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I have been shooting 223R 80gr Sierra MKs and have now changed to the higher BC 80gr Amax projectiles. I shoot long range and the higher BC bullets are an advantage.
When seating these bullets for a 6 thou jump the same as I used for the Sierras they seat much deeper into the case. The OAL measured with a Hornady comparator is 2.940" for the Amax and 2.970" with the Sierra.
The Amax is a longer bullet than the Sierra and seating them for a 6 thou jump resulted in some load compression. It appears the bullets seat deep into the case neck. I would prefer a chamber that allowed only the bearing surface of the bullet seated into the neck and not any deeper.
Has anyone had a reamer made specifically to suit the 80gr Amax bullet and could give details of what they used.
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I have got the info I needed from Dave at PT&G and I have ordered a 223R reamer with .085" free bore. This should allow more room for powder and have only the boat tail sitting down thru the neck into the shoulder of the case.
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Thunder: I have the same problem with the 80 AMax in a MacLennon barrel with a Wylde .223 chamber. The specs say the Wylde has a longer leade but when I seat the AMax bullet I can feel the front of the boattail going through the donut which means it has to come back through the donut on firing. MacLennon could not guarentee that he could line up the axis of a throating reamer with the axis of the Wylde reamer so he wouldn`t extend the leade. Honest on his part. But I have a Toronto `smith lined up who feels he can perform the operation. Too late for the Ontario and Canadian Prize Meets but over the next Winter I plan to do the deed.
Good luck down under to a Commonwealth compadre.
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Hi 1000ys, I bet its a pretty common issue when changing projectiles to the longer Amax.
I did some checking and the Wylde reamer most likely has a .0619" leade (freebore). The PT&G Match reamer has .068" freebore and I have ordered one with .085" which should do what I want nicely.
I got the info on 223R reamer dimensions from http://www.ar15barrels.com/data/223-556.pdf I hope you get yours sorted out for the Amax projectiles as a bit more BC never goes astray!