Will a 280ai reamer clean up a 7x57ai chamber?

[troy fairweather]

Was thinking of reaming my 7x57ai out to 280ai. Looking online and can't find a reliable chart for the 7x57ai reamer spec, I have a 280ai reamer but it's up at my dads so I can't do anything yet. Just want to be sure it fully cleans it up.

the 7x57 would be fine but has a cut on the shoulder in the chamber, it does not hurt the brass but it shows on the brass, the other thing is the neck is tight. Factory ammo will not chamber, brass needs to be about .010 but no thicker. I would get a outside neck turned for the brass but that's not in my budget right now.

 

[SGW Gunsmith]

It sounds like a reasonable plan that could most likely be done by hand reaming. All you want to do is cut the shoulder a bit deeper, correct? The Ackley reamers only have around 1° of body taper and the shoulder angles are pretty much the same, so, your plan just might work.
I would give Pacific Tool & Gage a call and speak with a technician concerning your plan, if only to verify what you'd like to accomplish. I think there's even a place whereby you can rent a reamer rather than buy one. Let us know how your plan works out.

 

[troy fairweather]

It sounds like a reasonable plan that could most likely be done by hand reaming. All you want to do is cut the shoulder a bit deeper, correct? The Ackley reamers only have around 1° of body taper and the shoulder angles are pretty much the same, so, your plan just might work.
I would give Pacific Tool & Gage a call and speak with a technician concerning your plan, if only to verify what you'd like to accomplish. I think there's even a place whereby you can rent a reamer rather than buy one. Let us know how your plan works out.

The case taper is what is worrying me, I don't want to end up with a chamber with to body tapers. I have a 280ai up at my dads to use, so I don't have to buy/rent one.

I figure if I cleaned up the shoulder it would be a wildcat so I kind as well fully chamber it to 280ai anyways. I will make a chamber cast to get a better measurement of my chamber.

 

[fguffey]

Artifacts, some 280 Remington's started life as a 7mm57, problem, the military 7mm57 has a larger diameter neck resulting in a two diameter neck on the 280 Remington chamber.

F. Guffey

 

[troy fairweather]

Artifacts, some 280 Remington's started life as a 7mm57, problem, the military 7mm57 has a larger diameter neck resulting in a two diameter neck on the 280 Remington chamber.

F. Guffey

My chamber neck is about .314 or .315 think all the 280ai are about that size to.

 

[fguffey]

I thought about helping with the chamber cast but typing got so slow I lost interest.

F. Guffey

 

[SGW Gunsmith]

The case taper is what is worrying me, I don't want to end up with a chamber with to body tapers. I have a 280ai up at my dads to use, so I don't have to buy/rent one.

I figure if I cleaned up the shoulder it would be a wildcat so I kind as well fully chamber it to 280ai anyways. I will make a chamber cast to get a better measurement of my chamber.

You're way ahead of the curve. I was going to suggest a chamber cast to verify what you have now. Then, you can compare the shoulder angle to that of the reamer. Too bad you don't have an "optical comparator" to work with...............or do you?
Troy, that picture of the cartridge case above. The shoulder angle looks as though it has not been completely formed, so that alone may lend a bunch of credibility to your plan to finish with the .280 Ackley Improved reamer. Looks more like a Weatherby case. Would be nice to have a gauge or spent case to check progress on how the bolt closes.

 

[troy fairweather]

You're way ahead of the curve. I was going to suggest a chamber cast to verify what you have now. Then, you can compare the shoulder angle to that of the reamer. Too bad you don't have an "optical comparator" to work with...............or do you?

Nope no comparator, I took a little risk on trying for did the right neck. Sounds bubba sit looks to worked out.

I took a old Lee case trimmer pilot that was broken, rapped with wet dry paper, that opened the neck up to about .315, then did the same with fine paper. Came out about .316 the chamber cast looks good neck looks perfect. All factory 7x57 now chamber good. The headspace on the factory ammo seams a bit tight, the last bit off the bolt closing you feel tightness. There is also a shinny spot around the shoulder.

I'll have to fire some rounds and see how it works out. I figured since I was going to ream it I couldn't hurt to much trying to in large the neck some.

I made a cast, but only about 1 inch of the chamber I can't find the rest of the casting metal. The reamer is up at my dads so I will have to wait till I go back up by him.