Shoulder bump

[wheelgun7360]

Need some help with my Defiance 7mm br IHMSA silhouette gun. Been using factory Rem 7 br brass. This gun shoots lights out. Been shooting it since I had it built in 2010. Was at a big match last year in North Carolina and had problems chambering it. 5 out of 10 would not chamber. I always full length size with a redding bushing die. Went to match last weekend and 2 out of the first 5 would not chamber. Same load same brass that I started with. You think the die is not bumping the shoulder correctly. I need some help on how to bump the shoulder back a couple .000. What tools do I need to check it and how? Thanks Allen

 

[SET]

I would think the same brass you've been using for 8 years might have something to do with it.

 

[LHSmith]

Yes, old brass tends to cause problems.
This might help:

http://forum.accurateshooter.com/threads/shoulder-bump-question.3918495/
and cycle every loaded round through the action BEFORE the match -with firing pin removed.

 

[wheelgun7360]

The brass has only been fired 4 or 5 times so I think it should be ok. I guess an order from Sinclair is in my future. Thanks guys for the help. Allen

 

[243winxb]

A hornady comparator to measure.

Will the brass chamber, after sizing, before loading it.

When sizing, have the shell holder contact the bottom* of the die when sizing.

edit spelling*

 

[wheelgun7360]

A hornady comparator to measure.

Will the brass chamber, after sizing, before loading it.

When sizing, have the shell holder contact the botton of the die when sizing.

Most of the brass will chamber but a few will not. I will get a comparator to check the shoulder bump. Thanks Allen

 

[LHSmith]

Most of the brass will chamber but a few will not. I will get a comparator to check the shoulder bump. Thanks Allen

Also mic the case diameter just above the extraction groove and compare to those that chamber and those that don't.

 

[johnfred1965]

If you have an empty 9mm case, you can use that as a quick and dirty comparator. put it over the neck of the case and measure before sizing. Resize the case and measure again. The difference, if there is one, is how far you "bumped" the shoulder. Have you been trimming back the necks as well? Your cases may have stretched a bit in 4-5 firings. Just a thought.

 

[Dusty Stevens]

I've tested several different times when fitting some shell holders. My experience shows no difference if the shell holder contacts or not. Care to share your thoughts/experiences?

A properly fit die will bump the case the proper amount before the die contacts the shellholder. Check the fit in your chamber dont go by those die instructions

 

[fguffey]

Same load same brass that I started with. You think the die is not bumping the shoulder correctly.

There is not one shooter on this forum that can answer your question, there is not one shooter on this forum or any other forum that can bump the shoulder back. All of them are repeating what they read on the internet, I can only guess they have no investigative skill or curiosity. Back when I started there was no one telling me 'this is how it is done'.

I can shorten a case from the shoulder to the case head, I can not shorten the case from the shoulder to the case head by moving the shoulder back. And then; again, it is impossible to bump/move the shoulder back with a die that has case body support.

If you are having trouble sizing cases I suggest you lower the die to increase the presses ability to overcome the cases ability to resist sizing. There are stories about shooters that have friends that have friends that have shot cases 45+ times; not a one of the shooters can tell me how much the case weighed when they started and when they finished. And, the stories are embellished with claims the friend of a friend did all of that with max. loads.

F. Guffey

 

[6MMsteve]

There is not one shooter on this forum that can answer your question, there is not one shooter on this forum or any other forum that can bump the shoulder back. All of them are repeating what they read on the internet, I can only guess they have no investigative skill or curiosity. Back when I started there was no one telling me 'this is how it is done'.

I can shorten a case from the shoulder to the case head, I can not shorten the case from the shoulder to the case head by moving the shoulder back. And then; again, it is impossible to bump/move the shoulder back with a die that has case body support.

If you are having trouble sizing cases I suggest you lower the die to increase the presses ability to overcome the cases ability to resist sizing. There are stories about shooters that have friends that have friends that have shot cases 45+ times; not a one of the shooters can tell me how much the case weighed when they started and when they finished. And, the stories are embellished with claims the friend of a friend did all of that with max. loads.

F. Guffey

do that bump gotta do that bump

 

[fguffey]

When sizing, have the shell holder contact the botton of the die when sizing.

You are repeating something you read on the Internet; if the shooter is going for the .002" clearance and in the perfect world when the die is adjusted to contact the die with the additional 1/4 turn the OP is sizing cases for minimum length. Or as reloaders on reloading forums like to say 'full length size'.

Reloaders are consumed by tolerances, SAAMI this and SAAMI that etc. etc., but they have a problem with the number of times a case is fired. I keep hearing that old story about all you have to do is fire the case 5 times while neck sizing and then start over by full length sizing; and I always ask how is it possible to start over with a case that has been fired 5 times?

I am the fan of measuring before and again after.

F. Guffey

 

[M-61]

Back when I started there was no one telling me 'this is how it is done'.

That I believe.

 

[243winxb]

Most of the brass will chamber but a few will not.

When sizing, the shoulder may not always make contact with the die in the shoulder area. These will chamber.

When the die is back off the shell holder a tiny amount, some brass shoulders may contact the die. But not push the shoulder back enough. These will not chamber.

May happen with 2 or 3 firings if loads are not near maximum.

If using a progressive press, each station may give a different shoulder bump. Seen it with Dillon shell plates.

 

[ireload2]

I believe in Oral Roberts, professional exhibition wrestling and guffey.

 

[fguffey]

When sizing, the shoulder may not always make contact with the die in the shoulder area. These will chamber.

If the case gets sized when the ram is raised the shoulder of the case will contact the shoulder of the die. And then there is that part where you assume, you assume the shoulder moves back and I say it is impossible to move the shoulder back if the die has full body support.

F. Guffey

 

[hammerjack]

It could a donut on the inside at the base of the neck if your bullets are setting deep.

 

[BenPerfected]

If the case gets sized when the ram is raised the shoulder of the case will contact the shoulder of the die. And then there is that part where you assume, you assume the shoulder moves back and I say it is impossible to move the shoulder back if the die has full body support.

F. Guffey

Good evening Guff,
I’m thinking I may be getting what you are saying. How is it possible to use a full length size die and move the shoulder back? For that to happen, the now compressed case walls and shortened “bumped” shoulder would have to move the brass.....where? Maybe another way of explaining this process is that the excess brass from the full length sizing & shortened shoulder moves brass to the inside of the case wall.
Think about it...
Ben

 

[expiper]

seee,,,,guffy was right all along,,,,,its all smoke and mirrors,,,,Roger

 

[hogpatrol]

My vote's for new brass or at least try a couple new ones to see if the problem goes away.