(embarrassing) question about Redding bushing dies - .004" discrepancy. Annealing?

secondofangle2

Online Training Member
Full Member
Minuteman
Jul 3, 2017
853
472
I'm embarrassed I'm so confused about this; hopefully somebody can help me understand. I'm reloading Hornady Match 308 brass. 7th firing, tumbled clean with corn cob, annealed on AMP. Necks not turned. Shot out of a DT barrel, standard chamber. I'm using .332 bushing (I haven't reloaded .308 for a few years, I had a stockpile reloaded - I presume I have the .332 in the die for a reason, but I don't have notes. I generally have aimed for .001-.003 of "neck tension".) Cased lubed with Hornady one shot. Modest force required for sizing in the die. When the case comes out of the Redding Type S die with .332 bushing, the neck measures .328" OD with Starrett caliper; repeated measurements over and over; no force applied to calipers, measured delicately. When a bullet is seated, light force on the press arm is required to seat - seats "easily", like I think about .001-.002" tension would be, not .004" tension. With bullet seated, the neck OD measures .332". A sized case can be manually inserted into the bushing (removed from die) with mild-moderate force and the case can be rotated 360 degrees in the bushing manually - so it's tight in there and the "tightness" is uniform during a 360 degree rotation. If there were .004" clearance, I would think I could wiggle it in that bushing. A loaded round will not fit into the bushing at all - not even close.

So why the heck are my necks measuring .004 smaller (.328") than the bushing I'm using (.332")? For the life of me I can't figure this out, but I wonder if annealing isn't part of the equation. I'm tempted to buy a .333 & .334 bushing

Thoughts?
 

secondofangle2

Online Training Member
Full Member
Minuteman
Jul 3, 2017
853
472
about .329" ID of the bushing, however as you know the calipers have a flat not a radiused surface.

Can they be that far off? 0.003" sounds like a lot!

puts me in a bind also for deciding on what size to increase too if you can't depend on the advertised measurement.
 
Last edited:

morganlamprecht

Sergeant
Full Member
Minuteman
Nov 5, 2013
1,560
1,780
bushing size could be wrong, but you also have to consider brass size/rigidity prior to sizing if youre wanting to hit a specific size

example i remember is my 223 die at home...

if i fire a 223 round, the neck comes out like .260 (cant remember this number exactly, but its quite a bit larger than the bushing size range)

if i size said brass, straight away with a .248 bushing, the brass neck will come out at .245...

if i size the brass down to .252, then .248, it comes out spot on .248, with the same .248 bushing used the whole time

brass type/age/annealing effects will change these numbers slightly, but iirc, any sizing down steps greater than ~.005-006" with my bushing dies, typically caused some undershoot in intended neck diameter

also when I would get the undershoot, typically the very edge of the mouth will be slightly larger than the rest of the neck, so you can check it visually for any small amount of bell in the case mouth

i saw the same w/ 308, 6.5prc, and 6.5creed...after those 4 examples i just started factoring it in
 

secondofangle2

Online Training Member
Full Member
Minuteman
Jul 3, 2017
853
472
I just measured my 338 LM; Lapua brass. .365" bushing measures .363" inside but I think that's error from the caliper flats. It sizes AMP annealed brass to .365 and a loaded round is about .3665-.367
 

secondofangle2

Online Training Member
Full Member
Minuteman
Jul 3, 2017
853
472
It may have something to do with the annealing. I was wrong about AMP annealing I annealed these on the giraud. I removed a bullet from one of these dummy rounds and expanded neck with mandrel and re-resized it and bingo - it's .332 now. I then annealed on the AMP and repeated this and .332 again. So maybe I was under-annealed on the Giraud? It was Tempilaq tested and should have been close. I'm confused.
 

Lawnboi

Gunny Sergeant
Full Member
Minuteman
Sep 30, 2019
576
464
WI
Your using the wrong tool for the job, re measuring.

Get a few pin guages, select the bushing that gives you your preferred neck tension.

Too many things can change spring back in your brass to be able to nail down what’s going on exactly. A pin guage will tell you if anything is changing firing to firing.
 

Lawnboi

Gunny Sergeant
Full Member
Minuteman
Sep 30, 2019
576
464
WI
can you recommend a set of pin gauges?
K&m carries some. They are made by various gauge companies but that’s what Iv been using.

Forester just came out with a cool stepped gauge thing but I can’t bring myself to spend that kind of money on the set.

As noted, brass changes. Pin gauges can keep you consistent through firings and any changes in your process.
 
  • Like
Reactions: secondofangle2

918v

It’s not the primer!
Full Member
Minuteman
Jul 15, 2007
5,886
3,093
Miserable CA
I'm embarrassed I'm so confused about this; hopefully somebody can help me understand. I'm reloading Hornady Match 308 brass. 7th firing, tumbled clean with corn cob, annealed on AMP. Necks not turned. Shot out of a DT barrel, standard chamber. I'm using .332 bushing (I haven't reloaded .308 for a few years, I had a stockpile reloaded - I presume I have the .332 in the die for a reason, but I don't have notes. I generally have aimed for .001-.003 of "neck tension".) Cased lubed with Hornady one shot. Modest force required for sizing in the die. When the case comes out of the Redding Type S die with .332 bushing, the neck measures .328" OD with Starrett caliper; repeated measurements over and over; no force applied to calipers, measured delicately. When a bullet is seated, light force on the press arm is required to seat - seats "easily", like I think about .001-.002" tension would be, not .004" tension. With bullet seated, the neck OD measures .332". A sized case can be manually inserted into the bushing (removed from die) with mild-moderate force and the case can be rotated 360 degrees in the bushing manually - so it's tight in there and the "tightness" is uniform during a 360 degree rotation. If there were .004" clearance, I would think I could wiggle it in that bushing. A loaded round will not fit into the bushing at all - not even close.

So why the heck are my necks measuring .004 smaller (.328") than the bushing I'm using (.332")? For the life of me I can't figure this out, but I wonder if annealing isn't part of the equation. I'm tempted to buy a .333 & .334 bushing

Thoughts?

Assuming the id of the bushing is .332”, it is not unusual for the middle of the neck to come out smaller than the case mouth or the bushing id. It’s the way the neck extrudes though a constriction. A proper diameter mandrel corrects this.
 
  • Like
Reactions: fxdrider

M.A. Matteson

Private
Minuteman
Mar 8, 2021
9
1
Murrieta, California
Normally annealing is done before sizing the brass. The other is you can cut the necks for thickness from a new case to start with. If fired then you need to size the neck and use a mandrel to push the uneven parts of the neck to the outside to cut for thickness. The other way is to undersize the neck and then use a mandrel to push the neck out so it's round inside the neck. Uniformity are to the outside. With that you haven't gotten by the uniformity even then. At time of firing the round the uniformity hit uneven in the chamber pushing the bullet to one side or the other. So you haven't gain anything. There to it than that. Cutting the necks for thickness. 1. trim your case to all the same length. 2. Set up the stop to just touch the transition at the neck to shoulder. DON'T CUT THE SHOULDER. Proper mandrel to fit the I.D. of the neck. Use a dry lube for the inside of the neck to turn the case.
I use Redding bushing dies. With the necks cut for thickness, I don't or haven't had a problem in setting up my neck tension yet.
 

Cascade Hemi

Major Hide Member
Full Member
Minuteman
Feb 9, 2019
1,609
1,410
PNW
About 50% of my Redding bushings are the incorrect size. Some by a lot, some by only a little. SAC bushings are a much better alternative.
 
  • Like
Reactions: reubenski

reubenski

Supporter
Supporter
Full Member
Minuteman
Supporter+
Jun 8, 2008
6,993
7,778
To
I'm embarrassed I'm so confused about this; hopefully somebody can help me understand. I'm reloading Hornady Match 308 brass. 7th firing, tumbled clean with corn cob, annealed on AMP. Necks not turned. Shot out of a DT barrel, standard chamber. I'm using .332 bushing (I haven't reloaded .308 for a few years, I had a stockpile reloaded - I presume I have the .332 in the die for a reason, but I don't have notes. I generally have aimed for .001-.003 of "neck tension".) Cased lubed with Hornady one shot. Modest force required for sizing in the die. When the case comes out of the Redding Type S die with .332 bushing, the neck measures .328" OD with Starrett caliper; repeated measurements over and over; no force applied to calipers, measured delicately. When a bullet is seated, light force on the press arm is required to seat - seats "easily", like I think about .001-.002" tension would be, not .004" tension. With bullet seated, the neck OD measures .332". A sized case can be manually inserted into the bushing (removed from die) with mild-moderate force and the case can be rotated 360 degrees in the bushing manually - so it's tight in there and the "tightness" is uniform during a 360 degree rotation. If there were .004" clearance, I would think I could wiggle it in that bushing. A loaded round will not fit into the bushing at all - not even close.

So why the heck are my necks measuring .004 smaller (.328") than the bushing I'm using (.332")? For the life of me I can't figure this out, but I wonder if annealing isn't part of the equation. I'm tempted to buy a .333 & .334 bushing

Thoughts?
Redding bushings are often incorrectly sized. But here's the question. Does it matter? How do they shoot?
 
  • Like
Reactions: DIBBS

secondofangle2

Online Training Member
Full Member
Minuteman
Jul 3, 2017
853
472
Redding bushings are often incorrectly sized. But here's the question. Does it matter? How do they shoot?
I tested the bushings with pin gauges. They are correctly sized.

It matters because if I'm setting stuff up year after year, I want to be able to measure to make sure stuff was set up the same as last time. If there are inconsistencies between numbers, it can get confusing.
 

reubenski

Supporter
Supporter
Full Member
Minuteman
Supporter+
Jun 8, 2008
6,993
7,778
To
I tested the bushings with pin gauges. They are correctly sized.

It matters because if I'm setting stuff up year after year, I want to be able to measure to make sure stuff was set up the same as last time. If there are inconsistencies between numbers, it can get confusing.
I would argue this exact situation is a lot like the seating depth and bullet jump argument. Doesn't matter if you know exactly where your bullet touches the lands or does it matter that you know a specific CBTO that shoots well? The latest trend is a large group of people who will say it doesn't matter that you know the absolute measurement. It really just matters that you know at what overall length to seat your bullets. So likewise does it matter if what you're loading shoots well? Just keep using the bushing if the bushing produces good results.

Maybe my answer is the above because I just lack the willpower to try to walk people through troubleshooting steps on magic 8-ball problems on the internet. It's almost always fruitless because you never really know it's going on on somebody's loading bench.
 

fxdrider

Deplorable
Supporter
Full Member
Minuteman
Jan 3, 2014
683
420
Fredericksburg, Virginia
Excerpt from Redding Tech Line & Tips: Bushing Selection

"It has come to our attention through customer calls and our own use of the bushing style sizing dies that in certain instances, a given neck sizing bushing will produce a case neck diameter that can be several thousandths of an inch smaller than the actual diameter of the bushing. This idiosyncrasy occurs when the neck diameter of the fired case is a great deal larger than the diameter of the neck sizing bushing, such as occurs when factory chambers are on the large side of the tolerance range and the brass is on the thin side. Typically, we have not noticed any problems until the case neck is reduced more than 0.008-0.010".


Solutions include, increasing bushing diameter to compensate and/or the use of a size button. Reducing the neck diameter in two smaller steps by using an intermediate diameter bushing will also help. More concentric necks will also result using this method, as the case necks are stressed less during sizing. Don't forget to properly chamfer the inside and outside of the case mouths and apply a light coating of lubricant to the case necks before sizing."

Tech Line & Tips (FAQs) Bushing Selection