Best depth to seat a 75-80 Amax BT bullet in the case neck?

V

VaniB

New member
I am going to assemble two dummy cartridges for Dave at Pacific to base my new 22x47 Lapua rifle chamber. I intend to try and use 75 & 80 Grain Hornady Amax bullets exclusively.

This is my first custom chamber, and I'm not sure what the optimum placement of the bullet should be inside the case neck.

BOTH THESE BULLETS HAVE LONG BOAT TAILS slightly over 1/8" long. (aprox 5/32")

THE QUESTION:
Should I make dummy cartridges with the entire boat tail end of the bullet below the neck shoulder joint and resting in the powder section of the case? ....and should compressed loads be a concern?
 
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I assume that your .22x47 is a necked down 6.5x47, but it doesn't really matter what the case is, the throat of your chamber will tell you where the bullets will be seated at. You can't seat the bullet any farther out than touching (or jamming) the rifling, and assuming that the rifle is a single shot or will be used as a single shot you won't have to worry about feeding through a magazine. If the rounds will be fed from a magazine they'll have to be seated deeply enough to feed.

With heavy bullets seated to magazine length in an AR in the .223/5.56x45 the base of the bullet is well into the case body. Not optimal theoretically probably, but it works and its where the bullet has to be.
 
There is currently no chamber. I need to have one made. Dave will proceed to make a chamber around the dummy round I provide for him. The cartridge is to be fed through a Rem 700 magazine, and a 22x47L is well within the Remington SA.

I'm thinking that the entire base of the boat tail should be below the joint where the neck starts (and into the powder portion of the case.) But, I just need to hear from others that this is correct.
 
The more bullet shank in the neck the better if you're feeding from the magazine, but I'd willing to bet that Dave Kiff will be able to give you as good or better opinion on this than just about anyone else. Either him or someone at Hornady. They won't charge for their advice, and it's from the people who are likely to know best.
 
When I built my wildcats, I seat so that the bullet boattail/body junction is right at the case neck/shoulder junction.

This puts as much of the bullet bearing surface held by the case neck without intruding into the powder capacity that much.

With such a large case, you will not need to worry about powder compression.

Unless you really feel the need to go fast, I feel the 22-6BR or 22-6 Dasher is plenty big to get those Amax over 3300fps.

Some have run them faster but I think there is a higher chance they won't fly accurately.

I am presently pushing 80gr Amax out to a mile with a 223 and they are doing just fine. Going another 600fps would be nice but a huge waste of time if the bullets don't make the trip.

Jerry
 
Thanks Jerry. As you seem to be suggesting, I had supposed too that as long as the case wasn't a compressed load, the entire boat tail butt of the bullet sticking in the case shoulder would not be a problem.

As an off topic about cartridge choice: The two problems I had with considering the 22BR or the 22 Dasher, was that neither could be depended to feed easily through the magazine of a Rem 700. I was also not too crazy about the required fire forming of the Dasher. Though I always feed cartridges one at a time into my Rem chambers, I still don't like non-working magazines in a rifle. If my rifle has a magazine, then I want it to work. This is just my personal schtik I guess.

I hear that their are gunsmiths who can make one or both of these cartridges feed in a 700 reliably. But, they are not the smith I use.

So then, the 22x47L was just an easier choice to go with. It accepts superior pressure to easilly fire the 75 & 80 grain bullets, and I should not have to case turn.
 
If you neck down 6.5X47L brass to 22cal, you will need to neck turn otherwise you will be dealing with necks over 18thou - too much.

If you want simple, the 22/250 is boring but will do all you want.

Want more gas, 22.250AI and just fire 22/250 brass while fireforming. Next to no case prep.

The case capacity of the 22/250AI is way over what you will need to get those Amax to 'puff' velocity.

I sincerely doubt you will enjoy the mega pressures the Lapua case can deliver.

Win cases will be plenty tough enough to handle the magnum pressures that you are unlikely to meet.

YMMV.

Jerry
 
It's always fun to discuss cartridges with you or anyone else...but......

I have 100 new 6.5x47 Lapua cases, Forster dies, and Redding 22x47L "Custom" dies sitting on my desk, and a $400 Visa bill to match.

I think I'm past the cartridge deciding phase of this project.
 
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