Removing a Browning X Bolt barrel

[Eldon]

Found an almost new one in 280 Rem with a 26" bbl for little $.

Wanted to take bbl. off to rechamber to 280 AI.

Found some things of interest:

- Browning uses locktite on bbl threads, a few minutes with a propane torch fixes that.

- A 700 action wrench fits.

- Browning uses a removable recoil lug between the bbl and action. It also controls headspace.
So if, as in the 280 AI, the SAMMI headspace is shorter than the parent cartridge, headspace can be adjusted
by shimming or thinning the lug.

- If thinning, be sure to consider bolt face/barrel face contact. As with putting a Savage bbl in a Marlin X7, some mill filing of the bbl face may be required.

- The AI's SAMMI headspace in .004 less than the 280 Rem. Given the large differences in cases among various makers, IMO .004 is not significant. If factory AI ammo misfires, the X Bolt design provides a simple fix compared to say a 98 Mauser.

- Ackley's reason for that .004 was to provide a "crush fit" when fireforming from 280 Rem cases.

- Apparently he was unaware of the "false shoulder" method of fireforming that would have allowed the parent and offspring to have exactly the same headspace.

[roysha]

- "Apparently he was unaware of the "false shoulder" method of fireforming that would have allowed the parent and offspring to have exactly the same headspace."

You are kidding, right? Ackley probably forgot more about "wildcatting" and "improving" cartridges that most of us will ever know.

How in the world do you put a false shoulder on a factory round? One of the claimed advantages of the so called "Improved" cartridges is the fact that factory ammunition can be fired in an "Improved" chamber either to fire form the brass or, in the case of losing or running out of reloads, one can still shoot using the factory ammunition, albeit with probably reduced performance.

[Eldon]

Owning everything Ackley ever wrote I can find no mention of false shoulder headspacing in his writings. If you have a link, please post it.

As I said, .004 is nothing when it comes to headspace. Anyone who thinks otherwise needs to buy an M-1 that shot 100s of thousands of rounds with, typically, .007 slop.

Dollar to a dime that a 280 AI chamber cut to 280 Rem depth (.004 longer) would show a "crush fit" with some 280 Rem ammo and none with others. Certainly any 280 Rem formed from thick GI or NM brass would "crush".

Dollar to a dime, it would also work just fine with 280 AI factory ammo as plenty of factory chambers in plenty of chamberings, cut when the reamers were brand new, exhibit more headspace than when the reamers were nearing the end of life.

ALL factory loads are undersize as they have to fit the tightest factory chamber out there. Yet to see a factory chamber that required any effort to close the bolt on a factory round.

The AI headspace issue is an answer in search of a problem. Almost as silly as the 308 vs 30-06 debate (before you rant, 1/10 of 1% of people use 220 gr bullets in a 30-06)

[Nobade]

Ha, I can't count how many rifles I have repaired that had been converted to ack imp and then kept having case head separations because somebody was thinking like that. But if you wish to put it to the test, just pop a primer in an empty case and see if it sticking up afterwards. If it is, that is how much excess headspace your rifle has for that particular piece of brass. Normally it takes about .010" extra stickout on a go gauge to make an Ackley rifle work right. You want it to be fairly difficult to close on a factory round, so it will support the case properly. Now that Nosler is making 280 imp cases, things are different there. They don't headspace the same as a formed factory round. I have to ask my customer if they will be using that brass, and if so set the rifle up looser than if they weren't. And when I do that, it will stretch factory 280 cases if they are used. Thankfully no other caliber is offered that way, it has caused me a major headache once they started that.

[Eldon]

Think you need to read this:

https://gunsmithtalk.wordpress.com/2...eadspace-test/

As I said, the shoulder/neck intersection in a perfect 280 Rem chamber is .004 greater than a perfect 280 AI chamber.

That's what P.O. specified and that is the SAMMI difference.

Nosler cases headspace just like any other rimless cartridge ..... at the neck/shoulder junction. IF there is actually that .004 difference between the brass and the chamber, it will expand to fit the chamber and no primers will pop out ..... just as ALL undersized factory cartridges expand to fit chambers with no popped primers.

Popping a primer on an empty case proves nothing except that all factory rimless cases are undersized so they fit ANY chamber.

The trouble starts when cases are "bump over" full length sized a few times to minimums and fired in a SAMMI or worse a military chamber. This is true of any high intensity rimless cartridge.

[B R Shooter]

Do a search here, I was involved in a long discussion about the 280AI, and fireforming brass. Eldon is right, the accepted ".004" is a wild a$$ guess to the thickness of the brass, there are many that vary more. It's a **** shoot if you find a particular lot of factory ammo that will crush properly to fireform.

(edit....after posting I see the ***, who woulda thought c r a p would raise a flag?)

Personally, I don't think anyone should have a AI gun if they aren't an experienced reloader. And add to that someone that understands what it takes to truly fireform brass.

Fireforming an AI is a cakewalk, compared to may other popular cartridges. The most popluar is the 6DASHER. If you have a problem fireforming a case a mere .004", try moving the shoulder .100"! It's not hard, you just have to understand what you are doing. And forming a false shoulder on brass is by far the most reliable method. Long seating bullets don't always work, because there isn't enough bullet grip and the bullet won't hold the case against the boltface hard enough.

[Nobade]

Agreed. Forming AI is just a matter of firing factory ammo in your AI rifle. If the rifle is built properly. The problem comes in that so many gunsmiths don't understand what is happening with AI cartridges, and don't set the rifles up correctly. As for headspace, an AI rifle headspaces on the shoulder like anything else once the case is formed. But that first firing with factory ammo has it headspacing on the neck/shoulder junction. Just a point. It needs to be properly supported for that initial firing so the shoulder can blow forward, the body taper blow out, but not stretch at the head. The problem with the Nosler brass is it is already formed, so it is going to headspace on the shoulder. If the rifle is built to close on that brass, it doesn't properly support a non-AI case to allow it to form without stretching at the web. Yes, it works. But case life is shorter than it should be. I don't like to set up rifles that loose but in the case of the 280 I have to so the Nosler brass can be used.

[Eldon]

If an A.I. chamber is set up to SAMMI spec, the Nosler brass will work perfectly and as P.O. planned, a regular 280 Rem will be a light crush fit in the chamber, it will fireform as he intended.

If a chamber is set up with 280 Rem headspace, the neck/shoulder junction will be .004 forward of a SAMMI A.I. chamber.

Whether or not that will be enough to cause a misfire, I don't know. I tend to doubt it as my M-1, 03A3 and several late K98s will accept a +.007 gauge and still always go bang.

As I said, were there to be a misfire issue AND you insisted on using factory ammo, in a Savage/Marlin X7 rig, it's easy to mill file off the barrel face to decrease the headspace. In the X Bolt, I'm working on, the recoil lug can be thinned to move the chamber back. If moving the barrel back, creates a hit on the bolt face, the barrel face can be mill filed as with the Savage.

I really think this is a complete non event. In spite of all the ranting, I have seen no horror stories of any 280 A.I. rifles blowing up using factory ammo. As far a web stretching goes ALL factory ammo fired in ALL factory chambers stretches. Why ? Because all factory ammo has to fit all factory chambers, so it has to be undersized in all dimensions.

The real enemy of brass is not chamber size. It is the FL sizing die. If you want long brass life, never fire a factory cartridge. Buy new brass and follow the false shoulder drill. Then only use a collet neck sizing die or one of the bushing dies. When chambering becomes difficult use a shoulder bump die and precesion shell holders to set the shoulder back just enough to ease chambering.

All of this information has been/is covered in numerous books on loading as well as Handloader magazine.

I wonder why it is even a subject of debate or ignorance ?

[Eldon]

Finished up the job. The AI loaded rounds go in with a tiny effort. The only 280 Rem cases I had were range pickups that chambered with no effort. I necked them up to 30 and ran them in the AI FL die until they are a stiff bolt push down. Loaded with mid level 280 Rem load 4350 and 160 Sierras. Anticipate no issues as I made 100s of 25-06 cases the same way back before any SAMMI specs or factory ammo existed.

Off to range tomorrow to shoot it and the Argentine.

[Eldon]

Took 10 round to the range. 1 @ 25 to get centered. 3, 3 shot groups @100 w/2-7 Khales. 1.25", .75", .4".

Anybody want to buy a 280 AI reamer used once ?

[Rifle 57]

Took 10 round to the range. 1 @ 25 to get centered. 3, 3 shot groups @100 w/2-7 Khales. 1.25", .75", .4".

Anybody want to buy a 280 AI reamer used once ?

How much and what neck diameter is it and what is the free bore lenth?

[Eldon]

Came from Brownells. made by Manson.

513-050-295WB
Rimless Rifle Cartridge, .280 Remington Ackley Imp. 40/
Mfr Part: F280ACK
Cost me $112.50 TMD

It's long enough that you could put the shoulder even farther out if you wanted to have a pure wildcat to match 7mm RM.

[Eldon]

Going on Ebay ----- you snooze you lose.