Looking for Canadian sources for chamber reamers.

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Sasquatch807

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Hi guys,

I was asked to chamber a rifle in .280 AI but Brownell's is out of reamers for this caliber and ordering from the the manufacturers (Clymer, Manson and JGS) will take very long due to the Covid crisis.

Does anyone know of a Canadian retailer or source for these?

Thanks for any help.
 
Unless I'm reading it wrong, isn't the standard shorter headspace?
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The AI versions have a headspace 4 thou shorter than the standard version. Ackley did this so you would fire form cases with very little stretch if any. A standard go gauge becomes a no go gauge for the AI version. It is why a barrel chambered for the standard cartridge needs to be set back when chambering to the AI version.

In reality if you can not feel the bolt close fairly firmly on a standard case you are about to fire form to the AI version, you will end up with a weakened case with a shorter lifespan.
 
Ok, that all makes sense, I understand.
But for my own knowledge, on the SAAMI drawing it shows the improved headspace reference to be slightly longer, why is that?
I have a 257 Ackley built on a VZ24 by Jennings in Winnipeg about 30 years ago, and I get good case life.
Sorry for derailing the thread.
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Your looking at the wrong numbers for the headspacing. You want the ones where the neck and shoulder meet not the shoulder and body.
 
If I remember correctly where you measure on the shoulder is where a 3/8" ring would make contact... for 06 based cases.

I leave it up to the manufacturers to produce correct steel go and no go gauges...
 
guntech said:
If I remember correctly where you measure on the shoulder is where a 3/8" ring would make contact... for 06 based cases.

I leave it up to the manufacturers to produce correct steel go and no go gauges...
Click to expand...

I make my own gauges AND reamers. I like to live dangerously. And I'm a cheapskate Finn working only on my own guns.
 
mudpro said:
Your looking at the wrong numbers for the headspacing. You want the ones where the neck and shoulder meet not the shoulder and body.
Click to expand...

If you look at the drawing there is a measurement noted with an x in a circle. If you then read the the legend it tells you this measurement is the headspace reference, gives minimum and maximum headspace measurements.
 
kawicrash said:
If you look at the drawing there is a measurement noted with an x in a circle. If you then read the the legend it tells you this measurement is the headspace reference, gives minimum and maximum headspace measurements.
Click to expand...

Yes, but if you chamber the standard case in the Ackley chamber, does it contact at the datum line? No it doesn't, only at the neck to shoulder junction. So that is the standard-cartridge-to-Ackley-chamber headspace.
 
The confusion with Acklley cartridges is Ackley's fault. Chamber length is measured from the bolt face to the chamber shoulder with a gauge of the same shoulder angle. Simple enough, however Ackley decided to change the chamber shoulder angle without making proper fitting gauges to match. As the shoulder angles of the gauge and chamber are no longer identical the gauge now only makes contact at the neck/shoulder junction. This new dimension is designed to be typically .004" shorter than the parent case/chamber to support the case for fire-forming. Now that the chamber is .004" shorter the bolt will not close on the "GO" gauge. Therefore the "GO" gauge becomes the "NO-GO" and a new "IMPROVED GO" is required which is simply a "GO" that is ground .004" short. As archaic and inferior as this sounds it worked back in Ackleys day when not much thought was put into neck diameters. Obviously a change in chamber neck diameter will change the location of the neck shoulder junction and now the gauges are wrong again.
 
I think Ackley did just fine and with safety in mind. This so called "confusion" isn't his fault. I believe from day one he was clear on the procedure for chambering "improved" rimless cartridges but I am sure many barrels have been chambered incorrectly... due to insufficient knowledge on the individual doing the work.

It's the same when reloading and pushing the shoulder way back...and wondering why there are case separations... insufficient knowledge, you see it all the time.
 
Only on one cartridge did Ackley make a real error; that was on the 30/06 AI. On that one he did list the 30/06 datum minus .004 which meant that the juncture of the neck and shoulder is off by about .030". All of the other cartridges are based on the distance to the juncture of the neck/shoulder. This measurement varies considerably because of tolerances which allow some variation in shoulder angle and neck diameter. This is why one can chamber to minus .004 on the gauge and still end up with significant head clearance on the cartridge and why some brands of ammunition might fit perfectly while others might be a bit loose. For these reasons, being sure the customer understood how the improved chamber and headspacing worked was semi-critical to the outcome. I frequently chambered AI's to fit the brass being used rather than using the gauge just to ensure a good interference fit. It took Nosler months to come up with a headspace measurement for the 280AI just for this reason, there is a wide variation in the distance to the neck/shoulder.
JGS was thinking of trying to establish measurements to an established datum for all of the AI cartridges but, ultimately, decided it was a can of worms best left alone. Even the 30/06 AI, with the obvious error, they are reluctant to change.
 
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