Nosler .280 A.I. Brass

[elkaholic]

Hi guys.....I got a bit of a surprise today when I measured the factory .280 A.I. brass. It only measured 2.521". I know when you fireform regular .280 brass that is about what you end up with but I thought the new stuff was supposed to measure around 2.540 like the .280 Rem. This doesn't make a whole lot of sense to me as the chamber spec is 2.560" Somebody help me out here. thanks.........Rich

 

[J E Custom]

Hi guys.....I got a bit of a surprise today when I measured the factory .280 A.I. brass. It only measured 2.521". I know when you fireform regular .280 brass that is about what you end up with but I thought the new stuff was supposed to measure around 2.540 like the .280 Rem. This doesn't make a whole lot of sense to me as the chamber spec is 2.560" Somebody help me out here. thanks.........Rich

Rich.
I think the chamber spec for the 280 is 2.540 and the chamber spec for the AI is 2.525 to
the neck to shoulder junction.

I haven't seen the 2.560 chamber.

Normally when fire forming the 280 to the 280 AI the neck shorten,s a few thousandths from
blowing the shoulder out So factory ammo is .010 to .015 shorter in the neck.

The chamber should be set up to shoot factory 280 loads and head space with the 280 gauge.

Factory ammo is always under sized to fit any chamber within reason and the AI dies are not
small based dies and so if you compair the fire formed brass aganst the SAAME spects, that will
tell you if the chamber is SAMME spect.

J E CUSTOM

 

[elkaholic]

Rich.
I think the chamber spec for the 280 is 2.540 and the chamber spec for the AI is 2.525 to
the neck to shoulder junction.

I haven't seen the 2.560 chamber.

Normally when fire forming the 280 to the 280 AI the neck shorten,s a few thousandths from
blowing the shoulder out So factory ammo is .010 to .015 shorter in the neck.

The chamber should be set up to shoot factory 280 loads and head space with the 280 gauge.

Factory ammo is always under sized to fit any chamber within reason and the AI dies are not
small based dies and so if you compair the fire formed brass aganst the SAAME spects, that will
tell you if the chamber is SAMME spect.

J E CUSTOM

OK, I think I've figured out the problem. The gunsmith that sent me his reamer spec for his A.I. measured 2.560 and you are saying the normal length is 2.540. He must have an odd reamer which threw me off. I don't know why anyone would want that much extra neck length unless he was planning on chasing the lands when he shot the barrel out? Thanks.......Rich

 

[J E Custom]

OK, I think I've figured out the problem. The gunsmith that sent me his reamer spec for his A.I. measured 2.560 and you are saying the normal length is 2.540. He must have an odd reamer which threw me off. I don't know why anyone would want that much extra neck length unless he was planning on chasing the lands when he shot the barrel out? Thanks.......Rich

Some people like to change the dimensions for one reason or another and its not bad, but
if the chamber is anything but SAAME dimensions It should be noted on the barrel ID to avoid
problems.

I have found many chambers that were not SAMME spec. and were not marked on the barrel
that was causing problems for the shooter because he didn't know the chamber was different.

That increase was probably an attempt to boost performance.

As I said there is nothing wrong with 2.560 as long as you are aware of the change.

Good luck on your project.

J E CUSTOM

 

[elkaholic]

Jerry......So you don't think are are any problems associated with the bullet gapping approx. .040" of unused neck area in the chamber? That is if he uses factory A.I. brass; if he uses fireformed .280 brass, it will be more like .050"........Rich

 

[J E Custom]

Jerry......So you don't think are are any problems associated with the bullet gapping approx. .040" of unused neck area in the chamber? That is if he uses factory A.I. brass; if he uses fireformed .280 brass, it will be more like .050"........Rich

.040 or .050 thousandths shorter Case lengths does not hurt anything.

He will have to watch for carbon build up at the end of the case neck and keep it clean. But
we all have to do that, There will just be more of it in the longer chamber neck

The 280 brass is .015 longer than the 280 AI brass so he will be .020 short with the 280 rem
brass and .035 short with the factory AI brass If my math is right.

The more I look at the 2.560 chamber length It looks like the reamer is designed to fire factory
280 rem and be safe in case the factory stuff is a little long. (No trimming Is required).

J E CUSTOM

 

[elkaholic]

That is the conclusion I've come to as well. Let me back up a little and explain why this bugs me a little. I am trying to help a 19 yr. old kid get started in long range hunting. He wants to build a rifle based on my Sherman case which is a little longer bodied and has less taper than the A.I. case. I don't have a .280 reamer but I do have a 6.5 and a 300. It has proven very effective for velocity, accuracy, and case life. The gunsmith he is working with did not want to work with my case since it measures 2.525 to allow for shrinkage when fire forming either the .270 or .280 case. As you eluded to, he is very concerned about the safety factor of someone firing a loaded std .280 round with the shorter chamber. This all makes perfect sense. I asked him why he couldn't use his .280 A.I. reamer first and then clean it up with my 6.5 Sherman reamer since it is dimentionally larger in every way except length. He said that would work and that was probably what he would do. We have kind of gone around about the 2.560 neck because it seems unnecessary to me and probably not condusive to the best accuracy possible. Why could he not just run the A.I. reamer in .020" short of normal leaving a 2.540" total length and clean it up with my 6.5 Sherman which I designed for 2.525". It seems to me this would take care of any safety concerns and would be a much more reasonable fit for my case. I am not a gunsmith, however; so am I missing something?.....Rich