280AI Questions

VikingsGuy

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Working on spec'ing a custom 280AI. I hand load, but have not yet loaded for a 280AI. Two questions - How long do I need the magazine port and ejection port openings in receiver be to allow for loading long for caliber bullets out close to the lands? What is the best twist rate for a 24" barrel in 280AI for range of bullets from 120 grain to 180 grain. Gun will be primarily used for hunting.
 

brockel

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Can throat it however you’d like to reach the lands if you are having it custom built. Pick the bullet you want and make a dummy round. If you are thinking Bergers as a “long for caliber” bullet yes OAL they are long but their bearing surface is rather short so you’d end up with a shorter throat than say if you were picking a 160 grain accubond to reach the lands. I’d go 1-8” twist
 

JLS

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What bullet are you wanting to shoot? If you're going copper, I'd think something in the 145-155 grain realm would be ideal. You'd have plenty of weight, but yet still be fast enough for reliable expansion to 500 yards.
 

VikingsGuy

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First round I would try to make would be hunting round with 140 grain TTSX, 145 grain LRX or 150 grain TTSX - whichever shot better. My second round would be a 168 Berger VLD for targets or maybe the 180 grain Berger Hybrid. Third would be a 110 or 120 grain screamer for coyotes and antelope, bullet tbd,
 

brockel

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If you’d like I can make you up a dummy round with a 168 berger and a 140ttsx and get some measurements for you on how I’d probably throat it
 

JLS

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First round I would try to make would be hunting round with 140 grain TTSX, 145 grain LRX or 150 grain TTSX - whichever shot better. My second round would be a 168 Berger VLD for targets or maybe the 180 grain Berger Hybrid. Third would be a 110 or 120 grain screamer for coyotes and antelope, bullet tbd,
If you want to shoot the 150 TTSX I'd go a 1 in 8" twist. That said, I'm not entirely sure you gain a lot in doing so. It seems like the 140ish grain monos are really the sweet spot for the 280/280 AI.
 

klampson

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I have a 280 AI built on a Rem 700 action with a Benchmark #4 1-9 twist barrel finished at 24". I had the rifle built with 140-160 gr pills in mind. No problem getting 150 gr TTSX bullets to stabilize, and they are very accurate in that rifle. I've also found great accuracy with 160 gr Partitions, and have taken antelope, deer, and elk with this combo. I have a lot of faith in that bullet.
 

brockel

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I’d also look into hammer bullets. Easiest bullet I’ve found to work a load up with
 

std7mag

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Wait.... I'm confused....
You want to shoot "long for caliber bullets", then you state "120 to 180gr"?

A 180gr and heavier would be long for caliber.
168gr Berger and under, not so much.

If you want throat specific, you need to pick a bullet, and the weight, and have the throat done to that bullet/weight. And that's what you shoot.

The TTSX, and Berger VLD like to be started at different distances from the lands.
Monolith bullets typically 0.050".
Berger VLD in MY rifles like to be 0.005" off the lands. Have heard of them as far as 0.095" off the lands, but haven't seen anyone yet that has them that far off.
 

VikingsGuy

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Wait.... I'm confused....
You want to shoot "long for caliber bullets", then you state "120 to 180gr"?

A 180gr and heavier would be long for caliber.
168gr Berger and under, not so much.

If you want throat specific, you need to pick a bullet, and the weight, and have the throat done to that bullet/weight. And that's what you shoot.

The TTSX, and Berger VLD like to be started at different distances from the lands.
Monolith bullets typically 0.050".
Berger VLD in MY rifles like to be 0.005" off the lands. Have heard of them as far as 0.095" off the lands, but haven't seen anyone yet that has them that far off.
I will not be doing throat specific barrel as I plan to shoot several bullets out of the gun as mentioned. My dimension question was not about how far off lands - I feel comfortable with that, already do several guns with TTSX at 0.050" to 0.065: and scencar Ls at 0.0005". I was trying to get two pieces of info: (1) a general sense of COAL for the bullets I referenced - I say general, as I know until I find my particular distance to lands it is not final, but some general guidance as I choose between DBM or BDL and various actions [THANKS brockel] ; and (2) what best twist for this range of bullets/weights - My reading seems to say 1:9 will be good for this range, a few suggest 1:8.5 and one person above suggested 1:8.
 

Mthuntr

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In one of my 280ai posts, Steve with Hammer Bullets said that 1:9 should work with the 155's but he said they didn't really have an advantage over the 143s until 700 yards. I ordered 150 of the 143s and I'm excited to see these first hand. Just in a trend of 1 (take some major grains of salt), Hornady 280ai brass I got isn't worth the hassle so far. I have a message into Hornady about major issues with their QC on this particular lot. I bet I'll be fireforming brass after this despite my fears of a TSA agent not allowing mismatched headstamps.

You could get 140 & 150grain E-tips for real cheap from Shooters Pro Shop and I've had great luck with them in my 7mm-08.
 

VikingsGuy

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In one of my 280ai posts, Steve with Hammer Bullets said that 1:9 should work with the 155's but he said they didn't really have an advantage over the 143s until 700 yards. I ordered 150 of the 143s and I'm excited to see these first hand. Just in a trend of 1 (take some major grains of salt), Hornady 280ai brass I got isn't worth the hassle so far. I have a message into Hornady about major issues with their QC on this particular lot. I bet I'll be fireforming brass after this despite my fears of a TSA agent not allowing mismatched headstamps.

You could get 140 & 150grain E-tips for real cheap from Shooters Pro Shop and I've had great luck with them in my 7mm-08.
I was planning on using Nosler 280AI, I have had decent luck with their brass for my other guns.
 
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