Shoulder Bump

[JustMe2]

Agree with rsbhunter's explanation and others that said you DO NOT NEED new equipment to bump shoulders back. Your full length die already does that. Just adjust it correctly. You are reading too much garbage and obviously confusing yourself. It doesn't sound like you are a competitive shooter so you don't need all the super expensive equipment these forums keep pushing. If it fits in your rifle easily, that's all you need and your rifle will still shoot accurately enough for inside 500 yards. If you want to spend lots of money chasing small groups and shooting 1000+ yards (which is what this forum is about), then you can worry about how much you're bumping, what's your tall target doing, etc, etc, etc. Don't over think this stuff.

 

[grry10]

You can just FL size and we did it for years. I now use the .002 shoulder bump method to keep my brass feeding properly while staying close to fireformed to the chamber and to keep from overworking my brass. It is a personal choice. I found that if I neck sized only occasionally I had a stiff bolt when feeding after a number of firings or if I let the brass get too dirty.

 

[rsbhunter]

I agree with both the above responses....shoulder bump insures the reliability of ammo to function as far as fit...along with trimming, etc. I know I almost panic when I'm in a match and I go to close the bolt and get a slight resistance on bolt close....I check all my cases for bump when resizing, but I bump so little that if I get even a little more "springback" than normal, I get a stiff bolt. For hunting, I almost double the shoulder bump.....if I miss A target , that's one point, if I miss A mulie or elk that I've hunted for, for 3 days, because my bolt won't close on a round, that's tears!!!!!! rsbhunter

 

[milboltnut]

check out this crazy crap...from a guy from another forum.

There is the chamber shoulder and there is the case shoulder. And I have found it impossible to move a shoulder back, I cannot move the shoulder of a case back and I cannot bump it back.

For years reloaders have talked about the dreaded donut and then they claim they "move the shoulder back", if they could move the shoulder back, they could eliminate the dreaded donut.

Reloaders assume they are moving the shoulder back when they are sizing a case and then someone that has never put any thought into what was happing to the case when sizing told them they were moving the shoulder back.

Gee where did he get this from...

I make gages, when measuring the length of a case from the datum to the case head I use a datum of .375" with a length/height gage. I have Wilson case gages with a straight edge and a feeler gage.

SO what does this case on the right need ?

 

[grry10]

It appears to me that the case on the right hasn't been sized. I disagree with your statement that you can't bump a shoulder. If you've ever formed brass you know that you can move a shoulder, it is done all the time. A .002" shoulder bump is less than half the thickness of a dollar bill.

 

[spladi]

I have been reading a lot about bumping the shoulder back when fl sizing. My question is why do I need to purchase more reloading equipment when I have been sizing my brass to fit my case length case gauge an having no problems. Just asking what am I missing.

You can go a long way with case prep, bullet seating etc. etc. but it depends on your intentions, match use or just general respectable accuracy. You sound like acceptable accuracy is where you are at and that's fine. Generally, about .003" or less bump, when needed is enough, you will need some tools to check this. Calipers and headspace checker by Hornady. To much bump can cause ignition problems and short case life.

 

[WildRose]

I use these. Each shell holder varies by .002. Put my gun on the bench and start with least amount of shoulder bump, resize 5 pieces, if the fit is to tight in my rifle chamber I move to the next shell holder bumping it additional .002. Once I have good cycling and chamber fit I stop and then size all my brass. I then know I've bumped my shoulder back just enough to fit my rifles chamber and not a gauge. I then check OAL of the brass and trim as needed. Just my process but it's simple and produces excellent results for me.

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Same here, they are a big help especially with big cases.

 

[WEATHERBY460]

Is it better to compare to the chamber, or compare to a once fired case to find the .002" of bump?

 

[birddog 68]

I am curious about this also. I have been waiting until the bolt closes with some resistance (usually after 3rd firing) and then try to bump it back .003 from there. So I measure the case and don't worry about the chamber and have had no problems.
That's how I do it and has worked well but I'm just a hunter out to 500 yards and others have way more experience than I.

 

[JAYgs8163]

Is it better to compare to the chamber, or compare to a once fired case to find the .002" of bump?

I use my chamber and the Redding competition shell holders to do it. Has served me well.

 

[JakeC]

Is it better to compare to the chamber, or compare to a once fired case to find the .002" of bump?

I don't think it matter which you pick, it's the act of picking one that's repeatable, which is probably going to be the once fired since you can mark one and keep it forever. It's going to be super close to the chamber anyway in length.


to the OP, here's my take so far: I actually got all my brass once fired before I headspaced my prefit. Then I used my go gauge and the once fired brass to get as close a fit as possible to the previous guy's gun, which meant I set it around go+.003. Then I try to size right around .002-.003 shy of that original case, which is now functionally identical to a case fired from my gun. And you can tell when closing the bolt if you're even one or two thousandths off, longer or shorter. .002 seems to be an amount you can just not quite feel in the bolt, so I feel like that's part of why it was picked.

So I do all that prep work that makes me feel like I know something, and then I go and lube unevenly, get stuff caked on the press, have die die wander on me, and only get about half my cases within one thou of the target. Some are bumped by .012, .008, .000. Some are longer somehow. Then I get really nervous and waste a lot of time fussing around trying to diagnose and fix.

Then they all shoot into the same .3moa hole without fail.

I think the concept is sound especially at longer ranges, and the idea of working the brass less and generally having fewer variables is certainly good, but the likelihood you're missing something is low. Any FL sized case is going to be MUCH closer to chamber size than new brass or factory ammo. A basic FL size in accordance with the instructions that come with the cheapest die set is going to be a very good fit. Better is always a good thing, but driving yourself bananas isn't.

 

[cantfixstupid]

I use my chamber and the Redding competition shell holders to do it. Has served me well.

What he said since I got the Redding shell holders, its set it and forget.

 

[Varmint Hunter]

If a fired case can easily be rechambered; why bump back the shoulders at all?

Hmmmmmmmmmmm

 

[spladi]

If a fired case can easily be rechambered; why bump back the shoulders at all?

Hmmmmmmmmmmm

Uniformity of all the reloads would be a reason but a prerequisite would be to measure all cases before FL sizing to check the variation from case to case, some may be too short if not originally fired in the chamber being used.