Shoulder bump?

[Garbageman]

Trying to refine my loads for my RPR in 6.5C. Was using hornady brass/bullets, now I'm experimenting w/ alpha brass and berger 140's. I'm using a redding FL 9X die

The hornady brass after firing measures 1.5295 to the shoulder using a whidden shoulder bump gauge. The alpha brass measures 1.5268. I measured five cases and averaged.

Both have been fired twice. Why is the hornady longer? Brand new alpha brass measures 1.5250.

So, do I set my die to push the shoulder back to 1.5248 (1.5268-.002) on the alpha brass or will the alpha brass grow to the same measurement as the hornady and I should set my die to push the shoulder back to 1.5275 once the alpha brass is long enough to do so ?

 

[Bill Norris]

From my limited experience the Alpha seemingly takes longer to fire form than other brass so you may need to make some adjustments.

 

[Straightshooter1]

Trying to refine my loads for my RPR in 6.5C. Was using hornady brass/bullets, now I'm experimenting w/ alpha brass and berger 140's. I'm using a redding FL 9X die

The hornady brass after firing measures 1.5295 to the shoulder using a whidden shoulder bump gauge. The alpha brass measures 1.5268. I measured five cases and averaged.

Both have been fired twice. Why is the hornady longer? Brand new alpha brass measures 1.5250.

So, do I set my die to push the shoulder back to 1.5248 (1.5268-.002) on the alpha brass or will the alpha brass grow to the same measurement as the hornady and I should set my die to push the shoulder back to 1.5275 once the alpha brass is long enough to do so ?

Because different brass can have different thicknesses AND different a difference in hardness, there's going to be a difference in spring back. If you anneal the cases after every firing, you should have much less difference in spring back than .003.

If you're going to use the same die to size both cases and not anneal, yes . . . you'll have to make a die adjustments to get the same bump measurement for the two brands of brass.

 

[Coyotefurharvester]

What problems are you having chambering fired unsized brass?

 

[6Creed73]

As @Straightshooter1 said, brass thickness difference as well as the makeup of the brass itself is why. Separate your brass, at the very least, by manufacturer. Then set you die up and size all the Hornady. Repeat for the Alpha. This is what I do as most of my brass is also Hornady and Alpha.

 

[Garbageman]

What problems are you having chambering fired unsized brass?

I just tried several of the fired cases and they chambered easily. Just leave them alone until they grow to the point that I cannot chamber easily?

 

[Garbageman]

I should have explained better. I will not be mixing the brass, only plan on shooting the alpha. It was curiosity that caused me to measure the hornady

 

[6Creed73]

I should have explained better. I will not be mixing the brass, only plan on shooting the alpha. It was curiosity that caused me to measure the hornady

Yeah, it won't form exactly the same. At least not on one firing, maybe not even two. Even then, brass thickness differences can make your measurements slightly off.

 

[6Creed73]

I just tried several of the fired cases and they chambered easily. Just leave them alone until they grow to the point that I cannot chamber easily?

That's up to you. Some like to FL size after every firing, some like to neck size only for 2 or 3 firings then FL size. I will usually neck size only for two firings, then I either FL size or neck size again but with a shoulder bump. I just try to move the brass as little as possible.

 

[Lone Hunter]

Trying to refine my loads for my RPR in 6.5C. Was using hornady brass/bullets, now I'm experimenting w/ alpha brass and berger 140's. I'm using a redding FL 9X die

The hornady brass after firing measures 1.5295 to the shoulder using a whidden shoulder bump gauge. The alpha brass measures 1.5268. I measured five cases and averaged.

Both have been fired twice. Why is the hornady longer? Brand new alpha brass measures 1.5250.

So, do I set my die to push the shoulder back to 1.5248 (1.5268-.002) on the alpha brass or will the alpha brass grow to the same measurement as the hornady and I should set my die to push the shoulder back to 1.5275 once the alpha brass is long enough to do so ?

Forgive my ignorance but what is a Redding FL 9X die? I know what FL is but where does the 9X come into play? I googled it and didn’t find anything. Thanks

 

[Garbageman]

Forgive my ignorance but what is a Redding FL 9X die? I know what FL is but where does the 9X come into play? I googled it and didn’t find anything. Thanks

No idea. That's just printed on the die

 

[BoydAllen]

One brand is harder and springier than the other. This also comes into play when setting a die for shoulder bump, because a springier case will require a slightly different setting to produce the same result. I run into this with work hardening from multiple fire/size cycles. For my 6PPC a die adjustment that produced a thousandth bump on much used brass gave three and a half thousandths on formed and twice fired.

 

[JFrank]

I just tried several of the fired cases and they chambered easily. Just leave them alone until they grow to the point that I cannot chamber easily?

Correct.

 

[Eagle Six]

There may be a five digit numeric number on the label of your die which may be more descriptive than the 9X.

 

[M-61]

I just tried several of the fired cases and they chambered easily. Just leave them alone until they grow to the point that I cannot chamber easily?

That’s correct

 

[BoydAllen]

Correct.

I would set the FL die to just produce the longest as fired dimension to size them for their next firing, and then adjust for the next time around, depending on the same procedure produces cases that are tight after sizing. There can be disadvantages to letting cases get tight at the back. They can take a set that results in less sizing from a given die. For a Die that does a lot of sizing at the back this probably would not be an issue, but for a custom die that does only a little it could.

If you take the cases that you have, and for each brand, after depriming, put a washer of Scotch tape on the head, that will give you cases that are too tight to size back from, adjusting a little at a time, when you get to the point where you only have the slightest feel of the case when you chamber it, set the die for two thousandths more bump and you should be GTG for several more firings, until the brass work hardens to the point where that setting does not give you the bump that you want.

 

[Coyotefurharvester]

I would set the FL die to just produce the longest as fired dimension to size them for their next firing, and then adjust for the next time around, depending on the same procedure produces cases that are tight after sizing. There can be disadvantages to letting cases get tight at the back. They can take a set that results in less sizing from a given die. For a Die that does a lot of sizing at the back this probably would not be an issue, but for a custom die that does only a little it could.

If you take the cases that you have, and for each brand, after depriming, put a washer of Scotch tape on the head, that will give you cases that are too tight to size back from, adjusting a little at a time, when you get to the point where you only have the slightest feel of the case when you chamber it, set the die for two thousandths more bump and you should be GTG for several more firings, until the brass work hardens to the point where that setting does not give you the bump that you want.

I agree, a fl sizing die can be set to produce neutral (no change) to datum length. This may require several cases as repeatedly adjusting the die and sizing the same piece of brass is problematic.

 

[JFrank]

I would set the FL die to just produce the longest as fired dimension to size them for their next firing, and then adjust for the next time around, depending on the same procedure produces cases that are tight after sizing. There can be disadvantages to letting cases get tight at the back. They can take a set that results in less sizing from a given die. For a Die that does a lot of sizing at the back this probably would not be an issue, but for a custom die that does only a little it could.

If you take the cases that you have, and for each brand, after depriming, put a washer of Scotch tape on the head, that will give you cases that are too tight to size back from, adjusting a little at a time, when you get to the point where you only have the slightest feel of the case when you chamber it, set the die for two thousandths more bump and you should be GTG for several more firings, until the brass work hardens to the point where that setting does not give you the bump that you want.

Cool idea’ perhaps a few extra steps around the barn for a possibility a case might take a set that I couldn’t size out with a pull of a handle, for me the first indication i’m reaching a fully formed case is slight resistance chambering a spent round, I want to record that chamber data, so for myself I’d feel I would be over complicating matters with scotch tape and recording data from seperate batches of brass and up tape layers etc. whereas I could just measure the FF brass and be done

 

[Coyotefurharvester]

I will just continue to use a spent primer method to measure actual bolt to cartridge head clearance. And an ammo checker for my hunting/AR ammo. Either makes setting up a sizing die very easy.

 

[Shooter13]

No idea. That's just printed on the die

I have RCBS dies that one says 4X and one says 5X, just saw that and wondering it it means anything (like Harrells dies?).