Die machining?

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cbh560

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I have a full length die for my 7mm-08AI that doesn't seem to be quite right. After resizing my fireformed brass through FL die, it would seem that my brass is growing by 3-4 thousandths of an inch. This stretch in length then makes the resized die very hard to chamber. I can close the bolt, but with a good amount of effort.

I think what is happening is that the die is too long and is fairly tight, causing brass to flow towards the shoulder when resizing. I can cam-over the press against the die and it's not enough to bump the shoulder back enough to allow proper chambering. Do I have any options other than taking the die to a machine shop and having them remove 10-20 thousandths from the face of the die? I'm thinking to have 10-20 thousandths removed because I don't know exactly how much the shoulder needs to be bumped. If I remove more, I can adjust the die in the press to accomodate.

Thoughts?
 
Cheaper yet, see how thick a feeler gauge you can slide in the shell holder under (below) the case head. Often there is .005 to .010 room there. Then try sizing a case or two to see if that solves the problem - the feeler gauge in place essentially pushes the case a bit further into the die than without. Cam over, etc. sounds all good. Cheap way to verify if that is the problem without any permanent alterations. From your description, I'll bet you need less than .005, maybe only .003 to get that bolt to close easily.
 
The shoulder angle could be different between your die and your chamber. The die would likely be right and the reamer used to cut the chamber be wrong due to resharpening or something. Brass fired in your rifle should always fit back in your rifle. Compare a fired piece to a resized one. Something else you could do is only neck size the brass and see how that works.
 
The simplest and cheapest thing to do is lap the top of the shell holder after making sure you do not have a defective shell holder with the wrong deck height.

Below a fat chamber and a skinny die will cause the case to "grow" more in length when sized. Also pausing at the top of the ram stroke for 4 to 5 seconds reduces brass spring back,

wm05ArY.gif


The proper height is .125

k8hyF40.jpg
 
Potashminer said:
Cheaper yet, see how thick a feeler gauge you can slide in the shell holder under (below) the case head. Often there is .005 to .010 room there. Then try sizing a case or two to see if that solves the problem - the feeler gauge in place essentially pushes the case a bit further into the die than without. Cam over, etc. sounds all good. Cheap way to verify if that is the problem without any permanent alterations. From your description, I'll bet you need less than .005, maybe only .003 to get that bolt to close easily.
Click to expand...

Good suggestion. I will pick up a set of feeler gauges to check this.

billdick said:
The shoulder angle could be different between your die and your chamber. The die would likely be right and the reamer used to cut the chamber be wrong due to resharpening or something. Brass fired in your rifle should always fit back in your rifle. Compare a fired piece to a resized one. Something else you could do is only neck size the brass and see how that works.
Click to expand...

Shoulder angle seems to match up very well. When I chamber the brass with some sharpie on it, the shoulder seems to have good contact from the neck to the case body. Fired brass fits better than resized. No hard chambering.
 
Since the brass is currently fireformed? why not use a neck die only and trim your brass rather than working the case so much. I have taken material off dies to correct problems as well, but i thought this question might be pertinent.
 
Got Juice? said:
Since the brass is currently fireformed? why not use a neck die only and trim your brass rather than working the case so much. I have taken material off dies to correct problems as well, but i thought this question might be pertinent.
Click to expand...

Mostly because I don't have a neck die for the 7-08 AI, but if I did I can really only get a few loads before you have to full length size anyways. At some point it needs to be dealt with.
 
bigedp51 said:
The simplest and cheapest thing to do is lap the top of the shell holder after making sure you do not have a defective shell holder with the wrong deck height.

Below a fat chamber and a skinny die will cause the case to "grow" more in length when sized. Also pausing at the top of the ram stroke for 4 to 5 seconds reduces brass spring back,

wm05ArY.gif


The proper height is .125

k8hyF40.jpg
Click to expand...

Well that dimension measures exactly 0.125" on my shell holder.
 
Potashminer said:
Cheaper yet, see how thick a feeler gauge you can slide in the shell holder under (below) the case head. Often there is .005 to .010 room there. Then try sizing a case or two to see if that solves the problem - the feeler gauge in place essentially pushes the case a bit further into the die than without. Cam over, etc. sounds all good. Cheap way to verify if that is the problem without any permanent alterations. From your description, I'll bet you need less than .005, maybe only .003 to get that bolt to close easily.
Click to expand...
Tried the feeler gauge. There is only 0.003" of wiggle room there. And that requires wiggling the brass just right to get it in there.
 
And is that enough?? If you can close the bolt, but it feels tight, you are only needing a "smidgeon" more! Maybe you have another shell holder to try (like 308 Win, 30-06, 8x57, 7x57, 243Win, etc.)? The difference between Go gauge and NoGo gauge is often only .004 or .005 so you are really close as is. Maybe even a .002 feeler might be enough. Let us know!
 
Potashminer said:
And is that enough?? If you can close the bolt, but it feels tight, you are only needing a "smidgeon" more! Maybe you have another shell holder to try (like 308 Win, 30-06, 8x57, 7x57, 243Win, etc.)? The difference between Go gauge and NoGo gauge is often only .004 or .005 so you are really close as is. Maybe even a .002 feeler might be enough. Let us know!
Click to expand...
Ive actually got two of the same shell holder and tried them both.
I'm not sure. My gauges are just a bit too wide to actually fit completely into the shell holder under the case. I can only fit it at an angle into the mouth of the shell holder and slip a case in over top. I would need to cut up my gauges to really tell.
 
You can neck size with full length dies by threading the die out of the press a turn or two. I have some AI firearms that I only neck size for and have fired the brass six or more times. The best thing with the AI cartridges is that the shoulder is so steep that the brass never needs trimming.
 
bigedp51 said:
The simplest and cheapest thing to do is lap the top of the shell holder after making sure you do not have a defective shell holder with the wrong deck height.

Below a fat chamber and a skinny die will cause the case to "grow" more in length when sized. Also pausing at the top of the ram stroke for 4 to 5 seconds reduces brass spring back,

wm05ArY.gif


The proper height is .125

k8hyF40.jpg
Click to expand...
Since I happened to have a duplicate of this shell holder I tried what you suggested. I took it down 0.012", testing a piece of brass in 0.002" increments as I went. Now I have easy chambering with no resistance. I would say that I now have 0.001" to 0.002" bump on the shoulder. Seems odd that the die would be out by 0.010". For interest sake, they are CH4D dies.

Appears as if the issue is fixed, I just have a dedicate shell holder to that set of dies.
 
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