Concentricity Question/Help

[MikeMcCasland]

For a while now I've been using typical F-Class reloading procedures and equipment, but never really wanted to "waste money" on a gauge that would probably sit unused. I'd read a lot of threads about folks buying gauges, but never using them after the first month or so.

That said, following a conversation at a match this weekend, I picked up a 21st century concentricty gauge and finally got it in today. I eagerly started running brass and loaded rounds alike through it, and found a problem.

I had some leftover .308 rounds from a MR match, and tossed them on the gauge. Looks like case neck TIR was ~.003-.004 (not great, but I'd guess it's expected with a Type-S die). Unfortunately though, my loaded bullet TIR was .006-.009...definitely not ideal, and very visible with the naked eye.

For seating I'm using a Forster Micrometer/Comp seater, and I'd been shooting 195 TMKs in F-T/R. I figured there was a chance the long tip made contact with the stem, so I just seated some relatively stubby 175 SMKs and appear to be getting the same thing.

I guess my question is, does bullet TIR directly correlate to neck concenctricity, or do I just have a problem with my seater? Seater is setup correctly, and I diassembled/cleaned/lubed it before trying those 175s..no change. I don't have any other .308 dies to test with unfortunately, and the only thing .308 based is .260 Redding gear.

Any thoughts/ideas/suggestions?

Pertinent Info:
Press RCBS RC Supreme/Redding comp shell holders
Brass: .308 Lapua Palma 4x fired.
Chamber: 2013 FTR .308 on a SPR/bugholes smithed bartlein

BTW Jim - If you read this, you were right. I think I'm going to give a Whidden FL sizer a try.

Thanks in advance!
Mike

 

[Uncle Ed]

I measure my case neck runout after sizing and bullet runout after seating. And this tells me where the runout is coming from when troubleshooting.

Also with a bushing die when you reduce the neck diameter .004 or more it can induce neck runout. And if you do not turn the necks the Redding bushing FAQ tells you if the neck thickness varies more than .002 to use the expander that comes with the type S bushing dies.

Bottom line, bushing dies work best with tight neck chambers and neck turned brass.

And the reason so many reloaders use a body die and a Lee neck sizing collet die is because they produce less neck rounout than a bushing die in the average chamber.

I use Forster full length benchrest dies with their high mounted floating expanders. And these dies give me far less bullet runout than bushing dies, and I only size the case once.

 

[ballisticdaddy]

I believe both the sizing and seating dies are both suspect to inducing TIR. After going through this dilemma myself I purchased the same gauge and found anywhere from .0005 to .0045 TIR on my loaded rounds. Then chased my tail trying quite a few different die combos but ended to going with a basic Redding full length sizing die (honed to my desired neck diameter) and a Wilson in line seating die and was able to get the maximum TIR down to .001

 

[varget204]

Yes ,neck runout is not good.Your fired cases should be under .001,the more you get in the neck case the more you'll have in loaded round,.003 is about max,hunting rounds are normally .003-.005. .006-.009 is way too much.Have seen shooters cut their groups in Half with concentric ammo.I would take a couple of fired cases,remove,bushing and decap rod, and size.Measure how much run out,i also would rotate die a little and repeat,see if RO gets less,would do same with decaping rod,to see if it lessens.Many people use a sizing mandrel to eliminate expander button.I use Hornady Custom Match Bushing dies,fired cases,a few are off .001-thats .0005 a side,almost all my loaded round are .001 or less,a few .0015,any thing loaded over .0015 is used for warm up or spotter round.Have also had good luck w/ RCBS Gold Medal Match bushing neck and FL dies,I check every case after resizing,some cases i rotate case 180 degrees and resize,i do that on every shell that is seated.You have to check your dies,Every brand sends out some stinkers,i have a high$$ Redding Competition Neck sizer,when you resize new .000 run out lapua cases,they come out .002 off,sent back was told that was w/in specs,never bought another.Hope this helps

 

[MikeMcCasland]

I don't have any 'fired' cases; all this brass has been annealed/sized/primed/trimmed etc. They're basically ready for powder and a bullet.

I've read before where it's fairly normal to get .003 neck runout using a bushing die, so I'm not too worried about that at the moment (obviously I'd like better, but I can live with it for now). I am concerned about the .006-.009ish runout on a seated bullet.

It's also interesting too, because in that MR match, this load shot like absolute crap, whereas right before it was running them into the same hole.

 

[dstoenner]

For lowest runout I use Forster full length dies honed and no expander. All of my brass (340 lapua cases) was all neck turned at the same time. I am doing a .003 neck size so with spring back it is .002. A run of 100 cases gets 70 or more that are .001 or less runout. The rest is .002 with a few .003. This is for my 6 br and my 6x47L which I shot in F-class. For seating I use a Redding Competition seater with vld stem. I will get loaded runout at 55% or so with the rest .002 and again a few 3’s for good measure.

I think this all really counts in midrange but I am still learning about wind at 1000 so I cannot tell for sure how much difference it makes.

Uncle Ed was right that you have to have good cases going into seating or you don’t know what is happening. Take some cases you have .001 runout on and then seat some bullets. If you get no .001 then there is your problem. If you get 50% or more then seating is not completely the issue.

Reloading is a lot of trial and error for a personal process that works for you

David

 

[T-shooter]

Many times runout is caused by the case. The picture shows examples (way overdone for effect). I use Forester BR dies and a Redding Micrometer seater. I've had new cases that is was impossible to get the runout out of until they were annealed and resized again. They would just spring back after resizing. The bottom example is a neck that is not centered with the case body. I had a couple hundred Hornady .308 Match cases that were this way and they would average about .007" runout. After annealing and resizing, most were under .001 with a few as high as .003"



I usually check runout on the bullet about 1/2 way between the tip and where the ogive/bearing surface intersects.

 

[T-shooter]

I've used the Forster die with and without the expander ball and can tell no difference. It's probably more the way you use one than if you use one. My die has been honed by Forster and it sizes to make the case about .003" undersize and I let the ball bring it back to size. I set the ball as high as possible on the stem without it locking up the die. This way most of the neck is still in that part of the die when the ball is pulled through keeping it centered and straight. Run a case completely into the die and then unscrew the stem/ball until you feel it touch. Then turn back down about 1/2 turn. The stem on the Forster can move and self-align if necessary as it's pulled through. I added an extra nut so I could lock the spindle to the spindle locknut.

 

[MikeMcCasland]

Found a few cases with .001-.0015 runout, and seated them; still got .006-.007 bullet runout (measured just slightly ahead of the ogive). Figure something is screwy with the seater. I pulled the stem out and tried to measure that; looked like it only had .0005 variance, did the same for the sleeve, and it seemed fine.

I just ordered a Whidden standard FL sizer, the carbide expander kit & Micrometer seater. I'll call Forster tomorrow to try and RMA this seater.

 

[papajoe222]

I second checking after sizing and again after seating. I found out the hard way that insufficient lube on the inside neck was the culprit of my woes.

 

[Dusty Stevens]

check each step to find the culprit

 

[rwj]

Curious to know if concentricity gauge users have a standard, like a gauge pin, that they use to check the accuracy and repeatability of their measuring system?

 

[butchlambert]

Curious to know if concentricity gauge users have a standard, like a gauge pin, that they use to check the accuracy and repeatability of their measuring system?

To my way of thinking a gage pin would show nothing as I've never seen a cam shaped gage pin. The way the checkers are made it is a little hard to see how it would affect the concentricity of a gage pin. Am I missing something?

 

[Alex Wheeler]

Only a possible issue if the case spins on rollers.

 

[butchlambert]

I know this was touched on, but the first check would be on a fired round before anything has been touched on the brass. You need to eliminate a chamber problem first.
I make my own PPC full length die and seater. My sizing die reamer is spec'ed .002 under at the shoulder and .003 at .200" above the base of the rim. I made my own micrometer seater die with my chamber reamer. A loaded round will be at no more runout than .001 Pictured below is my seater.

The stem is ground on the OD and fits the reamed hole in the die.

 

[butchlambert]

Only a possible issue if the case spins on rollers.

I agree with that, but would wonder why somebody would use bearings instead of gage balls.

 

[Nature Boy]

I was checking every loaded round for runout but decided recently to quit doing it.

I’m using Widden FL mandrel dies. One set for my .308 was honed to fit fired cases, the other set for my 6BRA was honed to the reamer print. I’m loading these on a Dillon 650.

Shot a 600 yard F Class match last weekend. Here’s the first target of the day. 5 sighters and 20 for record all inside the 10

Ended the day with a 600 - 36X

What was my TIR on these rounds? Hell if I know and now I really don’t care.

 

[MikeMcCasland]

I was checking every loaded round for runout but decided recently to quit doing it.

I want to be clear; I have no intention of checking every single case/loaded round, assuming they come out of the dies relatively consistently. I'd be fine with .003-.004 of TIR, because I think you're likely splitting hairs at that point.

My thought is that managing concentrictiy only matters if you're out of spec beyond a certain point. That said, what I was seeing spinning .308 cases (.006-.009) has to be beyond that point, and cannot be conducive to accuracy.

What's interesting is that I use (correctly setup) Redding bushing dies for every bolt gun cartridge I load for, and they all seem to put a little bit of run out in the case neck; some better than others. That said, for my ARs I've just been running them into cheap/standard RCBS FL dies w/o an expander, and mandrel expanding them back up. Those seem to have the least runout of anything. Go figure.

I've got my Widden dies on order, and will be shooting all this brass on Saturday to get them all back to square one for troubleshooting. For the rest of my calibers, I'm just going to tinker with the bushings/bushing looseness etc. to see if I can't reduce TIR. That said, I'm building up a custom to 'get serious' in F-T/R in the coming months, so would like everything as close to perfect as possible for that rig.

For those of you reading this who hadn't pulled the trigger on one of these gauges...the results may be more interesting than you think...even if you're using relatively decent dies/equipment.

 

[rwj]

To my way of thinking a gage pin would show nothing as I've never seen a cam shaped gage pin. The way the checkers are made it is a little hard to see how it would affect the concentricity of a gage pin. Am I missing something?

I’m thinking that a gauge pin should indicate virtually zero TIR. If it doesn’t, one would have to suspect that there are sources of inaccuracy in the gauging system. They include the components that comprise the system and the user that is manipulating the workpiece...

 

[T-shooter]

Found a few cases with .001-.0015 runout, and seated them; still got .006-.007 bullet runout (measured just slightly ahead of the ogive). Figure something is screwy with the seater. I pulled the stem out and tried to measure that; looked like it only had .0005 variance, did the same for the sleeve, and it seemed fine.

I just ordered a Whidden standard FL sizer, the carbide expander kit & Micrometer seater. I'll call Forster tomorrow to try and RMA this seater.

Where are you measuring the case and bullet runout? I measured 3 rounds in various places to see what the differences were using a Sinclair concentricity gauge and a 1/2 thou dial indicator (estimating some of the readings) and checking each several times. The necks were turned on 100% of the surface. On #7, I used a seater insert and modified the gauge to read from the tip of the bullet like a Hornady gauge.