Shoulder Bump

[Mark37082]

Just put my first firing on ADG 7RM brass. I loaded with 5 different bullets and minimum to moderate powder loads for the first firing as I was not sure where pressure issues may start on this new brass. Never reached any obvious pressure issues (no heavy bolt lift or primer issues). Measuring the shoulder indicates anywhere between 2.1195 and 2.1230 after this first firing. All of the unloaded rounds seem to chamber fine in the rifle. Preparing to load for 2nd firing and thought I would ask the experts for your suggestions on where to set my bump. I would think consistency would be wise, but given the variance I am not so sure. New factory ammo measures 2.1090. Thoughts /suggestions?

 

[jraulsten]

I wouldn't bump it at all if they chamber. New, good brass shot with light to moderate loads will (or should) take more than one firing to fully form to your chamber.

 

[jimbires]

neck size only until it starts to get tight to chamber , then you can set up your dies to bump the shoulder . if you have the dies set for the shoulder bump , from loading the old batch of brass , just use the dies as set . since the chamber hasn't changed , the brass will use the same setting .

 

[mudflap621]

I wouldn't bump it at all if they chamber. New, good brass shot with light to moderate loads will (or should) take more than one firing to fully form to your chamber.

This! I'll also add its best to pull your ejector and Firing pin. If your bolt falls closed on a fired case your not ready to bump shoulder. Once you get slight resistance on disassembled bolt you will want to slowly start sizing down until it drops free and add another .001"-.0015". If u use one peice of brass sized down multiple times to get this measurement it's good to test on a once sized peice as it might be a little different.

 

[mudflap621]

neck size only until it starts to get tight to chamber , then you can set up your dies to bump the shoulder . if you have the dies set for the shoulder bump , from loading the old batch of brass , just use the dies as set . since the chamber hasn't changed , the brass will use the same setting .

If you are using a full length die you don't need to run and buy a neck die just slowly work down until you size 95% of neck just making sure not to bump shoulder until fully formed to your chamber.

 

[Mark37082]

Thanks. It is a new rifle as well. I don't have any fully fire formed brass yet. New Forester dies so I'm kind of starting from scratch. I guess I will just load up some of my cheaper bullets after neck sizing and see if I can get more shoulder consistency after firing. I do have an old Lee collet neck sizing die that I used on the new brass. I'll run IMR4831 in a moderate load as I have an ample supply.

 

[jimbires]

Thanks. It is a new rifle as well. I don't have any fully fire formed brass yet. New Forester dies so I'm kind of starting from scratch. I guess I will just load up some of my cheaper bullets after neck sizing and see if I can get more shoulder consistency after firing. I do have an old Lee collet neck sizing die that I used on the new brass. I'll run IMR4831 in a moderate load as I have an ample supply.

sounds like you have what you need . I'll work with 4 or 5 pieces of brass until they get tight to chamber . then I get my die set to bump the shoulder . once the full length die is set you can size the brass without the neck sizing only step . I'm not sure how you set your die for the shoulder bump . I really like the redding competition shellholder sets . these are easy to use and repeatable . if you're not familiar with them ,there is probably a few you tube videos on how to use them .

Competition Shellholder Sets - Redding Reloading Equipment: reloading equipment for rifles, handguns, pistols, revolvers and SAECO bullet casting equipment

Reloading equipment for rifles, handguns, pistols, revolvers, custom dies, bullet casting equipment, powder measuring and weighing equipment, bullet seating dies

www.redding-reloading.com

 

[Texis]

Bumping over works the shoulder. FL size case, mandrel the neck ID and let the chamber form your brass' shoulder. Keep "your" brass separated form OP brass.

 

[Mark37082]

Bumping over works the shoulder. FL size case, mandrel the neck ID and let the chamber form your brass' shoulder. Keep "your" brass separated form OP brass.

I believe you are saying the same thing as the other responders. I am going to go another firing after neck sizing. Hopefully this will complete the fire forming to my chamber.

Jim - don't have a set of the Redding shell holders. I have looked at them but haven't pulled the trigger yet. It sounds like a good process after chamber forming the brass. Otherwise it will be slow process of getting the die set perfectly for 20 thousands bump.

Great advice from everyone. I really appreciate it.

 

[mudflap621]

2 thousandths bump! .002 it will go quicker than you think it's not much.

 

[Mark37082]

Typo. But thanks for following through on this.

 

[mudflap621]

Just wanted to make sure! It will be quick and painless. If your only loading with that die for one chamber once it's set your golden.

I'm slowly acquiring sizing dies to have one for each specific rifle it makes life so much simpler IMO.

 

[Mark37082]

I usually do the same with sizing dies. I try to buy a new set of dies when I buy a new rifle. The only problem is I keep buying new rifles. Looking at a new 280ai or STW, but hopefully I can come to senses. This getting to be expensive, but fun. I'm also starting to upgrade dies I already have. Should have thought about "buy once and cry once" when I started this hobby.

 

[jimbires]

I have a few sets of the comp shellholders . I get very consistent shoulder measurements . I have 3 different 7mm-08's , and one set of dies . I just use the correct shellholder , and make sure the die is making firm contact with the shellholder . it's that easy . a lot cheaper than a new die for each rifle .