Ot 243.

[Ackman]

Originally Posted by Chickenthief

If i remember correctly AI chambers are ever so slightly longer than standard and that tyny bit might cause a headspace like "problem".

You remember incorrectly. Since you really don't know, why bother.

[trotterlg]

Regardless if the round is loaded or empty, the primer will still force the case forward to the shoulder and the primer back against the bolt face, the only difference is that a loaded round will then force the case back against the bolt head which will try to re-seat the primer. Most of the time the primer doesn't re-seat completely and ends up being really flattened out with the profile of a Mushroom if you look at one from the side. In any event, the excess headspace is there no matter what the cause. Larry

[Bayou City Boy]

Originally Posted by trotterlg

Regardless if the round is loaded or empty, the primer will still force the case forward to the shoulder and the primer back against the bolt face, the only difference is that a loaded round will then force the case back against the bolt head which will try to re-seat the primer. Most of the time the primer doesn't re-seat completely and ends up being really flattened out with the profile of a Mushroom if you look at one from the side. In any event, the excess headspace is there no matter what the cause. Larry

I'm not arguing with you about actual issues with kenbro's rifle, but none of this is absolute when firing primers only. Results vary with brass hardness, neck thickness, primer pocket depth ( even too much) and a bunch of other issues that only cloud the real answer. Bottom line is kenbro needs to buy his gunsmith some proper AI gauges if he's going to chamber rifles and be considered competent in doing so.

That's the bottom line. The rest is just conjecture, or in other terms a Semi-educated WAG.

-BCB

[trotterlg]

All I am saying is that there is no reason that I can think of that firing a primer only will be different than firing a loaded cartridge in the chamber (unless you have loaded it so that the bullet is jammed into the lands) so the head space you measure that way will be the same with a loaded or unloaded case. The case will stretch the amount of the headspace to fill the chamber if a loaded round and the primer will back out to fill the chamber with an empty. Larry

[SShooterZ]

FWIW I've seen Superperformance ammo both back out and pierce primers in different .223 rifles. And an AR. They load them too hot for some guns IMO.

[georgeld]

Surely someone here has a properly chambered .243AI.
How about posting a picture of one?

A bit OT but, similar. This .358U/m I just built. The cases after necked out
shrink quite a bit in length from standard .300U/M. don't know if that would relate to Ken's problem or not.

I haven't measured them but, they're obvious when side by side.

[Daryl]

Originally Posted by SShooterZ

FWIW I've seen Superperformance ammo both back out and pierce primers in different .223 rifles. And an AR. They load them too hot for some guns IMO.

With many ctgs. it is entirely possible to get excessive pressures in one while another gives sub-par ballistics - same ammo - same ctg.

One other such ctg. is the .270 Winchester, but only with 130gr. factory ammo, it seems.

1 (one) rifle out of 5 in a test produced 3,140fps from factory WW. 130gr. ST's and another only 2,720fps- same make of ammo, same lot # and same test by the same guy. All the guns had 22" bls. The other 3 rifles, produced speeds between those extremes. With 150gr. they were all within 50 or 60fps. Go figure.

Ed Matunas was the tester and addressed these extreme vel. differences in a test while developing/writing up a loading manual.

The ammo companies he contacted due to those discrepancies in his data, told him the worse ammo for attempting to get reliable ballistics out of was the .270Win, but with only 130gr. ammo. 150gr. ballistics were stable in a wide variety of rifles.

We all now by now, different guns behave differently with the same ammo. I think what isn't realized, is the huge difference there can be between individual guns.

Safe in one gun and excessive in another - entirely possible, especially when working with very high pressures.

When ammo is loaded to an average of 65,000PSI and another 2 thousand PSI blows primers even in THAT gun, there will or can be be problems.

An example - I once had a .30/06 Rem Model30 that showed pressure signs with Speer's manual's maximum 165gr. loads & H4831 as well as IMR 4831 loads, grossly flattened and cratered primers with stiff extraction, yet they produced 220fps under what Speer indicated they received for a 24" bl., same length as my barrel. My barrel mic'd at .308.

I rechambered that SLOW barrel to .300 Win. Mag. and all of a sudden it was a 3,365fps rifle with 165's (200fps faster than Speer's listings for that ctg.) and no pressure signs - rounded primers and little finger lift on the bolt. Loved that ctg., but - it would no longer shoot 180's or 190's, my favourite for moose at 2,650fps in handloads.

Guns are different, period - some surprise us in a bad way.

[georgeld]

Daryl:
Guns just have to be female!
Can't be any other reason for the differences between two alike.

That's exactly the reason the loading books stress to start low and increase while watching the results: guns are different.

Side note: fellow in Tx sent 50 cast RN .360", I powder coated them last night and resized back to .360". Going to start with 90gr 7828 and compare to same wt jackets. You ever try powder coating cast? Me either.

[Daryl]

No powder coating - yet.

[kenbro]

Just an update
Over two weeks since gunsmith said regular .243Win gauges were right for chambering 243AI chambers, but, he would check with David Manson, just to be sure. Then he would come back to me.
He must have forgotten. ��