new rifle .280 AI

[Brithunter]

Hi All,

I am in the process of building a rifle up with the .280AI chambering and am awaiting it's return from the Birmingham Proof house. The dealer who got the BSA CF2 7x64 barrel for it cannot put the rifle on my ticket until it's proofed. Required by law here.

Here is what it looked like before I took that old stock off and sent it to proof:-







The receiver is a 68 vintage BSA 1st Pattern Monarch that was originally a .270 but the barrel was quite worn. The idea behind the .280AI was to have a modern version to the old .280 Ross. Anyway it was worked out that using a later CF2 barrel that has a heavier breech section in 7x64 it could be fitted to the Monarch action and reamed to 280AI.

No one seemed to know that the Monarch and CF2 have different barrel tenons even if the thread is the same, the BSA barrel was chambered and threaded in the white, so I had to lenghten the tenon and deepen the bolts counter bore then work out the depth for remaing and ream the chamber. It all worked out and this is the first cartridge fired in the new improved chamber:-


I fired Six in all and used three to make up dummies to check feeding and chambering and and the other three were cleaned and sized for the proof house to use to make up their proof rounds.

Barrel has turned out at 23" in length and the muzzle has a 1/2" UNF thread to accept a Sound Moderator or Muzzle Brake should one so wish to use one:-



Sound Mods, often called silencers, are commonly used here now for deer stalking (hunting) so it seemed a good idea to adapt the barrel while it was set up in the lathe. Now I cleaned the bore of all jacket fouling before it went to proof, the barrel is hammer forged and the rifling 1 in 10" twist and is very smooth with 5 grooves and a left hand twist.

Now until I read through the 7mm-06 thread the idea of cast bullet use in this had not occured to me but perhaps with the price of jacket bullets here in the UK now cast bullets would be an excellent idea. Now I also have a BSA CF2 in 7x57 which has the same barrel/rifling specs so a cast bullet suitable for both would be just ticket.

Although it's not set up due to lack of space right now I have a electric lead pot and also have an old Lyman 450 plus a Saeco sizer but no dies for them. Which would be best to use? .............. I do have some lead both soft in the form of water pipe and building flashing and also some hard lead alloy. Oh yes and some mould handles that fit Lyman double cavity moulds and are currently attached to a pair of .35cal Lyman rifle moulds I picked up.

Now would the Lee 7mm 130Gr mould #90360 be suitable? Or would this be better;-

Lyman 2-Cavity Bullet Mold #287346 284 Caliber, 7mm (285 Diameter) 135 Grain Round Nose Gas Check.

Your thoughts would be appreciated.

[Bass Ackward]

Bullet choice depends on use. OR .... the guns preference. Nobody can tell you that.

My problem with the 280 AI was that I had experience with a standard before I chambered it out.

The sloping case side of a 280 allowed powder to roll back down towards the primer after recoil had pushed it forward. And the sloping shoulder elongated pressure so it was easier to find a slow powder for HV use.

The 280 AI doesn't offer those advantages. So you will need to learn about filler use. The sharp shoulder enhances burn which is another way of saying it enhances pressure rate. Not good for cast, so you will need a way slower powder for it than the standard. Which is OK, cause you got more case to fill anyway right?

[280Ackley]

I've had very good luck with the Lee soupcan. It's what I use for case forming. I'm currently experminting with the 7mm Hunter group buy. I don't have any experience with trying to push them with slow powders that would require the use of fillers. I just dump 10 grn of Unique or 16 grn of 2400 and go shoot. Cheap fun and plenty accurate for killing milk jugs and such.

[white eagle]

you are going to love the cal
I built one on a Winchester Model 70 action
I have a mold coming from Mountain Molds
I am going to be searching for lots of powder to fill the case
I don't like the idea of fillers ,but.....
nice rifle you got there wish we could use suppressors here

[scrapcan]

I hope you kept the old stock. I like it and it makes the gun look nice.

If you were on this side of the pond you could use Hornady custom brass, but shipping and VAT might be expensive to get to you through a distributor.

I have nothing else to offer but what is in the 7mm-06 thread.

But thanks for sharing the photos.

[Von Gruff]

Brithunter, so you didn't get it back before the end of year break. You must still be on tenterhooks as to the storage conditions at the proofhouse. Do you have a date or expected delivery yet. If you have the option I would look to the 160gn weight in a cast boolit for your 280 AI.

Von Gruff.

[Brithunter]

No it's still at the proof house until next week at least. Fingers crossed it has no rust on it. There is a show in Febuary ( Newark showground) that I will go to and see if I can find any moulds on offer if not it means the one in March at Bisley or buying new to order. There are a couple of commercial casting outfits here in the UK so perhaps I could buy a few different types to try out before deciding upon weight and shape. That might be the way to go.

Now manleyjt, we have Midway.UK but the price of Nosler brass is stupid. How about $206US for 100 pieces of brass.

As for the stock I am afraid it looks better than it is. A previous owner sanded off the chequering from the forestock and ripped out the barrel channel in an attempt to free float the barrel. The CF2 barrel used in the conversion and re-build is of a slightly heavier profile so fill the channel better but the forestock is still extremly slim. Once finaces permit a new stock of the same profile will be acquired. This is what it should look like:-


That's my 59 vintage Majestic Featherweight .270 and this was the original barrel profile:-


you can compare the difference and see how much wood they took out of the stock. The original Monarch stock is this one:-


Which is similar in profile to the Rem 700. That stock is now on the 2nd .270 Majestic Featherweight as the barrel profile matches. I have to make sure the bedding is correct but in a quick test after de-coppering the Majestics barrel it shoots quite well.

Now 280Ackley, when making my 6.5x53R brass and fireforming it I use a fast pistol powder and tissue paper tamped down into the case and no bullet at all. I will be gettign 100 or 200 pieces of Remington 280 brass in a week or two.

Oh thank you all for the ideas and nice comments about the rifle.

Once finished polished and hot blued it should look much better. It will have a screw on Williams ramp at the muzzle and a Lyman 57SME receiver sight plus a scope so I have plenty to work with this coming year.

[runfiverun]

my x57 ackley does fine with the rcbs 145.
i also just use standard loads for cast in it.
the wifes had a standard chamber at the time and the velocity difference was 20 fps in her favor.
the remington brass fireforms nicely in the ackley chambers if you use standard cast loads it may take 2-3 loads to get a full fireform.
just neck size and you'll be fine.
anneal the necks about every 5-6 loads and your brass will last a long time.

i really like the looks of those rifles and their stocks too.