280 AI chamber length

[JimOK]

This is my first post. I hope I put in the correct place.

I used a Sinclair Chamber length gauge in the gun and it measured out at 2.566. This is the old original 280 ai chamber - not the SAAMI spec.

Most of my cases come out to 2.510 +- after fire forming and I have always just kept them trimmed to 2.510.

I havent found a lot of really good info about what the old 280ai max case length should be but some sources have said anywhere from 2.515 to 2.525. I also found a drawing that showed 2.540.

Is 2.566 out of line? or am I missing something?

I do have accuracy problems with most loads that I shoot out of this gun 2MOA+. I found one load that shoots good ~.75 MOA but it is a little hot for my liking and I am trying to find another load that works.

Additional info: cartridge length to where ogive hits lands is 2.749.

Thanks

 

[Maxxis31]

I also have the old Ackley chamber in my 280AI. My oal is 2.700 (where bullet hits the lands) with Berger VLD 168's, I am seating to a COAL of 2.689 putting me .011 off. I would think it will be different depending on the bullet you are using.

I have been using Retumbo with good luck and it is almost impossible to get it too hot. I am shooting 63gr which is book max but shoot 64gr with no pressure signs or stiff bolt, I don't think it would be possible to get much more powder in the case as even 62gr is a compressed loads with the VLD. I am using BR2 primers and Norma brass, I have not trimmed my brass at all or even measured it after 3 firings???

I am using the SAAMI spec. dies and setting them .014 back so I don't bump the shoulder. The rifle has shoot extremely well through load development and Almost never shoots over MOA even while fireforming with cheap quick loads.

My rifle is a 700 action, blueprinted and has a 25" Walther barrel, I bought it off of here about a month ago and absolutely love it.

What rifle do you have, How heavy of bullets are you shooting? Have you tried jump shooting? Any load data? I had to jump shoot the last rifle I tried with VLD's and ended up settling on .090 off the lands.

I also talked to a couple guys who ended up shooting 140gr bullets out of their 280AI because they couldn't get heavier bullets to shoot??? Personally i believe you are not using the rifle to its potential using that light of a bullet and it will be passed up by several smaller calibers when shooting bullets under 150gr. If you have a decent lenth barrel with a 1:9 twist you should be stabilizing pretty much every bullet offered for the .284.

Also a little info about yourself is kind of the norm as a first time poster, there have been lots of people on here helping me out quite a bit thought P.M.'s when I was developing a load for my rifle. It is very possible that it is not the load but some under lying issue, loose mount, barrel not floated, rifle ratchet strapped to a 2x4, ect. A little more detail would be great. By nature most 280's Ackley or Standard shoot inherently well.

Welcome to the Forum

 

[Maxxis31]

I estimated my Velocity to be about 2850fps but after shooting at 600 yards and recalculating it for the drop (or lack of) it came in right at 2945fps.

 

[pods8]

Most of my cases come out to 2.510 +- after fire forming and I have always just kept them trimmed to 2.510.

I havent found a lot of really good info about what the old 280ai max case length should be but some sources have said anywhere from 2.515 to 2.525. I also found a drawing that showed 2.540.

Is 2.566 out of line? or am I missing something?

280rem trim length is 2.53", sammi 280 ackley trim length is 2.53", I see no reason the traditional wouldn't also be 2.53" (that's what I was planning on trimming mine to when I get my gun soon done traditional). 2.54" is the max case length for 280rem to my knowledge (note case not COAL).

The 2.5xx numbers you are throwing around is chamber length (for the neck), which has to be longer than the brass case length to avoid interference.

 

[JimOK]

Thanks guys for your help.

A little about my gun. It is a Remington 700 blue printed action, 26" douglas air gauge barrel 1:9 twist, HS precision stock. I have had it for about 6 years and have used it for closer range whitetail deer hunting here in Oklahoma. Over the past 6 years I have tried many different loads with 10+ different bullets. The best I was able to get was with the Swift Scirocco 150gr. I was getting about 1MOA with that bullet.

Currently I am trying to extend the range of the gun (and my shooting abilities) so I am trying to find a more accurate load with a bullet that has better terminal ballistics downrange than the Scirocco.

Lately I have tried various loads with the 162 amax and the 168 Berger VLD Hunting bullet. I was able to get about .75 MOA with the 168 VLD with 56.5gr h4831sc .045 off the lands but it was flattening the primers pretty good (2746fps). So I am now switching to IMr 7828Ssc to try to get increased or the same velocity and less pressure.

I have tried to jump the bergers various distances and I have 5 more loads ready to go to the range this weekend with the 7828ssc powder jumping .001 off the lands to .12 off.

I should reword my question better: Is it a problem for my brass to be .056 shorter than my chamber length?

 

[pods8]

You didn't mention your powder charge method, are you running a ladder?