Shoulder bumping ques.

[ilmonster]

I thought I would tap into the brain trust here to enlighten myself a bit. I currently reload .223 for my Remington 700 SPS Tac (in a Bravo stock, Timney 510, etc.). I did OCW testing and came up with 23.0 gr. of TAC under a Hornady 75 gr. BTHP. Can consistently get 0.5 MOA groups. So the gun and load shoot well.

My question regards bumping the case shoulder back. The rounds I shoot come from and only get reloaded for the one rifle. Trying out some 3 times fired cases, I can chamber the empty fired case just fine back in the rifle. If that’s the case, do I necessarily need to bump the shoulders back 1 to 2 thou? I full length resize them in a Forster FL sizing die. Will they eventually grow from firings where I wouldn’t be able to chamber the empty case, and hence would need to bump the shoulders back .002”?

Conversely, I have some .223 ammo I shot through my BCM AR (.223 rounds in a 5.56 chamber), and when I try and chamber those in the Rem 700, the bolt will not close. That makes sense, having first been fired in a 5.56 chamber. I’m guessing those would need to have the shoulders bumped back until the case barely chambers, and then bump it back another .002”, correct? I would buy and use the Redding Competition Shellholder set to bump these back (haven’t tried that yet).

So the two questions are, 1) do I necessarily need to bump the Rem700 fired cased back .002 if they chamber fine? 2) would I need to bump the AR fired .223 cases back at least .002” to get them to be usable in the Rem 700,? Thanks!

 

[spife7980]

If they chamber fine then no need to further size. Find the point where they will no longer easily size and then take .002 from that as the ideal location for the shoulders.

You would likely need to size the AR brass smaller to fit into the bolt chamber, how much is necessary will have to be measured and tested. The issue with this though is that you need to measure more than just the shoulder location. It could also be the base diameters thats causing chambering issues and that would be remedied with a small base die which is a thousandth or two smaller at the bottom of the case.

 

[EchoDeltaSierra]

If it were me...

Weight sort out 50, 100, 200 (or whatever) pieces and make that a dedicated lot for the R700. Fire those in the bolt gun then bump those shoulders .001” - .002”. Load those for precision from that rifle.

Take the rest of the brass and SAMMI size it to run in the gas gun.

Don’t mix gas gun and bolt gun ammo.

Just an opinion.

 

[_Raining]

I full length resize them in a Forster FL sizing die

What does this mean?

 

[ilmonster]

Sounds good regarding the gas gun spent cases. I'll toss those, and use only the cases that were originally fired in the 700 (which is what I'm doing now). Sounds like unless or until the Rem 700 fired cases don't chamber, I can resize without bumping the shoulders back and be on my way.

Raining, not exactly sure what you're asking, but when I begin to reload the fired cases, I run them through my Forster brand sizing die to get them back to dimensional spec. It is a full length sizing die that sizes almost the entire length of the case vs. just neck sizing the case with a neck sizing die.

 

[spife7980]

Sounds good regarding the gas gun spent cases. I'll toss those, and use only the cases that were originally fired in the 700 (which is what I'm doing now). Sounds like unless or until the Rem 700 fired cases don't chamber, I can resize without bumping the shoulders back and be on my way.

Raining, not exactly sure what you're asking, but when I begin to reload the fired cases, I run them through my Forster brand sizing die to get them back to dimensional spec. It is a full length sizing die that sizes almost the entire length of the case vs. just neck sizing the case with a neck sizing die.

That didnt really answer his question.
Hes asking "how" are you full length sizing, youre just telling him that you are, not "how".

I assume that you are running them up into the full length die but only just enough to size the neck and maybe a bit of the base and situated in a location where it touches the shoulders but doesnt move them back any?

There is a spec of around .007" of play in the cartridge shoulder spec where something can still be "in spec", thats huge for us reloaders who try to limit over working of the brass. (Dont worry about the actual numbers matching this print, your comparators actual measurement number on the calipers will differ, its just the difference in the fired vs sized that we care about.

The issue is that with a full length die and a fired case thats not quite full chamber size you have a bit of play/empty space in there. If you were to squeeze the base smaller but with the die is situated high enough up in the press so that shoulders are still unsupported inside of the die then those shoulders can move forward on you so that even though it was "sized" the shoulder location has frown and is now too long for the chamber. Think of it as a playdough snake, you roll it around in your hands and it gets longer.

You could also be sizing it waaaay too small also. We choose .002 as it is enough to get clearance without provided more than needed and shortening brass life.

So I guess a more specific question is: What is the actual length of the shoulders to the case face on a piece of brass fired from your 700 and what is the length on the sized cases?



Some good informative videos

 

[ilmonster]

I don't remember what the base to shoulder length was last time I resized some of the brass. I'll do that this weekend and report back.. Last I remember, I was taking whatever the fired cartridge base to shoulder measurement was and bumping it back .002" not taking into account whether it chambered or not. That was the genesis of my original question - do I need to bump if the fired, but not sized case still chambers fine?

 

[spife7980]

If it fits then no. The brass has not fully expanded to chamber size at that point.

 

[Steel head]

I don't remember what the base to shoulder length was last time I resized some of the brass. I'll do that this weekend and report back.. Last I remember, I was taking whatever the fired cartridge base to shoulder measurement was and bumping it back .002" not taking into account whether it chambered or not. That was the genesis of my original question - do I need to bump if the fired, but not sized case still chambers fine?

When I’m lazy I just neck size.
I can usually neck size 4 times before the cases get tight.
Then I anneal and bump the shoulder back then neck size again.

When I do bump the shoulder back I bump it .002 from longest measurement on cases.
It’s always about 1.633 for the longest case for my last two barrels so I bump to 1.631.

 

[ilmonster]

Thanks for all the feedback gents!