280AI Caseforming from 9.3x62

[Dr G]

I have read that the 280Rem brass (made by remington) is designed for autoloaders and so experiences a bit of stretching and even possibly headspace issues. I have also read on AV that several members use Lapua 9.3x62 Brass to make there cases from. These cases apparently are better at higher pressures and have longer lives.

I have a number of questions regarding the process

1. Is a intermediate neck sizing operation required?

2. Do I neck size the case down so that the neck shoulder junction is 2.175" (280AI length) or 2.1993" (280Rem length). My understanding is that when fireforming an AI case you want a crush fit at the neck shoulder junction but I could be wrong here.

3. There is a difference of 0.051" between the shoulder of the 9.3 and the 280AI is this gap safe if there is a decent neck/shoulder crush fit?

Hope you can help

Dr G

[JFE]

Bit of a curly set questions there Doc. I'll make a few general comments that might help.

1. The 9.3X62 is slightly wider in diameter than '06 based cartridges. It tends to run about .005-0.007" wider. This may or may not be an issue depending on your dies and chamber.

2. The 9.3 case is 62mm long and the 280 is 64 mm, so I'm guessing that using 9.3 cases would result in short necks ?? Also, I'm not sure whether there would be any neck thickness issues.

3. Norma did make cases for 280 AI at one time and Nosler still do.

4. When I checked several years ago Norma 280 brass had about 5-6% greater capacity than Rem and Norma was better brass all round.

Personally I'd opt to form cases from Norma 280 brass - even better if you manage to find Norma 280AI brass. If you were concerned about headspace in your AI chamber I'd neck up to 30 cal and then size down to form a secondary shoulder. As long as the case is properly held from bolt face to shoulder (crush fit) then it should form properly.

HTH

Joe

[Con]

Man oh man,
Why not just use the best quality 30/06 brass you can find? Otherwise your talking a lot of stuffing around, and every operation added to processing a case to the one you want potentially increases the reject rate and chews up your time.

Fork out for Nosler brass, or pull the trigger on some factory 280Rem, or play with some 270Win or 30/06.
Cheers...
Con

[Dr G]

Thanks Joe much appreciated.

Not to sure about the case width issue, I suspect the dies would sort this out. I know that within the benchrest crowd on this site I have seen the 9.3 LAPUA brass recomended for the 280AI over the 30-06 Brass.

Neck length again not sure but I was thinking that as you sized it down it would increase in length to offset this. This is just a guess.

I have seen the Nosler brass advertised in the US but am unaware if its sold here. I suspect it will be bloody expensive seeing the US prices so the LAPUA option will probably be cheaper. If I could get Nosler 280 it might be the viable (probably have more chance)

Agree entirely on the false shoulder I think that is how I will proceed.

Just to let you know I dont have a rifle in this calibre yet but I have ordered a 7mm barrel and intend to chamber the model 70 I am restoring in this calibre.

Before anyone starts telling me I should just get a 270, its too late and I dont want one. I want something a little unusual, something with proven accuracy and something in 7mm that will fit on a .473 boltface in a standard length action Also I have a shitload of prepped 30-06 brass that I can experiment with to get it right.

Thanks Joe

Dr G

[Dr G]

Man oh man,
Why not just use the best quality 30/06 brass you can find? Otherwise your talking a lot of stuffing around, and every operation added to processing a case to the one you want potentially increases the reject rate and chews up your time.

Fork out for Nosler brass, or pull the trigger on some factory 280Rem, or play with some 270Win or 30/06.
Cheers...
Con

G'Day Con

I am asking about the 9.3 just because I have seen posts where TonyZ used it for a 280AI they made

http://ausvarmint.kjd84.com/forum/viewt ... =10&t=7751

I asked about the intermediate steps so I could find out if it was worthwhile for me to have a play or if not then I would just use 30-06. The Lapua brass dosent have much price difference between them but I also seem to recall seeing a post of Tonys or Jeff Rodgers stateing that 9.3 was much stronger and handled pressure better than the 30-06.

If there are lots of fiddly intermediate steps I probably wouldnt bother but if it was straight forwards then I am happy paying an extra 9c/case for brass that is going to handle pressures better.

I dont mind fiddleing about prepping brass, I have a great setup at home now and find it usefull to clear my head after a shit day in the office (the enclosed one not the nice outdoor one )

Thanks for the input

Dr G

[Con]

Dr G,
Benchresters have a different point of view ... their time consuming individually prep'd cases don't end up in the paddock.

Taking a 9.3 to 7mm will require intermediate steps, how many depends on the case and the dies you use. I can go from 303Brit to 303/25 in one step and have, but its careful careful on the press handle. Much easier going 277" as an intermediate step. If the rifle will be a custom, you can have your neck diameter set to allow for any thickening that may eventuate from necking down. That is you can 'set up' the rifle to utilise thicker necked brass.

Nosler 280AI brass is available locally ... wait till you see the price. Reports from the States I've read suggest its over priced for what it is.

May pay to get some Lapua brass in 9.3 and run it through your dies. The slightly wider base spec of European brass may not be happy with your dies, then again it might be. What'll happen in your chamber though? Do you know of a reamer with European base specs ... or will the reamer specs be based on US dimensions? If you have a Euro spec chamber, will you be happy getting heaps of expansion with US brass? I suppose these are all questions that need answering before jumping in with both feet. Sounds like a good project though.

I've only just run in the barrel of my 223AI using Fiocchi 55gr FMJ loads, looking forward to starting the reloading process.
Cheers...
Con

[Dr G]

Thanks Con, This is good advice

It looks like I might be looking into necking down 30-06Lap brass to make a false shoulder to headspace on and going from there (or see what Nosler want for the standard 280Rem Brass).

I saw the US prices for the AI brass and wondered why Nosler would charge that much compared to there 280 brass. Almost like they want it to fail . Still my expertise is ecology not marketing so what would I know

I would still like to hear from the benchrest crowd that are using the 280AI though.

Dr G

[HiWall]

No need to bother with all that stuff mate, Nosler make it, a bit expensive but cheaper than Lapua and no mucking about at all.

http://www.rifleshootermag.com/new_prod ... st_200804/

http://www.nosler.com/brassshowroom.htm

I have found the Nosler stuff to be worth the bucks mate.

[a.JR]

DR, The case i designed back in 2004 was indeed based on the 9.3x62 brass ,both RWS and Lapua make it .. the final one TZ uses now is the same but with a 40 deg shoulder ..The reasoning behind it was that the factory Ammo was loaded quite high IMO and with my guess of a low 70 gn capacity ,it must be strong in the 1st place to produce those speeds with the 286/293 gn moose bullets..And the 1st 100cases i checked came up with just less than 3 thou wall thickness variation ,any where you put the ultrasonic probe.. Well it works the the Lapua brass is very good and well priced .. That said i would not put the reformed 9.3 case into a saami 280 ack chamber !!..JR..Jeff Rogers..ps if you want to order a reamer ,i will help with specs or mabye Kenny Y could be talked into chambering your barrel as he has a 7mm JAT reamer already

[Dr G]

Thanks Jeff.

I appreciate the input. Now I have a lot to digest. For the Model 70 I will probably stick with the 280AI as it will be a hunting rifle. But if we get this range happening up here then I can see a 7mmJAT Bench Rifle as a real possibility. From the conversations I have had and posts I have read it seems that this would be an ideal fly calibre (as would the 280AI).

Jeff, Tony or Kenny, if you dont mind me asking what is the net improvement of the 7mmJAT over the 280AI?

Thanks for the links HiWall

Again thanks for the posts this has cleared up quite a few of the questions I had leading into this project.

Dr G

[ogre6br]

thread hyjack- speaking of nosler brass- anyone have it in 204R
is it worth the $$ over federals?

p

[a.JR]

Hi Dr, No real gain with either, i think after 5 different 7 mms i have put together for long range the case capacity at approx of 72 gns of h2o is the right ballpark.. For wackin hairy critters go with the 280 AI and h1000 or imr 7828 ,both of these powders operate better in the 55000psi area with the 160 gn bullets and IMO you can get enough accuracy for hunting with the weak brass available without having to pitch them every 3 loadings.. For BR the best accuracy does not always coincide with low pressures.. The case we use based on the 9.3 is just the same capacity as the 280AI only about 100thou shorter,BUT you can wack the crap out of them and they just smile at ya, and i mean 65000 to 70000 psi..JR..Jeff Rogers

Thanks Jeff.

I appreciate the input. Now I have a lot to digest. For the Model 70 I will probably stick with the 280AI as it will be a hunting rifle. But if we get this range happening up here then I can see a 7mmJAT Bench Rifle as a real possibility. From the conversations I have had and posts I have read it seems that this would be an ideal fly calibre (as would the 280AI).

Jeff, Tony or Kenny, if you dont mind me asking what is the net improvement of the 7mmJAT over the 280AI?

Thanks for the links HiWall

Again thanks for the posts this has cleared up quite a few of the questions I had leading into this project.

Dr G

[Kenny]

G'day Doc,

my version is a frag different to the JAT that Geoff and Tony use...I called it the 7mmAV after all the advice and help I got from this forum which reminds me that I am expecting some flack off Keithy about it....

Anyway...I shortened my shoulder further to give a longer neck and took a lot of taper out of it...I find it is just about right capacity wise and as Jeffro said they can take a hiding in the pressure dept...as for smacking large rodents at long range.....I have never tried it....but it will drill a nice hole through 1/2" steel plate at 300yds

KY

[Con]

Just to keep this off-topic!

Why not the 7mmSAUM for the target inclined applications? Capacity is about what you guys are using from memory. Is it a lack of quality brass, problems with the case or chambering ... or what?
Cheers...
Con

[Dr G]

thanks Jeff, your input is much appreciated

280AI it will be for the Model70, I wont be needing the pressures you have described for what I intend to use it for.


thanks Kenny, I suspect anything punching through 1/2" plate at 300m is going to have more than enough stopping power for any large feral

If we get this range happening and I get to build a fly rifle I will definately be bending yours, Jeffs and Tony's ear


Thanks

Dr G