Shoulder bumping-HELP

[Stavi300RUM]

I shoot a 300 ultra mag that I'm starting to have troubles with. I had a smith do some stuff to it and develop a good load for it. I've followed his load recipe for THIS rifle with exactness. Lately it's been giving me troubles with extraction. I never looked at shoulder bumping and wonder if this is the issue. I got a Hornady headspace/"should bump gauge" and have been measuring cases. They are all over the place. I use Redding dies, so I figured they'd be spot on.
Question now...how does a guy measure them accurately when there is that little ring around the primer sticking up? I understand that between .001-.002 is the happy spot from what I've read and so I want to deprime the case without sizing it so it can be measured correctly.
Any advice would be great. If someone is in the Idaho Falls area, I'd be more than happy to come over and be shown a thing or two.

 

[MagnumManiac]

What you need to do is to buy yourself a universal decapping die, RCBS sell them.
The other thing you need to do is to get your firing pin hole in your bolt face looked at.
If this rifle is a Rem 700, most likely cause of your primers cratering, is from a bevel in the firing pin hole. Have seen heaps of rifles from Remington like this, including my own, which I bushed to fix the problem.
When you say problem extracting, exactly what is happening, hard bolt lift, extractor slipping over the rim leaving the case in the chamber, or something else?

Cheers.
gun)

 

[Stavi300RUM]

What you need to do is to buy yourself a universal decapping die, RCBS sell them.
The other thing you need to do is to get your firing pin hole in your bolt face looked at.
If this rifle is a Rem 700, most likely cause of your primers cratering, is from a bevel in the firing pin hole. Have seen heaps of rifles from Remington like this, including my own, which I bushed to fix the problem.
When you say problem extracting, exactly what is happening, hard bolt lift, extractor slipping over the rim leaving the case in the chamber, or something else?

Cheers.
gun)

It is a hard bolt lift, but only on a couple. Most extract fine, but the ones that give trouble result in me hitting the bolt up and back with the side of my palm. When inspecting those cases there is definite pressure signs.
Ill have to get that RCBS die and get to work on them.

 

[Rich Coyle]

Stavi300RUM,

It is a hard bolt lift, but only on a couple. Most extract fine, but the ones that give trouble result in me hitting the bolt up and back with the side of my palm. When inspecting those cases there is definite pressure signs.
Ill have to get that RCBS die and get to work on them.

It sure seems like you have too much powder. When a shoulder needs to be bumped back you have trouble closing the bolt. Second on the universal deprimer.

 

[rcoody]

I shoot a 300 ultra mag that I'm starting to have troubles with. I had a smith do some stuff to it and develop a good load for it. I've followed his load recipe for THIS rifle with exactness. Lately it's been giving me troubles with extraction. I never looked at shoulder bumping and wonder if this is the issue. I got a Hornady headspace/"should bump gauge" and have been measuring cases. They are all over the place. I use Redding dies, so I figured they'd be spot on.
Question now...how does a guy measure them accurately when there is that little ring around the primer sticking up? I understand that between .001-.002 is the happy spot from what I've read and so I want to deprime the case without sizing it so it can be measured correctly.
Any advice would be great. If someone is in the Idaho Falls area, I'd be more than happy to come over and be shown a thing or two.

lots of things to check

trim length?

neck sizing or full length resizing?

How many firings?

do you anneal

 

[cowboy]

lots of things to check

trim length?

neck sizing or full length resizing?

How many firings?

do you anneal

Different/hotter lot of powder?
Did you switch brand of primers by chance?
Ambient temps now versus before?
Carbon/copper build up?

I would run your load through a chronograph to see what kind of velocity you are producing. Would be even better if you knew where you were at before extraction problems started.

Whatever it is - I would not think that shoulder bump is the cause if your loaded rounds feed well with an easy bolt close.

 

[Stavi300RUM]

lots of things to check

trim length?

neck sizing or full length resizing?

How many firings?

do you anneal

Cases are trimmed to length. I full length resize. On my 3rd firing, but I don't anneal. I know the concept, but don't know really how to set a system up for it.

 

[rcoody]

Cases are trimmed to length. I full length resize. On my 3rd firing, but I don't anneal. I know the concept, but don't know really how to set a system up for it.

3rd firing and full length resizing work hardening should not be a problem

and you have not changed any of your procedures or components?

how many rounds through the rifle?

 

[Stavi300RUM]

Different/hotter lot of powder?
Did you switch brand of primers by chance?
Ambient temps now versus before?
Carbon/copper build up?

I would run your load through a chronograph to see what kind of velocity you are producing. Would be even better if you knew where you were at before extraction problems started.

Whatever it is - I would not think that shoulder bump is the cause if your loaded rounds feed well with an easy bolt close.

From what I understood, the lots are the same. I'll have to play a little with it and run some loads over a chrono. Thanks for the input!

 

[BountyHunter]

Firing pin is not causing the hard bolt lift. If everything else is OK switching to a harder primer can fix that many times.

The primer flowing around the pin is a sign of high pressure.

3rd full power firing you would be getting max expansion on the case. Measure unfired and fired about .250 above extractor rim to see difference. Especially key on brass hard to extract. Chances are here is your problem.

Then check resized brass and see how much sizing you are getting.

 

[Stavi300RUM]

Firing pin is not causing the hard bolt lift. If everything else is OK switching to a harder primer can fix that many times.

The primer flowing around the pin is a sign of high pressure.

3rd full power firing you would be getting max expansion on the case. Measure unfired and fired about .250 above extractor rim to see difference. Especially key on brass hard to extract. Chances are here is your problem.

Then check resized brass and see how much sizing you are getting.

I'll definitely give that a look. Right now I'm using CCI 250 primers. Federal match 215 are a bit hard to find.
Pressure sign is just very slight, so you're probably right. I'll inspect those cases prett close to see if they're spent.

 

[HammerB1]

Primers still tight on the ones that are hard to extract?
It's sounding like to much pressure. Remington Brass?
I've had Remington brass do the same thing my ultra mag. I had to get rid of brass that was causing the issues. What I realized was the brass did not have the same powder capacity.
I've had same issue with the 257 Roberts brass.
Brian

 

[Stavi300RUM]

Primers still tight on the ones that are hard to extract?
It's sounding like to much pressure. Remington Brass?
I've had Remington brass do the same thing my ultra mag. I had to get rid of brass that was causing the issues. What I realized was the brass did not have the same powder capacity.
I've had same issue with the 257 Roberts brass.
Brian

The pockets are still pretty tight. I'm shooting Nosler brass cause it's the only I can find at the moment. I may have to just toss the brass that stuck. Hate to do it, but not worth chancing it.

 

[HammerB1]

I've tossed all of my Rem and Nosler brass in the 300 RUM and have gone to Norma. It seems to be much more consistant and stronger.
Brian