Confused as usual; .243 AI head space gauge

Apologies if I’ve taken any good natured badgering wrong. It is hard to tell a person’s tone on forums.
 
Mram10 said:
Easy trig could find you a new datum point that would work with both cartridges, however, saami uses .375 as the datum and that is the published, accepted chambering spec. If you want to do it differently than saami, more power to you, but don’t tell people they are wrong for doing it the saami way. Good luck in court if something happens to a customer’s rifle and you didn’t use saami specs. I prefer to use accepted saami specs. Using saami specs, the answer to the op’s question is “the headspace is farther from the base on the ackley then is is on the parent case.”

I read your link a couple times and see how the nose on the parent gauge would hit since the shoulder/neck junction is shorter for the ackley. In the instance of a 243 ackley, the accepted method is measuring from base to .400” and it should be about .035” longer than a parent 243.

Been fun gentlemen. I need to hit the chamber with some 80grit ao paper to get the scratches out. Not sure why the reamer leaves scratches ..... I’m holding the drill true....
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The measuring method for the shoulder is a steel ball of specified diameter (after measuring its diameter) that is dropped into the chamber (barrel pointed down obviously).

There are a number of methods to then measure bolt face to rear of the ball.

I use 'sliding gauges' that have a plug that slides into a cut off piece of brass.
The same sort of trick used to measure the distance to the start of riling for a particular bullet.

Since bolt action riles can apply a decent amount of force you can make the plug inside the shell a tighter fit.
Make sure the plug can move far enough into the case.
I ream the inside of the case to make sure it is a uniform diameter for enough distance back to allow the plug to enter.

Since the rod is only going to touch the steel ball in the chamber you can use steel instead of brass.

I turn a plug that is a snug fit inside the reamed case but has a reduced diameter front that will touch the steel ball and nothing else.
And has a truly flat front surface.

Insert the plug, close the bolt, remove the plug gently.
Measure the length carefully.
Remove the steel ball and measure the diameter again.

Add the two measurements.

The actual headspace dimension of that chamber is what you have.
 
Whatever works for ya. It is very easy to machine your own gauges so I guess that’s what I’m used to.

What size bearing would you use for an ackley? Thanks
 
Mram10 said:
My argument : use the datum and headspace length on the saami specs, cause it is approved.
Does that make sense to you now???

I was walking away peacefully and you hit my in the back with a proverbial snowball :)
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SAAMI is a way of making sure that ammunition made by ANYONE will fit and function safely in a rifle made by ANYONE.

Many AI rounds have NO SAAMI spec.
They are essentially 'wildcats.'

If you are using a gun chambered in one of these cartridges it is up to YOU to make sure the ammunition you build will work safely in THAT rifle.

This means you may need to make a chamber case to measure things from.

Ackley specified a 'standard procedure' to follow in making a gun chambered in an AI cartridge.
When carefully followed it results in a case with increased powder capacity and (typically) a
sharper shoulder for less 'case growth' on repeated loadings and firings.

The .220 Swift has a well earned reputation for 'case growth.'
Frequent trimming is required.

A .22-250 AI gives comparable performance.
With far less 'case growth' from the sharper shoulder.

And both burn barrels very nicely.
Stainless lasts slightly longer but the leade will get burned with either.
You can chase it with bullet seating for a little while, but a setback and rechambering is in the future.

Make sure you leave enough metal on the barrel shank in front of the chamber.
And the odds of the brass you have fired fitting in the new chamber is often not all that high.

I have dedicated barrels with damaged throats and some accuracy loss to shorter ranges for a while,
then set them back fare enough to get a fresh leade.

A lot depends on if you are doing the work or paying someone to do the work.
I do a lot of my own work so the cost is mostly time since I buy my own reamers anyway.
Even if I have someone else do the work.
 
I didn't take the time to read through all these posts on the .280 Ackley. My 2 cents and worth about that much. I had a .280 Ackley reamer and go gage a long time before Nosler came out with their .280 Ackley brass and had it made into a SAAMI cartridge. I'd read all this about the difference between the old .280 Ackley and the new .280 Ackley. So, since most guys were using the Nosler brass, I ordered a new .280 Ackley go gage so that I would be using the correct go gage to work with the new brass. I'd read all the differences in the SAAMI specs opposed to what the reamer prints were showing. I did a little test and reamed a chamber gage cutting just the shoulder, neck and throat into the gage. Dropped it over the old go gage and measured from the base of the gage to the top of the chamber gage. Then did the same thing with the new Ackley go gage. Both go gages measured identical. I quit worrying about the supposed difference between the Nosler specs and the old specs. Turned out according to these two gages, that there wasn't any difference. I chambered a .250 Savage Ackley Improved on Monday. The bolt just closes on the Ackley go gage and the bolt just barely starts to close with the standard .250 Savage go gage.
 
Mike Bryant said:
I didn't take the time to read through all these posts on the .280 Ackley. My 2 cents and worth about that much. I had a .280 Ackley reamer and go gage a long time before Nosler came out with their .280 Ackley brass and had it made into a SAAMI cartridge. I'd read all this about the difference between the old .280 Ackley and the new .280 Ackley. So, since most guys were using the Nosler brass, I ordered a new .280 Ackley go gage so that I would be using the correct go gage to work with the new brass. I'd read all the differences in the SAAMI specs opposed to what the reamer prints were showing. I did a little test and reamed a chamber gage cutting just the shoulder, neck and throat into the gage. Dropped it over the old go gage and measured from the base of the gage to the top of the chamber gage. Then did the same thing with the new Ackley go gage. Both go gages measured identical. I quit worrying about the supposed difference between the Nosler specs and the old specs. Turned out according to these two gages, that there wasn't any difference. I chambered a .250 Savage Ackley Improved on Monday. The bolt just closes on the Ackley go gage and the bolt just barely starts to close with the standard .250 Savage go gage.
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Thank you Mike! But you're likely about to be berated with nonsense from people who have never done this test but believe that what they read on the Internet is the gospel, because big names in the industry mean they're perfect and you and I...Well, we musta got lucky or something to make our claims actually work with different gages
 
Any ackley other than the 280 is fair game to use the old ways. In today’s age of liability and with the 280 having a saami spec, IMO, it is wise to use those measurements.

It all started when someone said to a new guy that the headspace is shorter on an ackley than the parent, which according to the only comparison the new person can find is a 280, thus confusing them because it is the opposite. Just a difference in measuring from approved datum vs shoulder/neck junction. Then the snotty comments by some making a guy that uses the datum way(saami) out to be an idiot, made this a bit heated.

I don’t mind disagreeing but the “do you even build guns” comments from some is off base. I’ve built 3 7-08 ackleys in the last month. I do understand headspace
 
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mwezell said:
Thank you Mike! But you're likely about to be berated with nonsense from people who have never done this test but believe that what they read on the Internet is the gospel, because big names in the industry mean they're perfect and you and I...Well, we musta got lucky or something to make our claims actually work with different gages
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You can't ever tell when you get a go gage, what you are getting. I just looked at my .280 Ackley go gages. One is dated 8-01 and the newer one is dated 4-12. The gage marked 4-12 has a 40 degree shoulder while the other one has the standard shoulder. They both measured the same with the chamber gage cut with the 40 degree shoulder. I've looked at SAAMI prints for the .280 Ackley and reamer prints from the manufacturer. The numbers between the two prints don't appear to jive to me. But, in practice, I haven't seen that it makes a difference. I'm not much of an Ackley fan although I have most of the Ackley reamers. I'll take a case that doesn't change much from the initial case shape on its first firing as fire forming cases is wasted rounds down a barrel. A PPC is about my only exception and I have a dedicated fire forming barrel for fire forming them.
 
I took a basic load of 37g Varget with 168 vlds in 308 brass that I neck sized to fit tight in the chamber. They shot pretty darn well for fireforming rounds. Pleasure to shoot with a muzzlebrake. Zero kick and easy to see hits.

First ackley I built, I tried to load 41-42 gr Varget with 168s and separated a few cases. Learned real quick to use 7-08 data when fireforming.
 
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