How much OAL variance are you guys seeing in 9mm?

[Steve RA]

Yes, however we are discussing thousandths of an inch, and the average deviation won't really make much difference in the operation of the average semi auto.  It can have an effect on ultimate accuracy if that is your primary goal.  In the average competition setting the primary goal is just to have each round fire and extract properly.

[BeerBaron]

what RDA is saying about the ogive affecting OAL is correct but I'd amend it slightly to say the ogive MAY be contacting the seating stem. many type of bullets will contact the tip of my fairly flat lee seating stem. 

 

best bet if you are interested is pull the seating stem and see for a given bullet does it contact the ogive or the tip?

[RDA]

On 2/16/2017 at 7:41 PM, BeerBaron said:

what RDA is saying about the ogive affecting OAL is correct but I'd amend it slightly to say the ogive MAY be contacting the seating stem. many type of bullets will contact the tip of my fairly flat lee seating stem. 

 

best bet if you are interested is pull the seating stem and see for a given bullet does it contact the ogive or the tip?

 

Agreed, depends on the seating stem and bullet profile, I was avoiding being too comprehensive on the topic based on the discussion to this point and speaking to the most common scenario.

Edited February 28, 2017 by RDA

[jakfrost1]

I too was wondering how variation in the brass length could affect the COAL...but was too shy to point out that it would seem obvious that there is no way it could. You are measuring from the base of the brass, ( below the headstamp, obviously...), to the tip of the projectile, ( not the ogive...) and as long as the brass is long enough to encase a portion of the projectile and hold it, your seating die will always push down the same distance and the COAL 'should' be the same, no matter how long or short the brass is. Of course there are many other factors as others have pointed out, but case length isn't one of them. 

I just discovered that the 'seating stem' in my Dillon die is reversible, ( first progressive, first Dillon, learning curve goes up a notch...), and by using the 'flat' end instead of the 'round' end, ( loading Zero 125 jacketed HP's ), my variance went from over .01" down to .002-.005". Light bulb moment. 

[Sarge]

5 hours ago, jakfrost1 said:

I too was wondering how variation in the brass length could affect the COAL...but was too shy to point out that it would seem obvious that there is no way it could. You are measuring from the base of the brass, ( below the headstamp, obviously...), to the tip of the projectile, ( not the ogive...) and as long as the brass is long enough to encase a portion of the projectile and hold it, your seating die will always push down the same distance and the COAL 'should' be the same, no matter how long or short the brass is. Of course there are many other factors as others have pointed out, but case length isn't one of them. 

I just discovered that the 'seating stem' in my Dillon die is reversible, ( first progressive, first Dillon, learning curve goes up a notch...), and by using the 'flat' end instead of the 'round' end, ( loading Zero 125 jacketed HP's ), my variance went from over .01" down to .002-.005". Light bulb moment. 

There is no getting around the fact that different headstamp brass produced different length ammo. I don't know why nor do I care enough to figure it out. It just does

[lgh]

1 hour ago, Sarge said:

There is no getting around the fact that different headstamp brass produced different length ammo. I don't know why nor do I care enough to figure it out. It just does

 

That has also been my experience. OAL variation is just a fact of life.

[Hupperware]

Very little when using round nose... .005ish when using JHP

[Dr Mitch]

None

[MemphisMechanic]

13 minutes ago, Dr Mitch said:

None

I'm going to need video of you mic'ing rounds in order to believe this.

[Dr Mitch]

I don't mike anything.  I use certified calipers, or what some machinists call guess-o-meters.  Reloading to under a thou variance using mixed range brass is easy.  Control the variables by working like an actual professional.  Set your press up like you expect it to produce high-margin (>20% minimum) revenue for 10 years.  It is ridiculously easy.

[MemphisMechanic]

I've never found anything I could do on a 650 to reduce OAL variation to less than .005" using mixed brass. Nothing in my operation or in press setup would get under that margin, not even clamping down the toolhead and running a very tight bearing on the shellplate bolt.

 

Since I was getting sub-2" at 25 yards with ammo that had .008-.010" of OAL variation I eventually decided there really wasn't a point in trying to produce 'perfectly consistent' ammo. However, I'm curious how you manage to do so without a machine-operated press.

 

Edited June 2, 2017 by MemphisMechanic

[lgh]

9 hours ago, Dr Mitch said:

None

Dr.Mitch - That is not possible. Do an error analysis. Measure brass and bullet length, variations in your reloader, calipers, etc., etc. If you do not see variation, you are not doing your OAL measurments accurately.

[candiru]

I've never found anything I could do on a 650 to reduce OAL variation to less than .005" using mixed brass. Nothing in my operation or in press setup would get under that margin, not even clamping down the toolhead and running a very tight bearing on the shellplate bolt.
 
Since I was getting sub-2" at 25 yards with ammo that had .008-.010" of OAL variation I eventually decided there really wasn't a point in trying to produce 'perfectly consistent' ammo. However, I'm curious how you manage to do so without a machine-operated press.
 

Indeed. Hell, I did the OCD thing and did batches of ammo on a Forster Co-Ax with Redding dies and couldn't eliminate the OAL variation using mixed brass and a variety of different bullet manufacturers.

There are inconsistencies in the bullets' total length vs length to ogive. Expensive bullets generally were a lot more consistent than cheaper.

But as long as the oal fits your magazines and feeds well, length to ogive is what actually matters. Try measuring that and you should find the numbers being much more consistent.

[9x45]

11 hours ago, Dr Mitch said:

None

 

Really? All Dillons throw about +/- .005" for AOL. What calipers are you using? What press? What bullets? What brass?  Whats the reading on this vernier micrometer?  A "thou" is .001", not .010"..... That would be "ten thou" and no auto progressive ever made would exceed that for OAL.

 

 

 

Edited June 2, 2017 by 9x45

[DWFAN]

Using pre-prepped single headstamp (starline) brass, and Zero 115 JHP, I get +-.001 (over 100 rounds) from my Ammobot equipped 1050, Hornady seating die, redding crimp.

 

 

[mikeinctown]

I get a swing of about .005-.007 which is really next to nothing on a bullet with a baked on polymer coating. At first I thought something was wrong with the way I was working the press, but then I saw the shellplate flex ever so slightly depending on if the case in the size die had more or less lube. That affected the bullet seating station as it was on the opposite side of the press. So unless you have a shellplate that rotates with .000 of variation when force is applied, you will never have zero.

[mjmagee67]

Mixed brass with coated bullets I'd say 95% fall within +/-.003 and the other 5% within +/-.005. Which is just fine for a USPSA pistol round. As a matter on note....with mixed brass I regularly get SD's in the mid teens. With single manufacture brass I regularly see SD's in the high single digits. All SD's are over 10 to 20 shot strings and my best SD I've seen was 3.8 over 14 shots, that load was FC brass, 125gr Leatherhead Bullets, Fed SPP, 4.1gr VV N320 at 1.115 OAL with a 131PF.

[Want2BS8ed]

Using pre-prepped single headstamp (starline) brass, and Zero 115 JHP, I get +-.001 (over 100 rounds) from my Ammobot equipped 1050, Hornady seating die, redding crimp.
 
 

That's impressive. New Starline brass and a Precision Delta 147g TC on a Mark VII equipped 1050 I'm experiencing an extreme spread of ~.005", which I always thought was pretty decent considering I'm seating and crimping in the same station to retain a powder check.

M