Bumping a shoulder

[Retro]

OK, I understand the science behind wanting to do this but I don't understand how to do it physically. Yes, I know that in principal you are wanting to move the shoulder back a few thousandths. Once you install your sizing die, have it touching the shell plate, then 1/4 turn in to take up any flex where are you actually getting the additional bump? I'm having trouble with the physics of it after the die is seated. I know that when I first started reloading I didn't have the die down far enough and had a whole batch of FTF but once I set the die properly I've never had that problem again. If one or two or however many of the horde can enlighten me I would appreciate it.

[LR1955]

OK, I understand the science behind wanting to do this but I don't understand how to do it physically. Yes, I know that in principal you are wanting to move the shoulder back a few thousandths. Once you install your sizing die, have it touching the shell plate, then 1/4 turn in to take up any flex where are you actually getting the additional bump? I'm having trouble with the physics of it after the die is seated. I know that when I first started reloading I didn't have the die down far enough and had a whole batch of FTF but once I set the die properly I've never had that problem again. If one or two or however many of the horde can enlighten me I would appreciate it.

Retro:

You finally had the sizing die down far enough to bump the shoulder. Not sure what the question is. Yes, you did push the brass farther into the sizing die, thus pushing the shoulder back enough so the brass would chamber and extract easily. Basically, you created a situation where the brass was sized down enough to headspace properly with the chamber.

LR55

[Clarence]

Retro,

Dies are designed to bump back a shoulder to minimum headspace (or further) when set up the way you indicated. However, that may be more bump than you want, creating a situation where you can get excessive stretching.

Here's the procedure I use:

First, to do this right, you really need one of the various tools to measure the distance from the base to the datum on the shoulder on a fired case.

With the press ram up, screw the die until it touches. Lube and size a case; measure the distance from the base to the datum. You are shooting for 0.002-0.004" less than the first measurement.

Adjust the die slightly further down if you haven't bumped the shoulder enough. One full turn of the die represents 0.071", so it doesn't take much. I suggest marking both the die and lock ring-each thousandth requires moving the die ring ~0.040". It can get tedious; I have a set of shims I purchased from Sinclair, and it's easier for me to set the die for a little too much (like 0.005") shoulder bump, and then use shims to get exactly what I want.

Remember that different brands of brass will spring back differently, so may need a slightly different adjustment, and annealed brass will spring back less, requiring different adjustment.

Hope this helps. It takes some effort, but will reward you with longer brass life if done properly (in addition to improving reliability, as you found).

Clarence

[FW Conch]

So was the FTF the result of Fail to Chamber?

[Djamiller]

Is there a specific tool you recommend? I never did this before but I've never had a problem with 223. Not sure if I got lucky or what. My colt seems to eat EVERYTHING without fail.

[204 AR]

Here is what I use:

http://www.midwayusa.com/product/479704/hornady-lock-n-load-headspace-gauge-5-bushing-set-with-comparator

I did it the hard way for years and years, just trial and error with the rifle, size, chamber, size a little more, chamber, repeat until the case just chambered and extracted easily. With this bushing set, you can measure the distance to the shoulder of a case fired in your rifle, then adjust your sizing die until you have just pushed the shoulder back the amount you want. I shoot for 4 thousandths on my stuff as I shoot suppressed and the chambers get pretty sooty, and I don't want any malfunctions while hunting.

[2_speed]

In most cases, its best to use the same brand of shell holder as the sizing die, too. There can be some small differences if you "mix & match".
Tom

[lwminton]

Is there a specific tool you recommend? I never did this before but I've never had a problem with 223. Not sure if I got lucky or what. My colt seems to eat EVERYTHING without fail.

Get this tool and never look back. You will use it all the time. The 6mmPPC version works with the Grendel case, but double check with Redding to make sure they haven't done a newer Grendel version). Then measure a case that has been fired a few times which is a good estimate of YOUR chamber. Set up the sizing die according to instructions and measure the sized case. The difference will probably be greater than .003-.004 so back the die out until you get the set back you want. For an AR I use .004-5. With this tool, you will check the set back all the time so it won't get away form where you want it. I put mine in a T7 and never touched it since.

http://www.brownells.com/reloading/measuring-tools/case-gauges-headspace-tools/6mm-ppc-instant-indicator-prod95385.aspx

[Clarence]

2 speed,

I agree. I measured a Lee and RCBS shell holder, both in .223. Almost 0.005" difference. Regardless of which brand, pick one and keep it together with your dies.

I use the RCBS Precision Mic in several calibers, but it's not available in 6.5 Grendel. I plan to get a Hornady comparator for the Grendel.

Clarence

Clarence

[rothirsch]

Here is the link to the redding tool. This looks like the ticket for

http://www.redding-reloading.com/online-catalog/37-instant-indicator-headspace-and-bullet-comparator

[Clarence]

The Redding tool is nice, if pricy compared to the others, and their catalog does not indicate it is offered in 6.5 Grendel.

Clarence

[Retro]

So was the FTF the result of Fail to Chamber?

Yes. Couldn't get the gun to go into battery. Haven't had that problem since I adjusted the die.

[Retro]

Thanks for the info. I actually have a much better understanding now. I've been using an LEWilson case gauge and haven't had the problem with .223 for quite some time now. All the talk about "bumping the shoulders" just got me to thinking and wondering if there was something that I wasn't doing that I should be. I guess the take-away for me is that I don't necessarily have to have the die set to max contact with the shell holder if my cartridges are chambering OK. I have a Sheridan gauge for my Grendel. I actually like it better than the Lewis gauge. I don't mind screwing up a little .223 brass as it's easy to find at the range. I don't want to screw up the Grendel brass as it's never on the ground and it's expensive.

[lwminton]

The Redding tool is nice, if pricy compared to the others, and their catalog does not indicate it is offered in 6.5 Grendel.

Clarence

The II tool does not have to be "made for" the Grendel. It only has to fit over the neck and sit on the shoulder. All you want is a number for fired brass and sized brass - then subtract. Read Zediker's book. The accuracy and ease of the II tool is worth every penny. You will use EVERY TIME you reload and it takes seconds compared to farting around with a caliper and all the errors you get from attaching and reattaching. You spend thousands on your rifle and you want to save 50 bucks on an imperfect tool?

[IceAxe]

One thing I would add is to measure some of your fired cases with the comparator and average them to determine your starting point.