Pressure Signs in .280 AI

[Loyalist84]

Hi all,

I'll have photos up tomorrow to illustrate the problems I'm having, but hoping I can get some advice in the mean time. I was sighting in my .280 AI, a rifle I bought from a fellow CGN'er, with my father's handloads for .280 Rem. Since they were for a Remington 760 and the standard .280 and not the AI version, I had considered them safe to shoot through the custom mauser. However, I believe that there is either an issue with the rifle, loads, or both.

From the beginning, the brass exhibited pressure signs. The primers were flattened, and in one case, the primer pocket blew out completely on the same load and there was noticeable trouble lifting the bolt (unsurprising), after which we quit shooting.

Now, the kicker that has me looking for help is that I suspect that there may be a headspace issue. The case heads are noticeably belled towards the rim of the case, narrowed uniformly like they'd been constricted during firing. This is mostly noticeable to the touch and not to the naked eye, but it's there, along with a slight colour change in the brass.

Should I have the gun headspaced, or just try for much lower pressure loads?

In addition, I'm curious as to my options if the gun DOES have excessive headspace. It has already been turned down from a .280 Rem, would the barrel be able to take being turned down a thread again, or should I look for a new barrel?

 

[hunter5425]

Using other's handloads is problematic, for example the cases could be sized to fit fit easily in a tight chamber ie min spec and yours could be a loose chamber ie max spec causing apparent headspace issues when the issue is the ammunition and not the chamber. Try some factory ammunition and see what happens.

 

[reb]

Fire form the cases in your rifle then load them and you should be fine.

 

[rral22]

Fire form the cases in your rifle then load them and you should be fine.

I agree. I would never try to diagnose a problem while fire forming from one set of dimensions to another. If the loads chamber easily, shoot them. Reload and then see if there are issues.

 

[hawk-i]

Probably best to pull the bullets...reduce the load...reseat the bullets to contact the lands and Fireform.

 

[Ganderite]

^^^ Seat bullets hard into the rifling.

 

[stubblejumper]

Probably best to pull the bullets...reduce the load...reseat the bullets to contact the lands and Fireform.

Good advice.

 

[bearhunter]

^^^ Seat bullets hard into the rifling.

This is what I do as well.

OP, of course you have a headspace issue with cases that are to short. Ganderites suggestion is the easiest way to keep the base of the cartridge against the bolt face and allow the shoulder to form forward.

When you're shooting your father's handloads, the whole case is trying to expand in all directions and the firing pin has pushed the case forward, OFF the bolt face. That's why you're experiencing blown out primers. If the base of the cartridge is held back against the bolt face, the primer has to stay in the pocket all the way.

I've seen it happen where full power cases don't fully fire form because of this.

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[struff55]

Bear hunter has the correct answer . The only correct answer spend some money and buy 280AI brass and avoid such problems . The 280 AI works with 3-4 gr more powder than the 280 sp reducing the charge will not change anything . Actulay there is one more corrrct answer if you want to use 280 brass you will have to load your own loads with a minimum charg listed in a manual then seat the bullets so they are touching the rifling in your rifle .doing so will not allow the case to travel forward in the chamber and the brass will expand properly

 

[remington jim]

Throw the SH*T away and just use Proper head stamped 280 AI brass and you wont be on here with a problem ! jmo RJ

 

[leonk05]

nothing wrong with fire forming 280 into AI chamber. Thats the whole point of the cartridge. Issue lies elsewhere.

 

[remington jim]

nothing wrong with fire forming 280 into AI chamber. Thats the whole point of the cartridge. Issue lies elsewhere.

No Point in it thou - theres LOTs of 280 AI brass avail now with the CORRECT headstamp ! MUCH cheaper then wasting Bullets -Primers & Powder fire forming ! Fire forming Makes NO sense with this cartridge ! jmo RJ

 

[bubba300]

You say it is a mauser,are you feeding your bullets threw the magazine or are you chambering them.The old controled actions need to be fed thew the mag I believe.

 

[remington jim]

I Feed my 280 AI s in my custom Husky 1600 either way with no problem ! RJ

 

[tiriaq]

This is a gunsmith built rifle.
Who knows how the chamber was cut? A standard procedure when cutting an AI chamber is to use the standard GO gauge to set the chamber depth - the GO gauge is felt when the bolt is closed. A factory cartridge should just contact the chamber at the neck/shoulder junction, and will be held in place for the first firing.
Reloads previously fired in a different rifle? Not a good starting point.
Ready made AI brass might or might not fit the custom chamber properly. No reason to assume that it will.
Setting the bullet into the rifling can hold the casehead back and avoid headspace problems for first firing. Creating a false shoulder can work too. Expand a new .280 case to .30, then resize most of the neck back to .280, leaving enough of a shoulder to hold the case firmly in place.