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300 Win Mag brass swelling under the belt

Old Dude

Private
Minuteman
May 12, 2018
60
50
I have a Remington 700 that is brand new. I loaded 100 rounds for it using H1000 and 208 ELDX's. Started light at 72 and went up in .5 grain increments. I didnt check speeds but I did check for group size. 5 round groups. 75.5 was my tightest at just under 3/4 center to center. At 78.5 I had a heavy bolt lift with a slight cratering so I did not shoot those or anything past. Here's my problem. Using redding dies. When I use new brass the case slide's right into the die. When I try to resize my once fired I find that it has swollen from new brass at .505 under the belt to .512. It is swollen all the way to the neck. No matter how much I clean the die and polish the brass. No amount of lube will let me get a case to fully enter the die. I would have to put so much weight on the handle that it would tweek my loading table. I've loaded for 30-06 and 300 Savage with out any trouble. Could my chamber be that off? This is a factory barreled action that I bought new. What am I doing wrong.
 
No 300WM die will resize a case back to factory spec. The die will resize the case so it will chamber, that’s it.
 
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Outers. The table is plenty strong for the new brass. I mean I really tried to press it in with out slamming it. I have to slap the handle a few time pretty hard to get the case to release from the die. I spent the time reading the reloading threads stickys on here and dont see what I am doing wrong. My 06 was a breeze with the same equipment. RCBS Rock Chucker with Redding dies. And the new brass just slid in and out slicker than snot on a greased doorknob. Same lube, same procedures.
 
It will chamber. What it wont do is tighten the case mouth back to what it needs to be. The bullets are a easy slip fit right now.
 
your first post claimed the case wouldn't fit inside the die for a full resize... now they fit all the way in but the neck isn't being sized? Are you using a Redding Body die? We still need to know what lube you're using....
 
Sorry No the case fits the rifle easily but not the die. I'm using Outers gun oil. Thats what the guy at the store said to use. I have the redding two die set. I am having a problem with the decapping / resizing die. I had to run the decapping pin out to remove the primers.
 
Use a proper resizing case lube. Outer gun oil is NOT a case lube. That's your first problem. Sounds like you need some help. Is there anyone near you that is an experienced reloader that can give you a hand ? There'a a major malfunction here that needs to be looked at. Those dies should work fine.
 
Use Redding imperial sizing was as lube.

^THIS!!!

A friend that reloaded 300wm for hunting claimed his brass was finished after one or two firings. I told him to bring it to me. He bet me a beer I couldn't size it. Eventually he brought some over I dabbed my finger on the Imperial wiped the case and sized it easily in a redding body die. He was dumbfounded and short the cost of an IPA at our local pub.
 
LOL I live in CA. No one admits they do anything with guns. I think we do have a guy who reloads a lot of ammo. I will try him tomorrow too. I need to find a good gun smith in the Orange county area if anyone has a recommendation. I have found out I am just a powder filler. Not a reloader.
 
You’ve got the right attitude to become a “reloader” lol

Some good calipers to take good measurements the whole way. See what it was before and what it was after. It’s the easy way instead of blindly guessing. Yes it takes time but it takes more time to not figure it out the easy way.
2465009C-BE98-4C57-B43D-9D359E43F936.jpeg

I don’t really care what the virgin is other than a nice factoid to know, I want to know what the fired (chamber size) is compared to the sized out of the die. I agree that much base sizing seems like a lot but if thats from virgin it’s sort of moot for what’s happening going forward with regard to the chamber-die relationship.


And then some good lube. Hornady one shot, imperial, lee, Dillon, lanolin home brew, basically anything that’s marketed as an actual “case” lube for case sizing should at least suffice. If it’s wet going on let it dry for 20 minutes as the nonlube fluids aren’t lube-y.
 
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I have Mics and calipers. I was really worried about the .007 increase at the belt. I will buy some real lube tomorrow and get back to here with some info. Thanks for taking the time to help.
 
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Then, after you have used a proper sizing lube, and figured out some of the other nuances to reloading, and are now on your 5th or 6th or more firing of that 300WM brass, you will want to purchase one of these.
 
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@Old Dude, which Redding sizing die are you using? Is it a Standard sizing die or a Bushing sizing die?
In post #5 you said the neck isn't getting sized. It's a long shot, and may come off as a stupid question, so I'll apologize in advance, no offense intended -- is it possible you have a Bushing sizing die, but no bushing installed? If you do have a bushing please tell us what size it is.
 
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I have Mics and calipers. I was really worried about the .007 increase at the belt. I will buy some real lube tomorrow and get back to here with some info. Thanks for taking the time to help.
My 338 win mag cases grow to 0.512 just above the belt too, certainly after a couple of firings... I use a Redding Body Die to size them without any problems.... As mentioned, I also use a Belted Magnun Collet resizing die by Innovative Technologies to take the 0.512" down to 0.510"-0.511"... Chambering is perfect when I tighten up that dimension.... Imperial Sizing Die Wax works better than all the Witch pisses I've tried.... Your chamber may vary, but you're on the right route to mastering your Belted Magnum resizing regiment...
 
@Old Dude,

It should be mentioned that even with the IT die in the video, the case can still thin right above the belt on the inside. A technique to check this is to straighten a paper clip and put a small bend on one end. Slide this through the case mouth and drag it along the inside of the case. If you feel a groove the case may be close to separation. I think several reloading manuals mention this.
 
Here is the solution



I use this die as part of my belted mag reloading process. Works great! I also use Royal Purple as my lube for all my reloading. You just have to swipe your die with a cleaning patch every so often to avoid buildup which can dent the cases.
 
Thank you to all of you for your help. I purchased some RCBS Case Slick. First I swabbed out my dies with alcohol. Then wiped down my brass. after lubing the die and case It slid right in without any problems. Now to measure what it sizes it back to.
 
LOL I live in CA. No one admits they do anything with guns. I think we do have a guy who reloads a lot of ammo. I will try him tomorrow too. I need to find a good gun smith in the Orange county area if anyone has a recommendation. I have found out I am just a powder filler. Not a reloader.

I hear ya, I'm kinna on the down low about my gun stuff too, and I'm in the mid-south, but Damn! what kinna upside down country are we living in, that we fear reprisals for a completely LEGAL Hobby / obsession, While BLM, Antifa rioters / looters fear not?
 
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OK Measurments. Unfired brass at belt. .505, fired brass is .512. resized brass is now .510. Neck ID new is .305, resized is .304. . I just cant thank you all enough for your help. Now i'm off to load 100 rounds and shoot next week out to 300 yds. I havent shot that far since I was in the Corps. Present load is 75.5 grains of H1000 with CCI magnum primers, and a 208 Grain Hornady ELDX set .015 back of the lands. I single feed because it's too long for my magazine by a bunch. I am using an AI chassis with AI mags. OAL is 3.651.
 
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Thank you to all of you for your help. I purchased some RCBS Case Slick. First I swabbed out my dies with alcohol. Then wiped down my brass. after lubing the die and case It slid right in without any problems. Now to measure what it sizes it back to.
It always slides in with a little lube :)
 
No I dont yet. All I do right now is to take a unprimed case, slip in a bullet and chamber it. From that overall reading of 3.671 I am pulling it back to 3.651 for a .020 jump. I have a good set of calipers and a 1 inch mic. but thats all as far as measuring tools go. To me it seems like I have a deep throated chamber. Since Sammi spec is 3.340 for overall. I'm sure that might be because I am using such a much more pointed and streamlined bullet. My guess is the lands are touching way farther back on a 208 ELDX than a 150 or 168 round nose lead tipped hunting round.
 
No I dont yet. All I do right now is to take a unprimed case, slip in a bullet and chamber it. From that overall reading of 3.671 I am pulling it back to 3.651 for a .020 jump. I have a good set of calipers and a 1 inch mic. but thats all as far as measuring tools go. To me it seems like I have a deep throated chamber. Since Sammi spec is 3.340 for overall. I'm sure that might be because I am using such a much more pointed and streamlined bullet. My guess is the lands are touching way farther back on a 208 ELDX than a 150 or 168 round nose lead tipped hunting round.
You’re describing how far your bullets are jumping to the lands. He was asking how much the brass shoulders were sized back towards the case head.
 
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The 300wm and other belted cases actually headspace off of the belt, but when you resize a fired case you want to bump the shoulder back just .002. Some may refer to this as changing the head spacing to the shoulder from the belt.
With a .002 bump you are giving the case less room to stretch therefore extending case life.
 
I understand the shoulder bump. I can only use dry erase on the shell and see where it is touching when I chamber it. I dont think I have a way to measure the shoulder setback with what I have. All I can be sure of is that so far the case shows a sign of being touched by both the belt and the shoulder. Not exactly sure of how to push the shoulder back if the belt is being contacted also.
 
Measure a fired case with the headspace comparator. Back the die out from the shell holder with the ram all the way up. Measure it again and then turn the die in slightly. Repeat until you have .002 shoulder bump.
 
Measure a fired case with the headspace comparator. Back the die out from the shell holder with the ram all the way up. Measure it again and then turn the die in slightly. Repeat until you have .002 shoulder bump.
I have one in my cart at Amazon. Got a possible health issue to deal with then it’s mine.