280AI - Help sorting load data...

I've gone down a rabbit hole here and likely over thinking it but could use a bit of advice on load development and where to go for data. I'm loading for a 280AI 22" barrel with 1:8.5 twist. Suppressed if it matters. Long throat chamber in a Rem 700 so plenty of mag space. Seating to a COAL of 3.490 puts me 0.020 off the lands. I was setting up last night for my first round of loads for this rifle and originally settled on AR2209. Main reason is because I can also use it in my 260 and my mates 7/08 so I'm only stocking one powder.

I've looked at ADI and they show 50.6g as a max load, relatively slow and well under max pressure. Their data is odd as the 162g projectile has less powder than the 168g. They are also saying that a 284W will get more speed, at less pressure, with more powder behind the same projectile so I'm sceptical. I've looked at some data from Quick Load, it's showing a max load of 60g but that's quite hot and just under max pressure. I'm also led to believe that AR2209 is the exact same as H4350 and when I look at load data for H4350 it's higher than ADI as well.

Ultimately I want to keep things safe but if I could get the 162eldx to hit 2900 from a 22" barrel I would be pretty happy. I'm limited on range time so try to make the most of it. I still need to finish zeroing my scope so I've loaded up 15 rounds at 50.5g AR2209 to get things dialled in. My plan after that is to start moving up in 0.5g increments until I see pressure. Issue here is that's potentially 20 lots of 3 rounds to get to the Quick Load max of 60g which is a lot of time and ammo and gets well outside of the ADI load data.

Anyone have any insight into the extreme differences in load data that I'm seeing available and how to safely mitigate that without burning through a significant amount of time and ammo?

First off. There is something....about the eld.blah blah around that weight,something about one being harder to push,more bearing surface??? Might be the pressure thing and reason for lighter loading. I would have thought ar2213 would be better option for larger case,but see where you coming from with desire to share powder. .5 of a grain is tiny jumps in big case. As your doing it to look for pressure etc maybe increase in whole grain lots instead. I don't know your rifle,or what it's liked in past so can't recommend jumping ahead with shortcut. But a maximum .280 load SHOULD be below max in AI case... See what the book numbers say for std case perhaps.

Interestingly your book values are one through one and half grains above the std 270w. Right through weight ranges. Looking at you desire....... Maybe that is unrealistic given book value for 24" barrel 280AI can achieve that speed with only one of the 150grn loads and all but one of the 140s....even the 160 GRN loads listed top out at 2800fps.

Attachment 280185

Do a charge ladder starting at adi book mid (lowish pressure right?) going up in 0.4 grain increments eg 50.2, 50.6, 51.0, 51.4, 51.8, 52.2, 52.4, 52.8, 53.2. Go shoot them over a chronograph starting with the lowest. Keep a note on which projectile hit where while holding the same point of aim. Shoot at least two fouler shots before shooting the test loads to eliminate 1st round slow velocity etc.
If pressure sign shows on the brass dont shoot anymore.
Use the charge weight 2 below whichever showed pressure sign on brass. Job done.

162g @ 2900 using 2209 is likely unrealistic from a 22-inch barrel.

I can only get close with N165 from a 24-inch barrel @ 60g (kids, don’t try this at home!)

You might want to consider a slower powder 2213SC or 17 but even then, expect to be disappointed if 2900 is your expected velocity.

I wouldn't think you will get close to 2900 with ADI powder maybe with RL26.
2750-2800 would be more realistic with 2209 I would try

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Thanks gents. Appreciate the feedback. I shall lower expectations accordingly. At the range on Sunday so we'll see how she goes.

You need to go to slower burning powders for 160+ gn projectiles. My experience with 280ai (24in bbl) is the go to powder is N560 - thats getting me 2980fps with 162AMAX & 2900 fps with 175gn Berger EH. So with the right powders 2900 of there abouts from 22in bbl is not out of the question. Also had good success with RL22 & 2217 and use 2213SC for 150gn bush load. You won’t get quite the same velocities but best pick of ADI powder for 162s would be 2217. See recent range trip to check zero for 150s and 162AMAX
Attachment 280190

To put it in perspective how hot your asking rifle to go to/ handle.... Compare velocity the 7mm rem mag has with the same projectiles weights....

Yep, 280ai is nipping on the heels of 7RM & burning 10gn less powder. The 280ai is within 20 -40 fps from my experience with several RMs and pushing close to max safe loads in both rifles.

I used to own a 280AI on a Sako Finbear action that the late Din Collings rebarrelled for me 27 years ago. I sold the rifle a year ago.

In the late 1990s, there was virtually no reliable load data available for NZ powders. I had do the old school development of starting with 280 rem data which was low pressure (50,000 CUP) and then build up slowly. I tried AR2209 (H4350), AR 2213SC (H4831), Vitahvouri N160, Re19, Re22, Norma MRP, IMR 4831etc. I tried 139 gr to 160 gr bullets and got good accurate hunting loads ranging from 3200 fps for 139 grs to just about 3000 fps with 160 gr Accubonds using VV N560. I found best results with N560 & IMR 4831 (not always available). All my load development was by carefully measuring case expansion above the web. I probably measured over 300 cases over 2 years of load development. Finally I got a new Nosler manual and found they had a load for 160 gr Accubons using N560 that gave the same results in my rifle.

I still have all the load info. PM me and I am happy to share the info as well as some old magazine articles.

I bought a Kimber Montana weighing 5 lbs 3 oz in 7mm08 and loved it so much that I stopped using the 280AI.

Used n560 and 162 Amax when my t3 was a 7mm rem mag it produced very good velocity and accuracy.

Tried it in the 7saum thinking I would get similar results but didn’t.

Im useing 2209 in my 280AI. I get very close to book numbers. Its not the best powder for sure, but its so far been incredibly consistent.

Interesting that your looking for a hot 2900 fps load behind a 160 for the wife?

Your shooting the 7/08. Must be luv.


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