Bumping sholders

[B23]

To just pick an amount to bump the shoulder back before the case has fully formed to the chamber and reached zero head space IMO isn't the best way to go about sizing cases.

 

[Bill Norris]

To just pick an amount to bump the shoulder back before the case has fully formed to the chamber and reached zero head space IMO isn't the best way to go about sizing cases.

Fully formed brass will always give better results.

 

[TIMO]

The correct amount of shoulder bump for a given rifle is important no doubt due to not over-sizing the brass. BUT, if the shoulders are not bumped enough in some cases the hard bolt close will produce vertical in groups. I've seen this more than once. I don't think we should get wrapped around the axle of the .002 bump being standard. I am not claiming it will take more than .002 in every rifle. That's why it is critical to measure and test if needed.

Like Bill said, every chamber/rifle is different, .002 is just a number, not set in stone. The ideal setup would be to have a sizing die for each chamber/rifle. Not always possible but could be somewhat accomplished with specific shims and notes for each. I have two different 30BR rifles cut with different chambers, I have found a happy medium when sizing brass for either one without adjusting the sizing die. Maybe I am just lucky but, .001 to .0015" is not going to break the bank either way between these two rifles. My targets shows no difference. I do keep the brass separated by rifle.

Just my .02, not thousandths.
Tim

 

[L.Sherm]

If you watch a video of Eric demo showing bump using the " Wheeler" method you will see he has to bump .004 to get no resistance. Its exactly what he's demo is why I try to do the Wheeler method for bump and touch point.

 

[Bill Norris]

If you watch a video of Eric demo showing bump using the " Wheeler" method you will see he has to bump .004 to get no resistance. Its exactly what he's demo is why I try to do the Wheeler method for bump and touch point.

Exactly, and there are plenty of rifles out there that shoot better without having the hard bolt close. Granted annealing the brass, brass condition and sizing die set-up contribute to these factors.

 

[CaptainMal]

Got me laughing. With shell holders of different sizes, dies different and chambers different, your procedure is a joke.

You need to measure shoulder dimensions from fired brass, then test to be sure you are chambering properly. Others have aptly explained both methods.

 

[Webster]

I have been reloading for 50 years and always set my resizing die to just touch the shell holder with the slightest bit of camover. Is that giving me the proper amount of shoulder dimension or too much bump ?

That die setting method makes a lot of assumptions. Chambers are not all alike and dies vary by manufacturer. Like others said if your happy with your results keep doing it. When I bought a Whidden 6BR die I got a free Bump gauge. Just attach it to a cheap Harbor Freight digital caliper. It's good enough for most of us. I probably reloaded for 40 years before I got the bump tool.

The case head to the center of the shoulder on a SAAMi blue print is probably +/- 0.002" and the die +/- 0.002" and +/- 0.002" on the reamer.

Added later:
The gunsmith can run the reamer in a few thou short or long and still pass a go/no go gauge. The dimensions of the bolt lugs and receiver contact also affect chamber length. Where the bolt face sits is in affect part of the chamber. The back .200" of the case head is outside of the actual barrel chamber and sitting against the bolt face.

 

[Webster]

No matter the maker or brand of dies used, that a person buys for reloading. I often wonder, with so many questions asked about how to use/adjust them, show up on the various sites, does anyone read the instructions that come with the dies and what the maker advises on how to set up and adjust the dies for proper use and results ?

The instructions are for beginners that don't have tools to measure things. Their instructions should work but you may get longer case life and if your lucky better accuracy if you bump the shoulders 0.002". Imagine how sloopy a factory case is in the chamber.

 

[Coyotefurharvester]

He might be running a gas gun. Has not given any details. I've loaded for several factory rifles(standard rcbs dies) where die touching the shell holder to slightly down(16th to an 8th no case in the holder) works just fine. Probably not pushing back shoulders back to factory unfired, that would be hard on brass life.

 

[Oldboy55]

OB55 are you reloading for hunting, informal targets, plinking? Bolt gun, gas gun, break action? Cartridge?

Loading for my M1A

 

[Oldboy55]

He might be running a gas gun. Has not given any details. I've loaded for several factory rifles(standard rcbs dies) where die touching the shell holder to slightly down(16th to an 8th no case in the holder) works just fine. Probably not pushing back shoulders back to factory unfired, that would be hard on brass life.

 

[Oldboy55]

Loading for a newly acquired M1A

 

[Oldboy55]

Ok so I recently also acquired a Remington 40X in .222 Remington. It has a Hart target barrel and when chambering a round it is a slightly difficult to close the bolt. Ive heard that these custom barrels have their own specs. Perhaps I need to bump back the shoulders a bit on that rifle. Even factory ammo is a bit snug. Rifle shoots in one hole at 100 yards but still may not be quite right. Think I need to acquire some additional equipment to check this out. Thank you all fir your assistance.

 

[Bill Norris]

Ok so I recently also acquired a Remington 40X in .222 Remington. It has a Hart target barrel and when chambering a round it is a slightly difficult to close the bolt. Ive heard that these custom barrels have their own specs. Perhaps I need to bump back the shoulders a bit on that rifle. Even factory ammo is a bit snug. Rifle shoots in one hole at 100 yards but still may not be quite right. Think I need to acquire some additional equipment to check this out. Thank you all fir your assistance.

Absolutely, I would check the bump on it. As I mentioned above I have seen the tight-hard bolt close cause vertical in the groups.

 

[K22]

The correct amount of shoulder bump for a given rifle is important no doubt due to not over-sizing the brass. BUT, if the shoulders are not bumped enough in some cases the hard bolt close will produce vertical in groups. I've seen this more than once. I don't think we should get wrapped around the axle of the .002 bump being standard. I am not claiming it will take more than .002 in every rifle. That's why it is critical to measure and test if needed.

^^^^^ This

 

[Coyotefurharvester]

You need to strip the bolt on the 40x to use bolt feel to setup sizing die. Or use the spent primer method, you will need a few fired cases (and a caliper) with just the spent primer removed. The M1A needs a bit more bolt head clearance (HS) than a typical bolt gun.

 

[K22]

I won't repeat the solid advice already posted. However, I would like to add that this is one of the most important steps in reloading bottle neck rifle cartridges and one of the most misunderstood in my opinion.

I consider a bump gauge and caliper essential reloading equipment for bottle neck rifle cartridges, even hunting loads.

Every reloader would do well to learn the basic principles involved and how to set their F/L to produce optimum sizing.

 

[6MMsteve]

Where is Guffer at I remember the first time I got on this site He got me so confused...I misssss ol Guffey

 

[swd]

There are so many variables here! Dies are far less precision than they would like you to think. I have rarely seen one that over sized the headspace dimension, but it does happen. But I have seen more than a few that either wouldn’t bump the shoulder back enough or at all. I had a 7WSM die a client brought in that I ended up taking .027” off the bottom. Also if even dies are “perfect” and your looking for .002” shoulder bump, headspace tolerance between go and no go can be .003”-.004” and even more on some cartridges and still have a chamber in correct headspace. Also if you anneal shoulders set back more and do so more consistently. So point being the only real way to set up your dies is to measure shoulder bump either with a chamber gage, preferably made with the same reamer the gun was chambered with, or take the firing pin assembly out of the bolt, clean all the grease out of the lug recess and set up a dial indicator at the back of the bolt and check your sized case while you adjust the die.