second rifle that will be built after this one, most likely in a 7 mag which I'll use to send some larger pills downrange.

I have aspirations of being a better and more active shooter than I have time for. Fortunately, we can always adjust or build more rifles.

 

[452b264]

If you plan on shooting say the 155 gr. Hammer you want a 1/8 or at the minimum 1/8.4

 

[silverbullet555]

Well, I did go and buy a second barrel as a blank. It's a 1:8.24 twist 24" blank. I'll still have it built the first time with the 1:9 as my smith recommended, but now I have a barrel that can be used to redo this one or for my upcoming 7mm mag build which will need a barrel too! Stocky's seemed to have some pretty good prices with sales so it made sense to jump on it. Hopefully some good deals on LH stocks will come up int he next 7 or 8 weeks and I can aquire the rest to build the 280 then the 7mm

 

[Unckebob]

As with everything, there are a plethora of options and opinions. I had a conversation with my gunsmith yesterday, who is good at what he does, and based on the likely use for this rifle, under 175 grain pills, I went with the 1:9. We'll see how it works out. I have a second rifle that will be built after this one, most likely in a 7 mag which I'll use to send some larger pills downrange.

I have aspirations of being a better and more active shooter than I have time for. Fortunately, we can always adjust or build more rifles.

Have you tried 175 grain bullets in yours yet? I went with 1:9 because I plan to mostly shoot 130-162 grain bullets (still trying to find the right bullet for my build. I have read the 1:9 is fine for the 175's, but probably won't test it unless I win the lottery and schedule that Africa trip I want.

 

[Darryle]

I thought there were a couple of Tikkas floating around here with the modified ejection port?

 

[letrbuck]

My AI has a 9 twist and shoots 175s really well. much heavier and velocity drops enough that it's not worth the trade off IMO