280 AI project revisited

Technically I know the difference in case lengths should make no difference as long as the cases are uniformly the same length within each group--but I've shot one of the better SD groups 4 times now--twice with Nosler's stock shorter length--and twice with longer case OAL around 2.525--and the spread with the shorter cases is generally twice or more the size of the groups using the longer cases.
 
Trim length 280AI is 2.515". Are you saying Nosler brass is shorter. You ask question and I sure answer them and I expect same from you.
 
What is trim length on Nolser brass you? Please don't send me another private message telling you history on 280AI barrels.
 
What is trim length on Nolser brass you? Please don't send me another private message telling you history on 280AI barrels.
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After two to three firings they vary between 2.514 and 2.518. I get what you're saying--let the case stretch and flow and then trim it to 2.515 which is what you elected to do.

This is getting academic as I have already decided the only way to resolve this is get an accurate measurement from bolt breach face to case mouth for my particular rifle.

Thank you for your help, we're done.
 
The Chamber Length Gage just came in--mine measures at 2.582 chamber case mouth to bolt breech face. Hornady's max length does seem excessive, but their trim length looks realistic to me.
 
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I loaded up some cartridges with the brand new Nosler stuff yesterday to test, 4 of the 12 cartridges I loaded the bolt would not close on without significant resistance. Some is good, but this was "jamming." After getting the chamber measurement above I double-checked "just in case" my headspace with both go /no go gauges and that checked out, and then compared the headspace on unfired and fired brass with a comparator and came up with .139 - .135 = .004, assuming a stretch of +.001 that should put the headspace within compliance. So far--the "top winner" for over-all best reloading brass in my rifle is FC's nickel-coated brass that I recycled from their (very expensive) factory ammo.
 
Hornady new manual has max case length 2.525", trim length 2.515" for 280AI. I was just thinking if you want I'll send you 10 new 280AI Peterson cases and they @ 2.520". Just PM your address.
 
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Hornady new manual has max case length 2.525", trim length 2.515" for 280AI. I was just thinking if you want I'll send you 10 new 280AI Peterson cases and they @ 2.520". Just PM your address.
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Thank you very much for your kind offer--I actually have hundreds of cases--besides Nosler I also have plenty of Hornady and FC cases. They range in all kinds of sizes and neck lengths so I'm covered.;) However, as soon as Petersons become available again I'll be getting some--I prefer their brass and ADG's for my creedmoors.

There appears to be many "flavors" of what is called the 280 AI--40degree shoulder, and I have a strong suspicion that's why Nosler and others are defaulting to a "small base" size; this permits a wide range of chambers to fireform-to-fit the case Problem with that, as I see it, is that causes quite dynamic shifting/flow of the brass, the necks in particular I believe are prone to a thinning as they grow in length. I've also found that the case diameters expand out as well. I want the brass to stay as uniform and last as long as possible. But I'm still new to the cartridge. The more I use it--the more amazed I am of it's over-all performance; perhaps one of the top designs ever.
 
Found a box of 183 gr matchkings stashed away that I didn't know I had--seemed like a reasonable step down from the 190 bergers so gave a couple low end charges a try today. The winds were too gusty to set up the labradar and I moved a bit closer than usual, but these look promising as well.
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stagpanther, I didn't know anyone was making SB sizer for 280AI. I have old 280AI wildcat (280 Remington IMP 40) Body Die from Redding # 75428. Redding dropped all dies for that wildcat and I have Redding body die for Spec 280 Ack Imp #75428.
 
The term "small base" is a bit confusing to me, most full-length sizing dies I use are dimensioned towards the lower-end of SAAMI tolerances whether they expressly say so or not.

So far (I'm still new to the cartridge and learning it's behavior), I use three dies for the 280 AI--A Redding full length type S comp # 36428 for "after first firing" (because that's when all the case dimensions are adjusting themselves to my rifle's headspace and chamber dimensions)--and after the brass headspace and shoulder takes a set to my particular chamber's dimension I use the Redding competition bushing neck sizing # 56428 and seater die.

The area around the shoulder seems to undergo shifting depending on the set to the chamber and the brass' "starting" dimension. The base of the shoulder and immediately behind it I've found can expand and/or form an "external donut" if the shoulder compresses in firing or sizing. So far, Federal's nickel-plated brass seems to be the best for my particular set-up because it appears to take and keep a set to my chamber with minimal changes in the cases's dimensions upon repeated firings and sizings. There's a .001 difference between the federal and all-brass cases after firing; the all-brass having expanded more and seems to have thinner neck wall with more flow.

Or I could be totally nuts and imagining things.:)

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stagpanther said:
Found a box of 183 gr matchkings stashed away that I didn't know I had--seemed like a reasonable step down from the 190 bergers so gave a couple low end charges a try today. The winds were too gusty to set up the labradar and I moved a bit closer than usual, but these look promising as well.
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Hey, what’s going on here? I don’t see the obligatory flyer. LOL.
 
Hey, what’s going on here? I don’t see the obligatory flyer. LOL.
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What you don't see is the other groups that do have the obligatory flyer--this one was an aberration in that somehow `I held it together for all 5 shots.:D Winds aren't quite as strong today (10 to 20 mph) so I'll give it a try with the labradar.
 
Ever had one of those days when all the many hours of disciplined shooting--slavishly pursuing the best handloads using the best equipment and components available--and perfect weather presents itself and it all comes together in that magic moment of perfect shooting and the best groups you have ever shot?

Well, today wasn't one of them for me.:rolleyes: In fact, I managed to drill in several shots almost exactly in the POA--and then proceed to pull the next couple shots so badly I had problems figuring which grouping they belonged too. But I did at least get a few of the groups on the labradar so it wasn't a total waste.
 
Decided to get serious and do some upgrades. Off with the vortex diamondback and on with the nightforce force SHV. Off with the accutrigger and on with the rifle basix. Most importantly, I finally got completely fed up with my caldwell Unstable Table and have embarked on devising a system to keep it more steady. First I'll be adding two extra lock bolts--the supplied ones only guarantee that the wobble will get worse over time. I'm also going to add some additional braces to the table top--that thing is about as solid as a cooked noodle.
 
Found a box of federal's terminal ascent at the LGS and bought it simply for the brass. Very interesting ammunition, not only is the case nickel plated--but so is the tipped bullet, which I assume is a special version of their fusion bullet. I've never seen that in any other production ammunition or bullets. I've fired Federal's premium 280 AI which uses the berger 168 hunting vlds and they are exceptionally accurate for production ammo--really looking forward to seeing how these do.
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