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Old February 23, 2002, 11:19 AM   #1
Shawn H
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Join Date: February 21, 2002
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.308 problems

Thanks to all who take time out of their day to provide insight. My problems are as follows:

My friend and I worked up a load for his Remington 742 (autoloader) in .308.
Using RCBS die set we loaded 165 gr. Nosler BT into new Winchester brass. Finished it off with a Lee Taper Crimp Die (Not Factory Crimp), which actually crushed a case at the shoulder when adjusted as the instructions indicated. So we backed out the die a bit until we had satisfactory results. We then hand cycled the rounds through his rifle to check for bullet-setback. Well, there was no setback, but there was setforward! Initial OAL was 2.805. After cycling the round it was 2.811, and a second cycling brought it to 2.819. The same thing happened with three other rounds. There were scratches on the case and bullet, perhaps from the magazine lips.
Any suggestions? I am at a loss to explain this, as I was expecting bullet setback if anything. I am uneasy about the bullet moving at all, and cannot adjust for anymore crimp, as the case buckles. I am not too concerned, but I am curious as to how the bullet is being moved forward.
Thanks to all,
Shawn
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Old February 23, 2002, 01:01 PM   #2
Paul B.
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Shawn. It's called inertia, An object in motion tends to stay in motion. The brass case stops because the extractor hold it in place, but the bullet which is not held quite tight enough by the crimp moves forward. You might take the expander button out of the die and polish it down a couple of thousandths of an inch. That should help alleviate the probblem.
Another thought is you may still be crimping a bit too much and the neck opens up a hair so that only the front of the neck is holding the bullet. It would be easier to explain that one if I could draw a picture, but you could try backing off a hair on the crimp to see if that fixes it.
Paul B.
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Old February 23, 2002, 01:08 PM   #3
swifter...
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I've seen this before with autoloaders. When the action chambers, the sudden stop of the round "pulls" the bullet slightly, just like an inertia bullet puller.
Unless you're running some King-Hell on the edge load, and if the amount of pull seems pretty consistant, I'd be inclined to go ahead and shoot 'em to see if this is a peoblem or not as far as accuracy goes. In that rifle, accuracy isn't likely to be benchrest grade anyway...
The solution may be to increase bullet pull, by sizing the case neck smaller, rather than crimping.
You also might try measuring some factory rounds before and after, I wouldn't be surprised to find that they move a bit, too. I think all autoloaders do this to one extent or the other.
Hope this helps, and please post your results.
Tom
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Old February 23, 2002, 04:19 PM   #4
Fatelvis
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Shawn, I think Paul B. is on the right track. I would cut back on the crimping, or even try a couple with no crimp at all. Also, clean your expander (on your sizer) to make sure there is no buildup of lube, crud, whatever, that could open up the neck a little too much. I would mike the bullets` diameter, and make sure they`re not undersized, (factory defects do make it out to the public!) And if all that doesnt work, chuck your expander/depriming stem into a drill, and polish off a .001'', or a little more, to increase the neck tension on the bullet. I`ve done it to a 22 Hornet, that used .223" dia. bullets, and it works well. - Good luck, let us know how it works!
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Old February 23, 2002, 07:57 PM   #5
Shawn H
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Join Date: February 21, 2002
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Thanks guys, I will clean my expander and try less crimp on the next batch. We'll go ahead and shoot these to see what kind of accuracy the ol' Remington can produce. Tom's right, this rifle probably won't give anyting near MOA accuracy, but my friend did hit a deer silhouette at 380 yards the first time he tried (surprising both of us beyond comprehension), using factory Remington Cor-lokts at that!! I believe he hit it in the arse, but it was still impressive.
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