Long throat on new .280 AI “match”

[WestMOhunter]

Just getting started with load development on a new .280 AI. Trying to find lands/jam and find that a 168 ABLR at 3.330” is about .200” off lands. I don’t have enough bullet in the neck even at .040” off. Confused. The barrel is a CBI 8.5 twist chambered by Criterion. I get the “match” designation would be a longer throat, but I can’t figure out why they would make the throat so long. Seems I’ll be roughly .080 - .100 off lands with 160+ bullets, which aren’t exactly light for caliber. Thoughts?

 

[Vern400]

No, it is what it is. I've set back several barrels to get the lands closer to the bolt face. Some manufacturers like lots of freebore- guess it might help reduce pressure rise using every ammo under the sun on hot cartridges but not sure. I shoot 308 and I want my bullets 0.010 off the lands at mag length so they'll feed. In my peepopper that's 2.825 inch OAL. I'm no super expert but real long throating hasnt helped accuracy for me.

 

[49ereric]

How much bullet is in the case?

 

[WestMOhunter]

Not even the bullet diameter. I believe there was roughly .180-.190” bearing surface of bullet touching the case. Seating the bullet another .100” would get me there, but hence the .100” MINIMUM jump. That seems crazy with a bullet as long as a 168 ABLR.

 

[49ereric]

change the bullet it seems to be your only easy choice.
Is there a flat based bullet that would work?
probably not what you want to shoot though.

 

[WestMOhunter]

change the bullet it seems to be your only easy choice.
Is there a flat based bullet that would work?
probably not what you want to shoot though

 

[WestMOhunter]

Thanks, but that’s the issue. I chose that cartridge, bullet weight selection, etc. for a couple reasons. I want to shoot a higher BC target bullet at steel with moderate recoil (160s) and a bonded bullet that will perform well to 600 on elk and whitetail. A 162 ELD-M and 168 ABLR aren’t the only bullets that fit the bill for those, but that’s what I have and what I want to shoot. I suppose there’s no good answer for this dilemma, but thought I’d see if some of the top reloaders and shooters on here might have additional insight. Needless to say, I just learned a lesson on making sure I ask the right questions before ordering a barrel.

 

[Axlrod]

The first thing to do is see how it shoots.

 

[WestMOhunter]

The first thing to do is see how it shoots.

Fair enough. But seating a 162 ELD-M with the min .284 bearing surface in the case neck gives me a starting point of .100” off the lands. I’m not excited about burning up components with that as a min. starting point. A 140 AB came out similarly. Just disappointing, but at this point your suggestion is my only option that doesn’t end up with me throwing away substantial $.

 

[Harvey_NW]

Fair enough. But seating a 162 ELD-M with the min .284 bearing surface in the case neck gives me a starting point of .100” off the lands. I’m not excited about burning up components with that as a min. starting point. A 140 AB came out similarly. Just disappointing, but at this point your suggestion is my only option that doesn’t end up with me throwing away substantial $.

Try it. I have a 280ai built on a Tikka action and I'm loading the ELD-M to mag length which is somewhere around .100" jump when I roughed out a measurement, it shoots great.