Shoulder bump .30-06

[Odyssey]

My first time sizing a rifle case. I'm using a RCBS Precision Mic I inherited. I am not trying to set the shoulder for a specific rifle at this time. I inherited several fired cases that need resizing. I do not own the rifle they were fired in. My .30-06 is a Remington Gamemaster 760 pump.
I measured a 20 rnd. box of new factory Winchester SuperX 150 grain using the RCBS mic and recorded a range between 0.0 to -3.5. I then measured 7 rnds. from a second box of the same factory new ammo and recorded a range between -0.5 and -6.0. My results indicating factory shoulder bump on this specific factory new ammo of 0 to -6.0 according to the RCBS mic.
Based on the above, where would I set the shoulder bump using the Lee full length sizing die?
The Average of all rnds. measured is -1.7. My thought was set my FL sizing die to measure -2.0 bump.
I want to make sure my thinking is correct to assure a safe reloaded cartridge.
I understand I could fire form a few rounds in my rifle and then set my sizing die for optimization in my rifle. However, I don't like that rifle and plan to replace it. My goal at this time is to load the brass I have to a safe factory spec.

 

[msilbernagel]

Well first, congratulations.. I hope you are reading everything you can get your hands on! This is certainly a pasttime for learners.

Are you using some type of headspace gauge, or only the calipers?

 

[98dynagld]

Take a sized piece of brass and put it in the rifle and close it. If it doesn't close size it a little more.

 

[okie]

GUFFEY!!!

 

[Uncle Ed]

Fire some of your factory loaded ammunition and measure the fired case. Then set the die up for .002 to .004 shoulder bump. Right now you do not know your rifles chambers headspace to the shoulder and you need to fire some factory ammunition and measure them.

With that being said the first rifle I purchased after getting out of the military in 1973 was a Remington Gamemaster pump. I set the RCBS resizing die up per the instructions with the die making hard contact with the shell holder and press cam over. And in over 20 years of reloading for this rifle, I never had a case head separation and the cases died of split necks. I was lucky, chambers and dies vary in size and my RCBS die was a good match for my chamber. Your RCBS Precision Mic will tell you how much to bump the shoulders back if you fire some factory ammunition.

With the cases fired in another chamber, I would recommend pausing at the top of the ram stroke for 4 to 5 seconds. This will reduce the amount of brass spring back after sizing and make the shoulder location more uniform.

NOTE, the 760 Gamemaster pump does not have the primary extraction strength of a bolt action. And your resized case body diameter should be .003 to .005 smaller in diameter than a fired case. This will ensure the case springs back from the chamber walls and extracts reliably.

Trust me before I bought my Rockchucker press I tried resizing the cases with a Lee Target Loader below. The second time I reloaded and fired the cases they would not extract until the cases cooled off.

 

[K22]

Since you're attempting to use cases fired in presumably a different rifle chamber I wouldn't be using shoulder bump at this point to adjust your sizing die. I would wait until the cases are fired formed in your rifle before I focus on shoulder bump. Also you may find that you require more bump than the conventional .001 to .002 because you're sizing for a pump action. But that come later.

Although I stopped the practice of using cases from unknown sources years ago, when I did, the following is the process I used but in bolt action rifles. Your rifle chamber becomes the gauge for adjusting your sizing die until the cases are fired form in your rifle chamber. This becomes a trial and error process until you obtain the proper fit.

Accordingly, I installed the die so the ram securely contacted the shell holder then turned the die down 1/8 turn to produce a slight amount of cam over. Sized, then checked in the rifle chamber - don't force the case to chamber. Keep adjusting until the case chambers with only slight resistance. You don't want to over do the sizing, just enough so the case chambers without much resistance.

A pump action makes this process more difficult but it can be done if you're patient and take your time. Personally I wouldn't try this for a pump action but that's just me. I'd start with new cases.

 

[mmcu]

In addition to what has been stated above, be sure to remove the spent primer before taking any measurements with your RCBS Precision Mic.

 

[Odyssey]

My concern was the 0.0 to -6.0 range I was measuring on factory ammo. This suggests that this range is common for factory ammo or, at least this factory ammo, and that the mfr intentionally targets max bump of 0.0 and is not concerned with as much as -6.0
I want to reload this brass to reliably fire in any .30-06 rifle. With this objective, what should be my target bump? I was thinking -2.0 based on the measurements obtained with my mic and the factory ammo I measured. Should I go further such -3.0?

 

[Ggmac]

Its not bump in new unfired factory ammo its called min or max saami ammunition specs . Just like chamber specs , ammo has min and max ammo specs . Its generally smaller in more places besides just shoulder length . Neck dia , shoulder diam and height and all the way down to the .200 line . Even the solid base varies among manufacturers.

 

[centerlineseal]

Fire some of your factory loaded ammunition and measure the fired case. Then set the die up for .002 to .004 shoulder bump. Right now you do not know your rifles chambers headspace to the shoulder and you need to fire some factory ammunition and measure them.

With that being said the first rifle I purchased after getting out of the military in 1973 was a Remington Gamemaster pump. I set the RCBS resizing die up per the instructions with the die making hard contact with the shell holder and press cam over. And in over 20 years of reloading for this rifle, I never had a case head separation and the cases died of split necks. I was lucky, chambers and dies vary in size and my RCBS die was a good match for my chamber. Your RCBS Precision Mic will tell you how much to bump the shoulders back if you fire some factory ammunition.

With the cases fired in another chamber, I would recommend pausing at the top of the ram stroke for 4 to 5 seconds. This will reduce the amount of brass spring back after sizing and make the shoulder location more uniform.

NOTE, the 760 Gamemaster pump does not have the primary extraction strength of a bolt action. And your resized case body diameter should be .003 to .005 smaller in diameter than a fired case. This will ensure the case springs back from the chamber walls and extracts reliably.

Trust me before I bought my Rockchucker press I tried resizing the cases with a Lee Target Loader below. The second time I reloaded and fired the cases they would not extract until the cases cooled off.

Lee Target handloading set, ... my very first, in 30-06 as well. My Dad bought it for me in 1975. The primer seater is still my go-to tool of choice!

 

[RegionRat]

My first time sizing a rifle case. I'm using a RCBS Precision Mic I inherited. I am not trying to set the shoulder for a specific rifle at this time. I inherited several fired cases that need resizing. I do not own the rifle they were fired in. My .30-06 is a Remington Gamemaster 760 pump.
I measured a 20 rnd. box of new factory Winchester SuperX 150 grain using the RCBS mic and recorded a range between 0.0 to -3.5. I then measured 7 rnds. from a second box of the same factory new ammo and recorded a range between -0.5 and -6.0. My results indicating factory shoulder bump on this specific factory new ammo of 0 to -6.0 according to the RCBS mic.
Based on the above, where would I set the shoulder bump using the Lee full length sizing die?
The Average of all rnds. measured is -1.7. My thought was set my FL sizing die to measure -2.0 bump.
I want to make sure my thinking is correct to assure a safe reloaded cartridge.
I understand I could fire form a few rounds in my rifle and then set my sizing die for optimization in my rifle. However, I don't like that rifle and plan to replace it. My goal at this time is to load the brass I have to a safe factory spec.

Based on the above, where would I set the shoulder bump using the Lee full length sizing die?
Like you have surmised from the advise above, the ideal thing to do is load specifically for your rifle to avoid over working your brass.

In the grand scheme, you can see that the gage is more or less calibrated to the shoulder datum specs. The one thing you can see in advance of a specific rig, is that you can size to a max of zero on that gage and in theory you would be able to close the bolt on a properly built rifle.

The only problem with this loose theory, is that you are starting from used brass with lots of dimensions in addition to the shoulder datum. If for example brass had been fired in automatics or generous chambers, the other dimensions can also cause problems. If you want to make a habit of taking random brass and sizing it for general use, use a small base die and don't exceed zero on the Mic gage.

For the current rifle, take about three pieces and cycle them about three times with neck size only and then carefully watch the shoulder dimension as you use the rifle chamber as a gage. Continue to neck size only while watching that shoulder dimension grow to the point where it gets tight to close. After three or more cycles, that brass will trend toward the actual chamber size. Keep good notes as always.

Another good thing to learn is to gage the diameters that can affect your performance later on too. The diameter above the web and at the shoulder junction are good to measure. Those need to be done with a micrometer rather than a caliper because they are more sensitive than the shoulder dimension.

I want to reload this brass to reliably fire in any .30-06 rifle. With this objective, what should be my target bump? I was thinking -2.0 based on the measurements obtained with my mic and the factory ammo I measured. Should I go further such -3.0?

You can leave yourself a tolerance on that order and you will be okay 99% of the time. Occasionally when you pick up random brass, a shoulder at that size can still leave a diameter that is snug. In many examples a standard die will fix that when dialed down just a little farther. Again, to get a reliable reset on random brass that you want to go into "any gun" you may want to consider a small base die but it isn't a hard requirement.

As a rookie, I would advise you think about waiting to bulk size until after you have the chamber in hand. That way, you adjust till you know you can close the bolt. A Body Die can make it easy to add corrections to body dimensions after you have sized with a regular die. Again, take it slow till you gain experience and find a mentor if you can.

 

[Odyssey]

With the factory ammo ranging in shoulder set back between 0.0 and 3.5 using my mic, I'm confused why I need not exceed zero on the mic.
In any event, I'm a bit frustrated as it seems turning the FL sizing die in further does not move the shoulder back. How can that be? I disassembled and cleaned the die and the mic. Lee directs to contact shell holder, then additional 1/4 - 1/3 turn. I have added as much as an additional 3/4 turn beyond recommendation without measuring a move in the shoulder. My die and setup is generating -1.0 to +3.0. I plan to talk to Lee tomorrow. I recently sent the die in for refurbish. Maybe there is a piece missing that creates the shoulder position.

 

[RegionRat]

With the factory ammo ranging in shoulder set back between 0.0 and 3.5 using my mic, I'm confused why I need not exceed zero on the mic.
In any event, I'm a bit frustrated as it seems turning the FL sizing die in further does not move the shoulder back. How can that be? I disassembled and cleaned the die and the mic. Lee directs to contact shell holder, then additional 1/4 - 1/3 turn. I have added as much as an additional 3/4 turn beyond recommendation without measuring a move in the shoulder. My die and setup is generating -1.0 to +3.0. I plan to talk to Lee tomorrow. I recently sent the die in for refurbish. Maybe there is a piece missing that creates the shoulder position.

Lets break this down a little slower.

Why not exceed zero? This is to avoid the question about putting random brass in random chambers, not true when you are custom loading for a specific chamber where you can just bump down about one or two mils for a bolt gun and about two to four for an auto. So keep the two topics separated. The "don't go over zero" is for when you don't know the actuals ahead of time. It is okay to go to values above zero when you know the chamber dimensions.

In any event, I'm a bit frustrated as it seems turning the FL sizing die in further does not move the shoulder back. How can that be? This is because we don't get to control diameters separately from shoulder lengths. Imagine a chamber that has a generous cut in both shoulder length and diameter. When you consider the taper of the die versus the chamber size, the diameters being pushed in force the material to go forward, at least until the die shoulder actually comes within the spec length to the shell holder.

Things with the die seem to happen all at once to beginners. As they keep turning the die down, if they only watch the shoulder length, they get surprised when all of a sudden the shoulder seems longer, but then suddenly it is being pushed down.

Take this process slow at first, and use Imperial lube on the die to avoid getting stuck. You will eventually see that a standard FL die on a standard shell holder, should bring the shoulder to just zero or about -2 if they had their act together when they made the die, for when the die touches the shell holder.

Later on, to avoid over working the brass, you may either use an incremental shell holder set, or back the die off in small increments. I'll drop a link to the incremental shell holders.

BTW, as you accumulate shell holders, keep track of which ones you have inspected cause some of them are not cut to spec and mix matching them without keeping track under those circumstances can lead to confusion.

Incremental Shell Holders

 

[SSL]

I don't know if this is a common issue, but the only 760 I ever worked with belonged to one of my friends. He had issues ejecting fired cartridges from his reloads. We finally traced it to needing a 'small base' sizing die. Problem solved. As I said, don't know if this is common, but good to keep in mind.

 

[Old Navy]

Fire some of your factory loaded ammunition and measure the fired case. Then set the die up for .002 to .004 shoulder bump. Right now you do not know your rifles chambers headspace to the shoulder and you need to fire some factory ammunition and measure them.

With that being said the first rifle I purchased after getting out of the military in 1973 was a Remington Gamemaster pump. I set the RCBS resizing die up per the instructions with the die making hard contact with the shell holder and press cam over. And in over 20 years of reloading for this rifle, I never had a case head separation and the cases died of split necks. I was lucky, chambers and dies vary in size and my RCBS die was a good match for my chamber. Your RCBS Precision Mic will tell you how much to bump the shoulders back if you fire some factory ammunition.

With the cases fired in another chamber, I would recommend pausing at the top of the ram stroke for 4 to 5 seconds. This will reduce the amount of brass spring back after sizing and make the shoulder location more uniform.

NOTE, the 760 Gamemaster pump does not have the primary extraction strength of a bolt action. And your resized case body diameter should be .003 to .005 smaller in diameter than a fired case. This will ensure the case springs back from the chamber walls and extracts reliably.

Trust me before I bought my Rockchucker press I tried resizing the cases with a Lee Target Loader below. The second time I reloaded and fired the cases they would not extract until the cases cooled off.

We have to be near the same age. I bought my first 760 just before getting out of the Navy in 67. Started with a Lee hand loader. As I remember it was a neck sizer die. If I didn't fire them in my gun they wouldn't even chamber a lot of the time. Didn't take me long to upgrade to RCBS also. You post is good advice for the OP.

 

[Uncle Ed]

Odyssey

First off the RCBS Precision Mic is not calibrated to a GO gauge, My Precision Mic reads plus .0025 with a GO gauge in it. Meaning the readings you are getting with factory ammo means nothing.

You need to fire some factory ammo then measure the cases for a baseline measurement and call this zero..

Below is my .308 RCBS Precision Mic, and it is a comparator gauge and not calibrated. You measure a fired case and then set the die up for the amount of shoulder bump you want.

Below is an image of what happens when full length resizing and the shoulder location. You are over thinking this, follow the dies directions for setup with press cam over.

Below these .308 cases were fired in a brand new Savage rifle with the die setup per the instructions. Meaning the maximum amount of shoulder bump with the die making hard contact with the shell holder and press cam over. The reloading manuals and the dies instructions tell you the casrtridge should then chamber in any rifle.

Bottom line, you do not have a bench rest rifle, you have a pump action Remington 760 Gamemaster. Here in Central Pa. they are known as an Amish machine gun, and made for fast action shooting. And if the ammo doesn't chamber or eject you may as well just throw rocks.

 

[K22]

Some food for thought:

Unless I'm missing something, a 30 06 Rem 760 in pump action is a big game hunting rifle; pure and simple, right?

How many rounds do you expect to expend? In other words, is it worth the frustration, potential problems, etc. to try and use cases fired in different rifles of unknown origin for the number of rounds typically consumed in this type of rifle for that type of purpose?

Also, these rifle are not known for their accuracy - they are designed for hunting big game animals with a relatively large vital area and fast follow up shots.

Most of the guys I know that have 760's shoot 3 - 5 rounds sight in checks before deer / bear season, then rarely shoot more than 1 to 3 rounds after that in season if they're lucky.

By starting with new cases, properly sizing from a measured baseline of a fired case from your rifle and dedicating a group of cases to that rifle you should be able to get many hunting seasons with a group of cases that function flawlessly which is critical in a hunting situations.

It can be tricky sizing cases for a pump action because they tend to expand more than a bolt. If you start with new cases, you can minimize potential problems. Trying to use a set of cases for any rifle can be done but often leads to oversizing and the risk of head separations as shown in Uncle Ed's post.

 

[Mikey_P]

...you have a pump action Remington 760 Gamemaster. Here in Central Pa. they are known as an Amish machine gun,

Say now Uncle Ed - you just put a smile on this eastern PA boy's face

Mike

 

[Uncle Ed]

Say now Uncle Ed - you just put a smile on this eastern PA boy's face

Mike

Nothing better than a 760 Gamemaster and hunting on the Tuscarora mountain in "Pennsyltucky".

Then after the hunt, drinking a few Yuengling beers by the wood burning stove.

 

[Odyssey]

Much appreciated. I am clear that the RCBS mic is a comparator and not a go gauge. I compared 25 rnds of factory ammunition to each other and measured a range between them of -0.5 and -6.0. This factory ammunition cycled just fine in the PumpMaster. I'm now comparing fired brass, sized through my FL die, to the factory un-fired rnds. All using the same mic so, whatever this mic measures as zero is only a reference.
I acknowledge that sizing brass for a specific rifle chamber is the desired approach when seeking accuracy. I inherited this GameMaster and did not enjoy shooting it. I plan to trade or sell for a modern bolt action. Certainly I could wait, size and reload the brass I have after I own a gun I desire to match it to. Doesn't matter if I am generically sizing or, sizing to a specific chamber, I still need to understand and learn why factory ammo has as much as -6.0 set back on my mic and I'm getting +2 to -2 through my die. If I can't control the process to achieve desired set back, it doesn't matter what the target is I'm working toward.
I think I'll go back to .38spl and .45 Colt and occupy my time that way