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Phlier

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

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So I have around 12,000 rounds through my 1050 now, and am quite happy with how it's finally running... That is, until last night.

I only load .223 and 9mm on it, and this concerns 9mm...

My favorite 9mm recipe is a 115gr fmj loaded to 1.125 OAL. Until last night, I was getting 1.22 on the low side, and 1.127 on the high side. But those are the outliers. Most all of them fell within 1.123 to 1.126. "Most" as in 90%. This is using mixed head stamp range brass, which is what I always load... I don't bother to sort 9mm by head stamp.

Last night, I ran out of my 115gr fmj's, and had to switch to a 115gr plated. I measured the first five off the press. First one was 1.120, then 1.119, 1.120, 1.118, 1.120. This length is acceptable for this load, so I proceeded to load up the shell plate so I could measure the next five "production" rounds with a full shell plate. Results were very similar. I never had to touch the bullet seating die to get these results. So I ran off a hundred.

At the end of each 100 loaded, I check the OAL of the last five cases produced (as well as run other sanity/safety checks that aren't relevant to this discussion). I noticed that the variance from shortest to longest loaded round had increased a bit, but was certainly still acceptable.

Trying to shorten a long story...

By the end of the night's production (1.2k loaded rounds) I had tried everything I could think of to solve a rather large variance (which continued to increase as the night went on) in OAL. I was now getting a low of 1.110 and a high of 1.120. So overall, the cases average OAL shortened quite a bit. (1.10 is the bare minimum acceptable length, so I'm still ok as far as that's concerned). I now had a variance of one hundredth of an inch! I've never seen such extreme variation in loaded round length from this press!

What in the world is causing my previously tight OAL tolerances to go so out of whack?

I've tightened the tool head. It was already as tight as I could get it.

I've tightened the shell plate. It's now as tight as I can get it and still get the thing to auto advance.

I've checked, double checked, then checked again the tightness of the bullet seating die.

OK, so the one tidbit of information I've saved for last... Until recently, I had my own little private collection of 9mm brass. All of the military cases had their primer pockets swaged by me on my rock chucker using an RCBS swaging die prior to me getting my Dillon press.

So I've never bothered to really set up the primer pocket swager on the ten fiddly until last night, as I was recently given a rather large supply of mixed range brass in 9mm. This included a nice assortment of military once fired brass. So, using the instructions from DIllon (along with my primer pocket go-no go gauge), I adjusted the swaging station so that military cases would accept a primer, but no head stamps had their pockets swaged to the point that they wouldn't pass the go/nogo gauge.

Now I can see how setting up this station can cause variance in OAL, as different head stamps (and the condition of their primer pockets) would produce varying degrees of pressure at the swaging station, which is straight across from the seating die. So that's not really a concern. My concern is how the variance *grew* over the course of the night. I also did check to make sure that the case expander/backing die didn't move, nor did the swaging rod adjustments, either.

The variance grew from a few thousandths all the way up to 1/100 of an inch. A variance of 1/100 inch in OAL just isn't acceptable.

I have some more experiments in mind to try and figure out exactly what is causing this, but thought I'd ask for help from you guys, too.

Tonight's experiment will be to sort out 100 non military cases of the same head stamp and load them up without making any changes to the swaging station. Or any other changes to the press, for that matter.

Edit: In addition to any suggestions you guys might have, I'm also interested in hearing  how much OAL variance you guys are seeing in 9mm on the various Dillon Presses? On my Father's 550, I was only seeing a few thousandths.

Edited by Phlier

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My guess is, mixed brass+Swaging+Running shell plate dry+soft plated bullets=higher spread in oal.

The first experiment I would run would be to sort out a hundred of same headstamp , already swaged, and start loading with jacketed bullets. Just pull the handle without slowing down from normal pace. Set aside the first 6 and last 6. Measure all of the others and see if it's tighter.

 

Edited by Sarge

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It is likely that most of the variation you are seeing is caused by variations in the ogive of the projectile.  To test, pull the clip off the seat die, push out the cross pin and remove the bullet seating stem. Hold a projectile up into the stem, and measure from the base of the projectile to the top of the bullet seating stem. Measure 50 or o, and see what the extreme spread is. As an example, I once measured 100 traditional FMJ 9mm 115 grain RN projectiles, of a well-known manufacturer, and found .026" total variation.

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Thanks for the suggestions, gents. I'll follow up with them tomorrow, as the wife kept me away from the press this evening.

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Finally got a chance to crank out some more ammo.

I finished off the plated bullets, and continued to have the same variance in OAL. I received some more FMJ's in the mail yesterday, so I switched to those and loaded up 1k of them. Target OAL was 1.125

Shortest OAL with the FMJ's: 1.122

Longest OAL with the FMJ's: 1.127

Those were the outliers. The majority fell within 1.124-1.126. And that was still using mixed headstamp range brass, including once fired military cases.

It appears that Dillon was correct; the ogive variance in the plated bullet was causing the difference in OAL. It was just a bit of a surprise to me, as I have loaded up that particular brand of plated bullet quite a bit (to the tune of around 10k of them) and had never seen that much of a variance. I did switch from one lot number to another while loading up the plated bullets, and suspect that the second lot number had a lot more variance, hence why the OAL variance "grew" during the course of the loading session.

Still interested to hear what you guys are getting as your "normal" OAL variance in pistol rounds.

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I load 9mm on a 1050 as well and normal  to me is 0.003-4. I took a page out of measuring on the ogive from rifle and actually got a 9mm comparator piece to measure OAL off the ogive in order to verify. There I'm at a 0.001-2 variance with mixed brass.

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I see +/- .003" with both my 550 original and SD. Think it's mostly seating pressure, but it won't matter one bit for action pistol out to 40 yards. Some bullets seat to a tighter tolerance, some dont.

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On 10/21/2016 at 0:07 PM, Sarge said:

My guess is, mixed brass+Swaging+Running shell plate dry+soft plated bullets=higher spread in oal.

The first experiment I would run would be to sort out a hundred of same headstamp , already swaged, and start loading with jacketed bullets. Just pull the handle without slowing down from normal pace. Set aside the first 6 and last 6. Measure all of the others and see if it's tighter.

 

I am not certain what you mean by "Running shell plate dry". About 3/4 through the Dillon video on lubrication, they refer to greasing the shell plate bolt, is this what you are referring to?

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6 minutes ago, Turn11orLarry said:

I am not certain what you mean by "Running shell plate dry". About 3/4 through the Dillon video on lubrication, they refer to greasing the shell plate bolt, is this what you are referring to?

No sorry. I meant not having the shell plate full of cases.

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I seem to be getting a lot of variance seating 9mm bullets in my 650. I'm currently using a Redding Comp die which has the micrometer.

There is a spring between the seating plug and the micrometer. I'm wondering if I may be getting a little bounce out of it as the 650 cycles, causing the excessive deviation.

Any opinions?

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22 minutes ago, MikieM said:

I seem to be getting a lot of variance seating 9mm bullets in my 650. I'm currently using a Redding Comp die which has the micrometer.

There is a spring between the seating plug and the micrometer. I'm wondering if I may be getting a little bounce out of it as the 650 cycles, causing the excessive deviation.

Any opinions?

I was just talking to someone about this today..He had mentioned slop where the toolhead is mounted in the press. He used a feeler gauge to determine the gap and used it as a shim between the two to close the gap. He has very little deviation now.

 

When you say "a lot", what do you mean?

 

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650. Mixed headstamp unknown brass. 9mm. 

 

If I'm setting my press up at 1.150" and find my  ammo measures 1.144" to 1.152" for example...

 

...and they all plunk and spin? I'm taking them to the range, shooting it to ensure I'm satisfied with the accuracy...

 

Then spending my time working on things in my life that actually matter.

 

My gun routinely groups around 1.5" with this variation in my ammo, as did my M&P with an Apex barrel in it.

Edited by MemphisMechanic

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On ‎1‎/‎27‎/‎2017 at 6:46 PM, GringoBandito said:

I was just talking to someone about this today..He had mentioned slop where the toolhead is mounted in the press. He used a feeler gauge to determine the gap and used it as a shim between the two to close the gap. He has very little deviation now.

 

When you say "a lot", what do you mean?

 

I checked this morning and I was seeing .005.

I'm going to try a Whidden tool head that locks down (Uniquetek) on my 550, with a Redding pro seater. I'm expecting less than .002.

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you might look and see if you are getting a build up inside the die - cast bullets are notorious for this, but plated or swaged will do it too- otherwise the OAL cna be varying due to mixed brass.

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if my 9mm ammo all falls within the same 1,000th i'm just fine with that. so if I want them to be 1.125" oal and they all measure anywhere from 1.120" to 1.129" i call it good and don't give it a second thought.

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47 minutes ago, rowdyb said:

if my 9mm ammo all falls within the same 1,000th i'm just fine with that. so if I want them to be 1.125" oal and they all measure anywhere from 1.120" to 1.129" i call it good and don't give it a second thought.

This.

 

My ammo has a standard deviation of less than 10 every time I chrono it. It's good for bagged-in groups of 1.5" at 25yd out of my Tanfoglio. It also varies in OAL as much as Rowdyb's.

 

I see absolutely no reason to chase a reduction in OAL *unless* you take the gun to the range and you can't hit the broad side of a barn.

 

Only two things matter in handgun ammo: consistent velocities so that your ammo stays legal, and it's accuracy. 

Edited by MemphisMechanic

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On 2/4/2017 at 3:41 PM, MikieM said:

I checked this morning and I was seeing .005.

I'm going to try a Whidden tool head that locks down (Uniquetek) on my 550, with a Redding pro seater. I'm expecting less than .002.

 

What type of brass? Mixed or same headstamp? What type of bullets? How consistent are they? Those things will contribute to more of your variance than your 550 in my opinion.

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17 hours ago, RDA said:

 

What type of brass? Mixed or same headstamp? What type of bullets? How consistent are they? Those things will contribute to more of your variance than your 550 in my opinion.

 

Type, or length of brass does not effect OAL. I'm using PD 115's and they tended to stay under a thousandth when measured.

A few days ago I installed a Whidden tool head, with Uniquetek locking screws. The OAL on loaded ammo is now easily within 2 thousandths, with most of it spot on.

Another great thing about this set-up is it really quietened the press down. No more bumping noises when the case is pulled out of the powder measure.

This is on my 550B, by-the-way.

I have a new tool head coming for the 650.

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Just now, MikieM said:

 

Type, or length of brass does not effect OAL.

 

Sure it can.
 

Just now, MikieM said:

 

I'm using PD 115's and they tended to stay under a thousandth when measured.

 

You mean the length of the bullet varies under a thousandth in length when you measure its overall length? That's great, but how well do they measure based on the ogive? Bullet profile consistency is more relevant than consistent bullet length when it comes to COAL consistency (if your concern is simply reducing COAL variance).

 

Ultimately, this fine of variance in pistol cartridges is irrelevant.

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Well, since the OAL is the measurement taken between the case head and the bullet's tip, please tell me where the length of the cartridge case has anything to do with that. 

The ogive of the bullet I use has no relevance to anything because it doesn't change. My concern is the length of the bullet from case head to bullet tip. I have already found that my seating depth will not put the bullet into the rifling, so my only real concern is OAL from a pressure standpoint.

Still, five or six thousandths is not going to make, or break, anything in our kind of shooting, anyway. It's just something to split those hairs a little finer which hand loaders love to do.  

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12 minutes ago, MikieM said:

Well, since the OAL is the measurement taken between the case head and the bullet's tip, please tell me where the length of the cartridge case has anything to do with that.

 

Brass from different makers will result in different bullet seating depths due to variance in case wall thickness.  Also, there is variance in the case rim area between makers of brass which can contribute to COAL variance.

 

12 minutes ago, MikieM said:

The ogive of the bullet I use has no relevance to anything because it doesn't change. My concern is the length of the bullet from case head to bullet tip. I have already found that my seating depth will not put the bullet into the rifling, so my only real concern is OAL from a pressure standpoint.

 

 

Because the seating stem contacts the ogive.  If there is variance in the bullet profile, the seating depth can vary (even though all the bullets may be identical in length).

Here is just one of many threads on this topic:
 

 

Edited by RDA

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Mixed brass vs one brand is one of the main contributors to variance in length from case head to ogive.  Also variance in the ogive diameter will have a bad effect on the cartridge overall length.  Full metal jackets and same brand of brass will normally lead to least variance in length overall or measured to a diameter on the ogive.

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39 minutes ago, Steve RA said:

Mixed brass vs one brand is one of the main contributors to variance in length from case head to ogive.  Also variance in the ogive diameter will have a bad effect on the cartridge overall length.  Full metal jackets and same brand of brass will normally lead to least variance in length overall or measured to a diameter on the ogive.

 

You're saying that when using mixed brass a reloader will see a variance in OAL?  We are talking about ammo use in semi-automatic pistols, right?

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