Overall cartridge length

[Wildstreak]

Do you adjust your seating die for each individual round?

Let add some context. I’m currently using new Nosler brass for my 280 AI. They are typically +/- .001 or .002 in length. (I’m waiting on my Giraud case trimmer so I'm currently without a trimmer). I don’t remember my CBTO off the top of my head but for conversation sake let’s say .05 jump is 2.630 CBTO. I’m using Redding competition bushing dies.

I’ve found im not getting case to case consistency on my CBTO. If I get a round at my desired length and leave the seating die at its current depth the next round may come in significantly shorter. So I have to adjust my seating die between each round.

I know we have to consider that the bullets aren’t exact from bullet to bullet but they should be pretty close.

Does anyone else do this or Am I overthinking this?

 

[Lawnboi]

Absolutely not.

Everything has some degree of variation, how much is acceptable will be apparent on paper. But I would never adjust my die to problems caused by inconsistent components or prior processes.

That extra length dosnt mean anything. Your giraud is going to trim off the shoulder so do make sure your sizing consistently.

 

[sndmn11]

I wouldn't bother trimming that brass since it is new and your max variation is .002".

The case length has no bearing on the functionality of the seating die.

Your variation is coming from bullet manufacturing tolerance. I have found I get more variation in CBTO/COAL with high BC bullets; my guess is that it is due to their sleekness.

Load them up and go shoot.

 

[Tullis94]

I used to have similar issues. I found that properly anneal brass and running over a mandrel solved the problem. Basically inconstent neck tension was causing inconsistent seating depth.

 

[wapitibob]

I anneal after every firing and dial in every bullet I seat, backing off about 5 thou.
I try hold my trim tolerance to 2 thou but the end of the case is sitting in space. Your chamfer will dictate neck ID/bullet contact as well as neck OD/chamber wall contact and there is no way hand chamfering a case neck will be any closer than 2-3 thou.

 

[ID_Matt]

I am going to guess it has to do with inconsistent neck tension causing the variations in seating depth. How much variance are we talking about? 5 thou doesn't bug me... 20 thou definitely would.

 

[Harvey_NW]

Another thing that might help if you don't have it already is a VLD style seating stem that makes contact further down. After switching my variation with Bergers or Hornady in every cal is typically +/- .001", if any. I expand for neck tension.

 

[Pickettpuncher]

I check every round I load and get some variation. I rarely ever get more than .002 difference in my cbto. If I get one that is longer than I should get I’ll run it thru again but I’m not messing with my die. Not using fancy expensive dies.

 

[wind gypsy]

Agree that it's probably a combo of inconsistent neck tension and a seating die that may not work well with a particular bullet.

If it's just a few thou I wouldn't worry about it. Damn sure wouldn't address an issue caused by other things by adjusting the seating die for each round. Wouldn't be surprised if the neck tension variance caused more issue than the CBTO variance.

 

[longrange13]

Do you adjust your seating die for each individual round?

Let add some context. I’m currently using new Nosler brass for my 280 AI. They are typically +/- .001 or .002 in length. (I’m waiting on my Giraud case trimmer so I'm currently without a trimmer). I don’t remember my CBTO off the top of my head but for conversation sake let’s say .05 jump is 2.630 CBTO. I’m using Redding competition bushing dies.

I’ve found im not getting case to case consistency on my CBTO. If I get a round at my desired length and leave the seating die at its current depth the next round may come in significantly shorter. So I have to adjust my seating die between each round.

I know we have to consider that the bullets aren’t exact from bullet to bullet but they should be pretty close.

Does anyone else do this or Am I overthinking this?

Yeah I wouldn’t bother doing that. It could be any number of things. If you aren’t using a comparator when you measure you will find that most bullets have a slight variation in length.

Also don’t overlook cheap calipers. Most of them on the market are junk and have a few thousandths variance. Pick up a set of mitatoyo calipers and it will improve your measurements I guarantee it.

 

[Mike D Texas]

All of that went away when I started using an arbor press and Wilson in-line seater dies cut with my chamber reamer.

I find that on a traditional press it’s a combination of loose press tolerances, press flex overall tolerance stack in dies and inconsistent neck tension.

How much difference does it make at .002-.003? Not enough in a hunting rifle.


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[longrange13]

All of that went away when I started using an arbor press and Wilson in-line seater dies cut with my chamber reamer.

I find that on a traditional press it’s a combination of loose press tolerances, press flex overall tolerance stack in dies and inconsistent neck tension.

How much difference does it make at .002-.003? Not enough in a hunting rifle.


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This is spot on. To get the absolute best spend the money on upgraded premium equipment. Is it necessary for hunting though, definitely not.

 

[Vern400]

A couple of ideas here.

I have found for myself that a slow steady motion seating bullets gives the best result. I'm using a rock chucker and RCBS micrometer competition and seating die.

If I purposely seat bullets much faster, a few of them will go a few thousands of an inch deeper.

If I'm using a heavy compressed load my bullet seating depth varies more.

The best box of 100 ammunition I have ever loaded had overall links that varied by 0.004 inch.

I measure every single completed round. If I get a reading that is suddenly 0.005 different from all the other cartridge, which does happen, I'll put them in a different batch and label it accordingly with the variation. I opened a box of those plinkers" later to shoot it and found that four out of 20 case necks had split.

Your goal should be to use the most consistent procedures practical. When that doesn't yield the expected result, set that cartridge aside for another use. On occasion I will press a bullet in and it doesn't feel right. Too tight, too loose, just simply not like all the others. That cartridge is just became a plinker.

 

[JFK]

What does your process of seating bullets look like? Something worth trying is to seat the bullet, raise the arm a bit, spin cartridge 180, then seat again. I do this as it’s the way that I learned and it’s automatic. Might help with consistency. Might not. Worth trying though.

 

[TaperPin]

In general the seating die is contacting the bullet in an area much more consistent than the tip and you don’t move it. Some bullet designs are very consistent and others not so much. You could always measure the bullets to see if the variations are mostly bullet related or seating pressure related.

If you are really concerned and are looking for a better way to measure it, one of the comparator attachments for the calipers reads length closer to where the lands contact the bullet. Also, new brass has much more bullet seating resistance than fired brass with a little carbon, which doesn’t help.

I‘ve had a few bad seating stems with a really rough interior that would allow the bullet to slip a bit as the grooves dug into the bullet as it was seated, which would make things worse. Polishing that out was quite easy with some 600 grit sandpaper on the tip of a bullet spun with a drill.

In the end you have to look at group size. If groups are worse when shooting a combination of longest and shortest, than a group thats all the same length, it answers your question. My experience has been there’s no noticeable change.

 

[allstajacket]

To piggyback off of this question, I will ask another..
I had some differentiation when loading some .308 last night, with an objective OAL of 2.750".

After trying to get them as best as I could, and making some adjustments along the way, I decided to re-measure today using the Hornady Ogive comparator.

I got the following results: (inches)

2.148
2.148
2.153
2.149
2.154
2.146
2.151
2.146
2.148
2.153
2.140
2.150
2.151
2.151
2.149
2.151
2.140
2.155
2.153
2.148

The longest at 2.155" and the shortest at 2.140". Is a 15 thou difference significant?

 

[TaperPin]

To piggyback off of this question, I will ask another..
I had some differentiation when loading some .308 last night, with an objective OAL of 2.750".

After trying to get them as best as I could, and making some adjustments along the way, I decided to re-measure today using the Hornady Ogive comparator.

I got the following results: (inches)

2.148
2.148
2.153
2.149
2.154
2.146
2.151
2.146
2.148
2.153
2.140
2.150
2.151
2.151
2.149
2.151
2.140
2.155
2.153
2.148

The longest at 2.155" and the shortest at 2.140". Is a 15 thou difference significant?

.015” is a lot. By culling out the shortest and longest it reduces it to .006”, which is closer to normal, but every bullet manufacturer has different quality standards so there is no exact correct number. To see if this makes a difference with your gun, shooting a group with the cull cartridges should give you the answer.

I save the cull bullets for fouling shots or practice.

 

[allstajacket]

15 thou is a lot. Cull out the 2.140” and you‘re down to .007”, which is still not great.

.015” is a lot. By culling out the shortest and longest it reduces it to .006”, which is closer to normal, but every bullet manufacturer has different quality standards so there is no exact correct number. To see if this makes a difference with your gun, shooting a group with the cull cartridges should give you the answer.

I save the cull bullets for fouling shots or practice.

I ended up loading up a new batch, and once I got the overall length I started only using the cartridge base to ogive measurement. Ended up with a batch of 20 with a deviation of only 3-5 thousandths.

Might pull the previous batch. Only 20 rounds thankfully. I had another issue where the case mouth was a bit too tight, so I had a small amount of of the bullet jacket being sliced off when seating.

So I’ll pull those, toss the projectiles, and use a hand reamer to open the case mouth a touch to make it easier to seat.


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[TaperPin]

3-5 thou sounds much better.

When copper bullets first came out a lot of us had bullet shavings during seating even with a good normal chamfer - the VLD reamers have a longer chamfer and solved that problem - it also works nicely with all types of bullets.

 

[sdupontjr]

One thing to consider when measuring is what type of bullet are you using? It was mentioned that the 308 loads deviated by .015". I also agree that is alot. What I found when loading 155 lapus scenars in my 308 was that the tip of the bullet was bottoming out in the RCBS seating stem thus giving me a different measurement each time. Not .015", but on the line of .003"- .005". Once I found this out, I pulled the seating stem, drilled a small hole in the seating die and polished it. Now the tip of the bullet clears and the seating stem grabs further down the bullet to seat. Problem went away. Then I read about VLD type seating stems and my solution came up in a thread and folks had been doing this for some time. I have since ordered a custom seating stem for my 155's from RCBS and now if I load 20, I might have one that it .001" difference. Just a thought.