Build Thoughts

[lancetkenyon]

A buddy has two .280AIs.
He built a 26" for his daughter when her 28 Nosler proved to be too much gun for her. I did the load workup for the rifle. 175 Elite @ 2916fps.

He liked it so much, that he wanted to build a shorter (22"), lightweight .280AI to run suppressed for himself. I specced all the parts for him, and after it was built, tried the load recipe for his other .280AI in it. 175 Elite @ 2808fps, and fly shooting accuracy at 100 yards with zero load development.

Personally, 20-22" is as short as I would go on a .280AI. Just get a short 5-6" suppressor for it. Or, wait to screw the suppressor on until you get in the stand.

 

[ButterBean]

It is a bit of a myth that larger chamberings MUST have longer barrels to be faster the smaller capacity rounds of same caliber. Learned this from many years of building some rather extreme handcannons on the XP-100 platform.

in a 26" barrel, a 280 AI will be faster then a 7-08 obviously, but as barrel shortens, the 280 AI will always be faster. The velocity spread may narrow a bit but it will maintain a significant advantage, remember the 7-08 will also loose velocity. while the advantage in a 26" barrel may be 150 fps, in a 16" barrel it may be 100 fps but still faster.

excessive fireballs are generally a result of the powder type used more then anything and this is under your control to some degree by hand loading.

if efficency is big on your list, that being the FPS generated per grain of powder, then go smaller but a properly loaded 280 AI will solidly outperform any 7-08. As will a 7mm Rem Mag outperform any 280 AI in same length barrels when each are loaded to same pressures.

here in lies the issues. Its common to lean on the throttle a bit with smaller rounds to make them look more impressive then they are compared to the larger.

simply put, the fastest round in a full length barrel will still be the fastest in a shorter barrel, advantage may be slightly less but will still be faster.

similar debate as to a 7-08 AI being 100 fps faster then a standard 7-08. How is this possible with only a couple grains increase in powder capacity, simply put, most will run the AI to higher pressures then the standard round….
probably just ****ed a load of people off which was not my intent.

^^^^^^^^^^^^^^^^^ ShoNuff^^^^^^^^^^^^^^^^^^^^^^

 

[Fiftydriver]

My apologies!
I didn't word this correctly and surely sounds misleading!
Should have given the longer version. I'll try again.
The 7mm-08 would give more efficient performance in velocity per grain of powder burnt than would a 280ai in a 20" barrel simply due to volume and burn time...with the excess waste blowing out the muzzle in fireball fashion.

I did fire the exact same load in the 20" as was used in the 26" barrel so...yes, it was a slower burning powder while the 7mm-08 load was a faster powder and, as stated, my results were that the 280ai was still faster.
With that said, loading the 280ai with a faster burning powder in short barrel would help burn time but would still be less efficient in an 18" or 20" barrel for the volume of powder consumed.

As stated before... the short 7's outshine the 280ai in this configuration.

Be sure to check suppressor manufacturing recommendations for minimum barrel length/ caliber due to pressure.
Be aware of Tikka's magazine limitation for 280 AI OAL.

Have a good weekend guys!

Not only that but advantage in usable bore length as well. Many feel short fat case designs are more efficent, there is some truth to that, however, most never consider the increased usable bore length. Does add some velocity potential as well.

you are correct in powder selection as well. Smaller rounds do better in shorter barrels because they have much higher expansion ratios and as such can use much faster burning powder. There are several powders for the 280 AI that will maintain velocities better in shorter barrel lengths. Added bonus, they also generally will reduce that fireball as well.

 

[Roughrice]

One final comment:

Look at how many short 280 AI take off barrels are for sale compared to how many are still buying short barrels in 7 SAUM and 7 SHERMAN variants…

Not bashing 280 Ai…great cartridge!

Cheers!

 

[Fiftydriver]

One final comment:

Look at how many short 280 AI take off barrels are for sale compared to how many are still buying short barrels in 7 SAUM and 7 SHERMAN variants…

Not bashing 280 Ai…great cartridge!

Cheers!

The latest greatest mind set may have alot to do with that as well. Look at the number of 6.5 creedmores that sell compared to the 260 rem even though out of the same guns same bullet, same barrel, the 260 will add a solid 75 to 100 fps over anything the creedmore will do loaded to same pressures……. Herd mentality is interesting sometimes.. i have had dozens of customers want me to rebarrel their 260 rem rifles to creedmores until we have a discussion about it and really find out why they want to so this……. seldom because of a legit real world practical reason. Usually hear because you can seat the bullets out farther. Nope, same over all length requirements. Then they say, because the bullet is seated out of the usable powder capacity farther. True, but with bullets seated to same oal, the 260 still has significant capacity advantage And will produce higher performance. In the end it comes down to constant chatter that the creedmore is a better design…….

 

[akmtnhnt]

The latest greatest mind set may have alot to do with that as well. Look at the number of 6.5 creedmores that sell compared to the 260 rem even though out of the same guns same bullet, same barrel, the 260 will add a solid 75 to 100 fps over anything the creedmore will do loaded to same pressures……. Herd mentality is interesting sometimes.. i have had dozens of customers want me to rebarrel their 260 rem rifles to creedmores until we have a discussion about it and really find out why they want to so this……. seldom because of a legit real world practical reason. Usually hear because you can seat the bullets out farther. Nope, same over all length requirements. Then they say, because the bullet is seated out of the usable powder capacity farther. True, but with bullets seated to same oal, the 260 still has significant capacity advantage And will produce higher performance. In the end it comes down to constant chatter that the creedmore is a better design…….

A legit reason would be you can't stabilize a 140gr 264 bullet in a 1-10 twist 260.

 

[2buffalo]

A legit reason would be you can't stabilize a 140gr 264 bullet in a 1-10 twist 260.

i have had dozens of customers want me to rebarrel their 260 rem rifles to creedmores until we have a discussion about it and really find out why they want to so this……. seldom because of a legit real world practical reason.

What difference does it make if you are rebarreling? You can have whatever twist you want.

 

[Fiftydriver]

A legit reason would be you can't stabilize a 140gr 264 bullet in a 1-10 twist 260.

Standard saami twist for a 260 rem is 1-9. Dont think i have ever seen a 10 twist 260. Plus if your rebarreling and ordering a new barrel you would never order a 10 twist in 6.5…. Hell, 9 twist are not the most common anymore. I use 9 twist often because my wildcats have the ability to push the heaviest 6.5mm bullets well over what they are designed to be driven to, as such, the slightly slower twist works great and makes life a little easier on the heavy, long, lead core bullet designs.

 

[akmtnhnt]

Standard saami twist for a 260 rem is 1-9. Dont think i have ever seen a 10 twist 260. Plus if your rebarreling and ordering a new barrel you would never order a 10 twist in 6.5…. Hell, 9 twist are not the most common anymore. I use 9 twist often because my wildcats have the ability to push the heaviest 6.5mm bullets well over what they are designed to be driven to, as such, the slightly slower twist works great and makes life a little easier on the heavy, long, lead core bullet designs.

If they took your advise and kept their 260rem, then they aren't re-barreling.

 

[Fiftydriver]

If they took your advise and kept their 260rem, then they aren't re-barreling.

They all did keep their 260s as is or rebuilt and rebarreled back to 260 or 6.5-284 if appropriate for their receivers.

 

[Fiftydriver]

If they took your advise and kept their 260rem, then they aren't re-barreling.

most of these guys already had factory rifles in the 260. I have never had a customer that had one of my custom rifles come and ask me to rebarrel it to a creedmore. That is usually taken care of pre build while discussing options for what they want in the custom build. Again, have never built a 6.5 of any chamber with a 10 twist barrel. Hell, even when i build 257 calibers, i order 9 twist barrels.

 

[Montucky Roamer]

I've got a Tikka I was thinking using for a build. Wanting something very light to hunt with suppressed for stalking and climbing stand hunting in the woods. Thinking 18" 280Ai carbon barrel to shoot 140 grain hammers. Stockystocks has a 20 oz stock for Tikkas and top it with a 3-15x42 Razor. Anything I need to know about the 280ai? A friend of mine used to shoot them years ago and I remember him telling me about their being 2 different specs on reamers or something (one being allot shorter) and you had to make sure you got the right one for the dies you had??

So what is the real world use? Like what the actual shot distances you'll see? I'm just thinking most stand hunting for whitetails is a close range affair. Any shots even past 500 yards?

 

[Kimber7man]

My only 7mm experiences have been with 7mm08 and 7 SAUM, but I'm thinking that if a guy wanted a short 7mm on a long action, other than a 280AI or even a plain ole 280, seems he could go with a straight .284 and get most of what the 280AI does.

 

[akmtnhnt]

My only 7mm experiences have been with 7mm08 and 7 SAUM, but I'm thinking that if a guy wanted a short 7mm on a long action, other than a 280AI or even a plain ole 280, seems he could go with a straight .284 and get most of what the 280AI does.

284 on a long action with a long throat should be able to do a bit better than 280ai on a long action.