Hey guys, I have three loads that I need some info on for my 280AI. I am not seeing obvious pressure signs but am curious as to the expected or close to actual pressures that I am running. The numbers from the chrony don't seem to far fetched but they have me wondering. If someone would be willing to help me out I would greatly appreciate it. I can't find the old topics to know what info to provide.
Thanks,
Alan

So what is your load, barrel length, AOL and chrono readings? (H2O capacity for one of your fired cases with case length would be helpful, but not necessary)

I get 3133fps avg from a "standard" 280Rem in a 24" barrel using a Nosler 140gr Accubond and Vv N560.

According to my "Quickload" data, I am above SAAMI spec for 280Rem but still within SAAMI spec for 270Win. Unless you are shooting the 280 in a M742 Rem or other (relatively) weak action the SAAMI pressure spec for 280Rem is somewhat lower than what one could safely use in a modern bolt gun.

Wildcat, I will have that info for you Sunday eve. I have a deep sea trip scheduled for sunday morning, I'm hoping the big boys are hungry........
Thank you.

Alan

Wildcat Junkie, Sorry this took so long, we were cutting up tuna and grouper all night sunday, and work got the best of me so far this week.
Thanks for your help,
Alan

280 AI 40*

Load 1
63.0 gr RL-22
CCI 200 LRP
Case Capacity water, 73.3 gr.
140 gr. Nosler Partition
24 inch bbl
OAL, 3.366
3273 fps avg.
.4 avg

Load 2
57.0 gr IMR 4831
CCI 200 LRP
Case Capacity water, 73.3 gr.
140 gr. Nosler Balistic Tip
24 inch bbl
OAL, 3.382
3168 fps avg.
.4 avg

Load 3
60.0 gr IMR 4831
CCI 200 LRP
Case Capacity water, 73.3 gr.
115 gr Speer Hollow Point
24 inch bbl
OAL, 3.253
3261 fps avg.
1.0 avg

Take into account, the chronograph readings seemed erratic, even though the groups were good. There have not been any loose primers or over pressure signs but some of the brass work hardened and I did anneal all of them after that.

Carnivore;

Check your private messaging.

What are you expecting for increased velocity?
Velocity generally increases at one fourth the percentage of increase in powder. So if you increase a 57 grain load by 2 grains (without filling the case, you'll increase powder volume by 3.5% but velocity at less than 1%. That computes to an increase of less than 50 fps (and higher pressures) to a bullet that was going 2850 with 57 grains. That assumes the barrel length is the same for a 280 and a 280AI. Now if you campare a lower pressure load in a straight 280 to a hot rod load in an AI chambering you will get a greater difference, of course. But that isn't comparing apples to apples.

The only real benfit in an AI is that you can max out a slow burning powder to the point of creating a compressed load in the AI that would not have fit in the standard cartridge. The velocity achieved from non-compressed loads that would fit either cartridge can be achieved ( but not recommended) by hot rodding either.

Cossack, I don't really know what I am looking for. The gun is a toy at this point and I am still trying to get the feel for it and the right loads. The go to gun is a Sako in '06 that never misses. I just figured I'd give the AI a try. I like the brass life, it shoots extremely well, and it just looks cool.
I simply am trying to find a load that is speedy, safe and accurate that can be backed up with some solid data on pressures. Most times a fella doesn't need a reason to build a gun except I felt like it.

Wildcat Junkie, I recieved your reply and if I ever figure out this PM thing I will get back to you in a few days. I'm trying to figure out what to use as a baseline to know if the chrony works right.

Check out the pics in the fishing section... , that is why I didn't get back to you sooner.
Thanks,
Alan

Carnivore,
I don't mean to sound like I'm putting you down for the AI thing. And yours are definitely good enough reasons to do it. I shoot half dozen wildcats myself....some for the same reasons. But it's just that some folks have unrealistic expectations for velocity increase when going AI. The relatively small increase in powder capacity just doesn't make that possible.They often attribute velocity gain to AI'ing; when in relity it's due to the substantially increased operating pressure of their AI loads.
The 280 AI will safely approximate factory loads for the 7mm Rem Mag when using the same bullet. If it's just speed you want, you will need a much bigger case...like the 7mm STW. If I was seeking to maximize safe performance (accuracy and terminal energy)of an existing 280 AI chambering I'd focus on a premium bullet (like the 140 Barnes TSX) and the powder that produces a load fitting into the AI case... but greater than the conventional case will hold.
For example, using a 140 gr bullet, you can't get enough Reloader 25 into a conventional case to produce the desired 3000 fps. But the increase in powder capacity allows you build a safe (albeit compressed) load in the AI'd case with Rl 25 that does 3050.
Generally speaking, the slowest burning powder, that completely fills the case at desired pressure, has the greatest potential to be the fastest most accurate load. That's why I suggest a focus on powders that fill the AI case but won't fit/reach max safe operating pressure in the conventional case. Generally speaking, again, such powders are relatively few in number. Having identified them, I'd start my work-up with one or more and use 280 data as a referance. I'd use it as a comparison to develop starting loads, then work up loads that do not exceed the velocity expectations derived by the formula I mentioned above: velocity increases at one fourth the percentage of powder increase. Individual wildcats have no standards..except what was produced in a different rifle by someone who may or may not adhere to (or even know about) safe operating pressures. In that case, it's best to err on the conservative side....and to keep expectations for velocity gain the same...in all probability not more than 100 fps difference in comperably safe max loads.