300win mag problem

fireball · #1 03-05-2009, 09:42 AM

I have two 300 win mag rifles. One full sizes ok and the other doesnot. If I full size according to book, the cases seperate after one reload, and they hard to chmber. So, I had to back off the full length resizer to the point that the case neck has only about 1/8" to hold the bullet. NOT ENOUGH. I was wondering what else to do?

sbtennex · #2 03-05-2009, 11:00 AM

If you're F/L resizing and they're hard to chamber in the same rifle they were shot out of, sounds like excess lateral expansion, the width of the case near the web is expanding too much. A small base die should fix it.
You really shouldn't need to or want to F/L resize a belted case - first time you shoot them they're fireformed to that chamber and either partial sizing with a F/L resize die or simply using a neck resize die should be plenty. Fast case separation is a combination of way too much work stressing the cases by F/L resizing and an overgenerous chamber, maybe compounded by too warm a load. You want to resize a belted mag case to headspace off the shoulder, not the belt. I partial size - adjust the F/L die to size pretty well all of the neck, as the .300 has a short neck to begin with, and if the die touches the shoulder at all it's only the slightest bump. Try a clean fired case, if it's not too long overall, that came from that rifle - it should rechamber. I think you're overworking the brass, way overworking it, moving too much brass around with your F/L resize die. Headspacing off the belt (F/L resizing) in some belted cartridge chambers can theoretically still allow for easily 10 thou of linear expansion and still be within man'f specs for the chamber - the stretch has to occur somewhere, and in the case of the .300 Mag it'll be just ahead of the web area, thinning and weakening it very quickly. Result is a case separation. The two chambers are different - never get the brass mixed up. Keep them separate and resize just enough to give you a good neck grip, at least 2/3 of the neck is being resized - pull the decapper stem and set the die carefully, starting at about 3/4 of a turn back out from touching the shell holder then adjusting just enough down in very small adjustments to ensure a smooth feed (on one case only) in the chamber it came out of. Once the die is set and locked set put the stem back in and do them all. The exception to all this is if you have a semi or a levergun, in which case F/L is probably your only resize choice anyway.
This is basically my way - you'll hear others I'm sure, but I can get 7 - 10 reloads out of my .300 brass, pretty warm loads, without much thinning or excess stretching. I do, however, anneal them after 3 then again at 6. Had one, once, that failed on the first resize attempt. It cracked, but that had to be a flaw as it was a factory shell fired only once.
Other thing that comes to mind is make damned good and sure your resizing die is clean inside, spotless, no lube , dust or general grunge buildup.

fireball · #3 03-06-2009, 10:05 AM

Thanks for getting back to me so quick. I will try everything.
Also, in the Dec2008 Alberta Outdoorsman mag(p57) it had an article on the
Belted Magnum Collet Die by Innovative Technoligies. Would this help and where could I get one??
Thanks again

elkhunter11 · #4 03-06-2009, 10:13 AM

Are you keeping the brass from each rifle separate,or are you mixing the brass and using it in either rifle? The best practise is to keep the brass separated,and keep using the same brass in the same rifle.

sbtennex · #5 03-06-2009, 11:17 AM

Quote:

Originally Posted by fireball

Thanks for getting back to me so quick. I will try everything.
Also, in the Dec2008 Alberta Outdoorsman mag(p57) it had an article on the
Belted Magnum Collet Die by Innovative Technoligies. Would this help and where could I get one??
Thanks again

Never had any reason to try this die - working brass is working brass, that simple. A Lee deluxe set includes a collet type neck sizing die as well as a F/L and a "dead center" bullet seater and they work fine. All the same, as posted earlier if conventional partial sizing to just maintain enough neck tension still won't allow the brass to be rechambered in the rifle it came from, then the small base is the answer. Remember reading about the IT die a while back, and the one thing I seem to remember was the price. Theory of it seemed sound enough, but stretching and separation aren't a problem since we started headspacing off the shoulder. More reloading manuals should be pointing this out - a couple do, but not all. Maybe it's time to go back and reread the blurb about IT's die......

eric2381 · #6 03-06-2009, 12:15 PM

The Lee collet neck sizing die is a wonderful thing. Try it out, I doubt you'll be disapointed. Good luck, Eric

fireball · #7 03-08-2009, 04:42 PM

Quote:

Originally Posted by sbtennex

Never had any reason to try this die - working brass is working brass, that simple. A Lee deluxe set includes a collet type neck sizing die as well as a F/L and a "dead center" bullet seater and they work fine. All the same, as posted earlier if conventional partial sizing to just maintain enough neck tension still won't allow the brass to be rechambered in the rifle it came from, then the small base is the answer. Remember reading about the IT die a while back, and the one thing I seem to remember was the price. Theory of it seemed sound enough, but stretching and separation aren't a problem since we started headspacing off the shoulder. More reloading manuals should be pointing this out - a couple do, but not all. Maybe it's time to go back and reread the blurb about IT's die......

Thanks again, but another ?? What is this small base you mentioned?

sbtennex · #8 03-08-2009, 07:18 PM

Quote:

Originally Posted by fireball

Thanks again, but another ?? What is this small base you mentioned?

A small base die for resizing is just a F/L die that's been built and reamed to the minimum SAAMI spec size. Most die man'fs make them in common calibers, but it's usually only needed in some semis, pumps and leverguns. I've only seen this problem once in a Ruger bolt rifle and it was a .300 Mag as well. Solution was to start fresh with new brass, F/L size it and fireform with a good load. After that the brass only needed partial, just enough for enough neck grip, sizing to fit just fine, whereas the old brass simply wouldn't rechamber. Leads back to the probability that the fired brass was switched between your rifles somehow (hey, it happens - a lot easier than it should). The chambers are obviously quite differently sized in the two rifles, not uncommon at all, especially in the belted Mags. Where your brass separated at the web, the thickness can be measured with a bit of a particular tool. If you're not a competition shooter going thru piles of .300 ammo, it's probably cheapest to start fresh, new brass, like we did....

catnthehat · #9 03-08-2009, 08:24 PM

Quote:

Originally Posted by fireball

I have two 300 win mag rifles. One full sizes ok and the other doesnot. If I full size according to book, the cases seperate after one reload, and they hard to chmber. So, I had to back off the full length resizer to the point that the case neck has only about 1/8" to hold the bullet. NOT ENOUGH. I was wondering what else to do?

Lee FL die by any chance?
sullijr and I had a similar problem a few years back with a friends 300 mag, and also with his 7mag using Lee FL dies.
The dies would not size down the brass after they were shot from the
SAME RIFLE!!

A switch to my RCBS FL dies fixed everything.
A particular die sometimes will be made a bit larger than is spec'd by SAAMI, often because of worn tooling.
I would try borrow some RCBS or other brand of dies and try them out - never can hurt!
Cat

209x50 · #10 03-08-2009, 10:14 PM

Quote:

Originally Posted by fireball

Thanks for getting back to me so quick. I will try everything.
Also, in the Dec2008 Alberta Outdoorsman mag(p57) it had an article on the
Belted Magnum Collet Die by Innovative Technoligies. Would this help and where could I get one??
Thanks again

You can find the collet die at:
Collet Die

sbtennex · #11 03-09-2009, 02:02 PM

The one issue with this we had came up using an RCBS F/L die, so I wouldn't be blaming a die brand, even if it were a Lee.
Fireball: I assumed (should know better) that you're checking the case length after resizing and trimming to 10 thou or so under max, right???? If they're too long the problem's probably a lot easier to fix...

catnthehat · #12 03-09-2009, 03:21 PM

Quote:

Originally Posted by sbtennex

The one issue with this we had came up using an RCBS F/L die, so I wouldn't be blaming a die brand, even if it were a Lee.
Fireball: I assumed (should know better) that you're checking the case length after resizing and trimming to 10 thou or so under max, right???? If they're too long the problem's probably a lot easier to fix...

I'm not insinuatiing that Lee builds bad dies, but I have seen three issues like that.
Sometimes a die change is all that os needed.
It may be because they sell so many that the tooling needs to be reoplaced more oftne that others, I dunno.

Also with WSM cases we often had to grind down Lee shell holder a few thou. to get them to FL size.
FWIW, I use more lee dies than any other brand....
Cat

sbtennex · #13 03-10-2009, 11:27 AM

Quote:

Originally Posted by catnthehat

FWIW, I use more lee dies than any other brand....
Cat

X2. I actually really like their Deluxe sets and for the 3-die levergun stuff their dies are as good as anybody's. I didn't even bother changing the O-rings to a locking collar - they seem to stay pretty well where you leave them. Nice finish on their stuff and real interesting to take apart - have to admire the engineering they put into some of their simple tools......