300 WM resize

[rinodods]

First time I've run into this one. New barrel with new brass. Using Norma and Nosler. First firing feeds fine. Granted it's slightly under spec. After first firing bolt is slightly stiff. Just barely above normal effort. Not running a really hot load here. Only 76gr H1000 under a 215 berger. I do however have very light ejector marks on the brass. Bolt close after firing is of course increased. The problem is when resizing I've do the die completely maxed and if I'm lucky I get a .002 shoulder bump in my RCBS full length S type bushing die. Case is still stiff to close the bolt on and the second firing has come seriously sticky bolt. I've measured out the fired brass and according to SAAMI specs there is nothing wrong here. It's spot on in every respect but no matter how much I size (tried a second lee die I had as well) I can't get what I would call normal resistance on closing bolt. I recheck headspace and everything is tight there. I'm not seeing much if any growth in the brass as evidenced by only being able to barely bump the shoulder. Is it possible I just have a really tight chamber here and my SAAMI spec dies can't give me quite what I need to get things back in shape? What are the options? Maybe send in a case and have a die made to match the chamber?

 

[MagnumManiac]

Are you sure you are adjusting the die down enough?
Just having the die in contact with the shell holder WITHOUT a case installed in the press is NOT FL sizing, or even close to it. The shoulder moves forward when the brass is sized, then you must adjust your die until a case chambers with slight resistance, then with some head clearance.
Are you camming over?
If not, adjust your die for full contact with the shell holder, then screw it IN 1/16-1/8 turn, size a case as you normally would, clean it, try to chamber it, if stiff, repeat until the bolt 'just' closes with some resistance, then another 1/32 turn IN will give you around .002"-.003" head clearance.
For more precise adjustment use 1/16 turns, and disassemble your firing pin from the bolt, or if it has a 3 position safety, use the middle setting, it takes the firing pin spring pressure off the bolt lugs.

Hope this helps.

Cheers.
gun)

 

[rinodods]

Oh I wish it was a simple die setup problem. I suspected the same thing because even after years of reloading and my 3rd 300WM a guy can still screw up. My Lee press doesn't cam over but rest assured the ram is fully stopping on the die and then some. I even thinned the shell holder off a few thousandths to try and get just a little more movement. No dice. Used this same set of dies on my previous barrel and it was fine. Had plenty of adjustment left to get this type of thing sorted out and I had them adjusted just as you described. Sort of a positive feel on bolt close but not stiff. Can't even get close to that this time. For the life of me with the cases not measuring way out of normal I can't come up with anything but the chamber being a little on the tight side. This isn't exactly a bad thing unless you have an elk hunt in three weeks. The loads look awesome gettting 3030fps average and an SD of 8. Don't think I'm really going to hurt anything unless I get a case stuck but that would really stink in the field. Might have to fall back to my 300WSM. Which I'm not afraid to do. The gun shoots every bit as good. Just really wanted the 300WM out this year. If you can think of anything else please pipe up. I'm not afraid to admit a brain fart. gun)

 

[MagnumManiac]

It does sound like you have a minimum chamber, this poses a problem, but I have a simple and easy temporary fix for you. Get yourself a set of automotive feeler gauges, try the .005" gauge first, slide it under the case and hold it in place with your left hand (if right handed.) and size the case, try to chamber it, if still stiff try the .008" gauge, if the .010" gauge doesn't fix it, you can go to the .015" gauge in steps, but I wouldn't go more than that.
I have encountered this several times over the years, once you determine what size shim works, you can turn the same amount off the TOP of a shell holder and keep that with that die set. I have a few cartridges like that myself right now.

Let me know how you go.

Cheers.
gun)

 

[brentc]

First time I've run into this one. New barrel with new brass. Using Norma and Nosler. First firing feeds fine. Granted it's slightly under spec. After first firing bolt is slightly stiff. Just barely above normal effort. Not running a really hot load here. Only 76gr H1000 under a 215 berger. I do however have very light ejector marks on the brass. Bolt close after firing is of course increased. The problem is when resizing I've do the die completely maxed and if I'm lucky I get a .002 shoulder bump in my RCBS full length S type bushing die. Case is still stiff to close the bolt on and the second firing has come seriously sticky bolt. I've measured out the fired brass and according to SAAMI specs there is nothing wrong here. It's spot on in every respect but no matter how much I size (tried a second lee die I had as well) I can't get what I would call normal resistance on closing bolt. I recheck headspace and everything is tight there. I'm not seeing much if any growth in the brass as evidenced by only being able to barely bump the shoulder. Is it possible I just have a really tight chamber here and my SAAMI spec dies can't give me quite what I need to get things back in shape? What are the options? Maybe send in a case and have a die made to match the chamber?

Are you sure you're body sizing your brass during the shoulder bump?

 

[rinodods]

Are you sure you're body sizing your brass during the shoulder bump?

Don't see how I couldn't be. During sizing the shell holder is actually making full contact with the bottom of the die. It couldn't size any more. I'm getting almost .002 in shoulder bump there but the case still are difficult to chamber. Like I said I did the same routine with an older Lee die I had with the same results. Basically no shoulder movement and a lot of resistance on chambering. I think some of my cases are gonna go in to Whidden Gunworks for a custom full length bushing die. They say 10-12 weeks now to get it done. Thought about getting a small base die and trying that but I'd likely push the shoulder way back there before I got the sizing I needed lower on the case. All part of the fun I guess. It a new McGowen barrel and so far everything I've feed it has been very consistent. Just think the chamber is a little tight and my load is getting close to max. I'll back it down on the next attempt and see if I can get rib of some of the issue but long run it appears I'm gonna need a die closer to may chamber spec. gun)

 

[dkhunt14]

When brass is new it is more forgiving. If you are getting ejector marks on the first or second firing you are too hot. Sometimes dies can be wrong. I have seen dies vary on the amount they size the case. You can take off the shell holder and get more bump. How are you measuring the bump? Maybe your press is springing under pressure and not letting you get what you need. It wouldn't take much spring to make a couple thousandths. Your chamber is probably on the minimum headspace. Matt

 

[rinodods]

When brass is new it is more forgiving. If you are getting ejector marks on the first or second firing you are too hot. Sometimes dies can be wrong. I have seen dies vary on the amount they size the case. You can take off the shell holder and get more bump. How are you measuring the bump? Maybe your press is springing under pressure and not letting you get what you need. It wouldn't take much spring to make a couple thousandths. Your chamber is probably on the minimum headspace. Matt

I actually have a bump gage to measure how far I'm bumping the shoulder. I'm using a Lee classic cast press. The ram is in the middle of an open D shape. I'm sure that isn't flexing. I've used both dies I've tried on a couple other 300WM chambers and they were fine. Never had this trouble in those so I'd hope it isn't the die sets. I will for sure back off some the next load. The marks are pretty faint and the primers aren't flat but if I look close I can just barely see the round ejector marks. The more I look and check and measure the more I go back to just having a load on the max side and something close to a minimum spec chamber. You guys are have some good ideas on what to look for though and I do appreciate the help. Really hoped there was some stupid thing I was missing. I'll mess with it a little more here in a few minutes and take a look at the stuff you pointed out just in case.

 

[rinodods]

Here is a quick pic of a case after I marked it up and ran the bolt down on it several times. Looks like it rubs just below the shoulder and just above the belt and this is after running the case until the shell holder is hitting the bottom of the die with 0.020 of shim between the case head and shell holder.

 

[MagnumManiac]

Here is a quick pic of a case after I marked it up and ran the bolt down on it several times. Looks like it rubs just below the shoulder and just above the belt and this is after running the case until the shell holder is hitting the bottom of the die with 0.020 of shim between the case head and shell holder.

I can plainly see your chamber is short, there is contact on the front edge of the belt, take it back to whoever built/chambered the rifle. If the headspace to the belt doesn't measure .220", you'll never get the shoulder to case head measurement correct.

Cheers.
gun)

 

[rinodods]

I can plainly see your chamber is short, there is contact on the front edge of the belt, take it back to whoever built/chambered the rifle. If the headspace to the belt doesn't measure .220", you'll never get the shoulder to case head measurement correct.

Cheers.
gun)

Not saying this isn't correct but its a belted magnum. It headspaces on the belt. Wouldn't you expect some contact? Maybe I'm just thinking about it the wrong way. It happens.

 

[MagnumManiac]

Yes, it headspaces on the belt, but that is why it's called head...........space, there must be some wiggle room. If the belt is hard up against the chamber, you won't be able to size it back because the belt is solid, it cannot change in dimension.
I may be wrong, but it looks to me that your chamber is too short in the headspace.
If a .020" shim didn't fix the issue, I would be taking it back to whoever chambered the barrel.

Cheers.
gun)

 

[rinodods]

Yes, it headspaces on the belt, but that is why it's called head...........space, there must be some wiggle room. If the belt is hard up against the chamber, you won't be able to size it back because the belt is solid, it cannot change in dimension.
I may be wrong, but it looks to me that your chamber is too short in the headspace.
If a .020" shim didn't fix the issue, I would be taking it back to whoever chambered the barrel.

Cheers.
gun)

That helps a little. I really do appreciate the input. I wouldn't probably have spotted it. I was kind of leaving out the shoulder to belt bit in sizing. Of course if the belt is stopped hard against the chamber then I'll have issues in sizing with standard dies. Just sucks the thing shoots so well. I hate to touch it. I suppose I could live with the chamber being on the short side. It isn't bad enough to reject factory brass. Can't think of any real danger here. Just can't size right now like I should. Just for grins if I left the chamber as is and just had a die made off some fired brass would I really be missing out on anything?

 

[MagnumManiac]

Probably not, but you must realise that brass will expand to the point where it needs to be reduced in size to chamber, maybe you could try a Redding body die and see what happens, they're reasonably cheap in the US.
The problem is that you can't physically alter the belt to head dimension, but you could try different brands of brass until one feels right and sizes enough to fit.
Cheers.
gun)