Seating depth headache

Hey guys, I’m hoping for a bit of advice.
While seating projectiles in my .270 I’m getting inconsistencies with the seating depth. It’s about 5thou difference from one round to another, is this significant enough to try and fix? I’m using a Lee seating die with a Lee press. I try to always use the same pressure when fully raising the ram. I have also taken out and cleaned the seating plug and shell holder.
Could this be an issue with neck tension differences between cases? They all go through the same full length resizing process.
I’ve been reloading for a couple years so I’m constantly realising how much I still have to learn! Any ideas/advice welcome.
Cheers,
Louis

Try annealing your brass. Can have a bit of pressure seating this case. MY 2C.

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Originally Posted by TeRei

Try annealing your brass. Can have a bit of pressure seating this case. MY 2C.

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Definitely agree with annealing
+
Have you trimmed your cases ?
The other issue I've had with Lee presses is them having play between the quick change insert and the press, allowing the die to move.

Yep brass is always trimmed. I do have access to an annealer so I’ll have a play with that. Cheers!

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Originally Posted by KimberHunting

Yep brass is always trimmed. I do have access to an annealer so I’ll have a play with that. Cheers!

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Don't underestimate the quick change bushing play, caused me no end of headaches when I first started.

How are you measuring them,, if your using calipers measuring from base of case to bullet tip, possibly could be inconsistencies in the bullet length....

https://www.brownells.com/reloading/...prod83792.aspx

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Originally Posted by matagouri

How are you measuring them,, if your using calipers measuring from base of case to bullet tip, possibly could be inconsistencies in the bullet length....

https://www.brownells.com/reloading/...prod83792.aspx

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Very valid point :thumbsup: Hornandy comparitor set is just as useful and probably a little easier to find in NZ

Another thing to check is the bullet length base to ogive they can vary .001" to .005" and the seating stem pushes on the ogive not the tip
If you are that fussy about accuracy why use Lee products they are interior to every other brand on the market the only reloading tools I have had
issues with are Lee.

and I on other hand really rate LEE tools and use them in preference of other brands when I can.....
indeed how are you measuring??? tip to base with sierra HPs HAS ALWAYS HAD LARGE VARIATION.... does your target paper notice the difference??? is it less than 1mm ?
take 3 closest rounds and fire group..then the shortest,the longest and one in middle and fire group....any real world difference in group size??? if the mixed up lengths group is still OK... stop fussing and enjoy life.....

I had the same thing with a Lee press and the quick change bushings (which I never use or intend to use).
I've replaced the press with a RCBS Rock Chucker Supreme and a couple nights ago loaded some 6x45mm. My calipers measured 25 rounds to be within 0.0005" of each other ogive to cartridge base. I don't actually trust my calipers to measure variations of 0.0005" but I was happy with my first projectile seating with the RCBS press as clearly they were consistent beyond my ability to measure variation.

The quick change bushings to me seem like a solution looking for a problem. They introduce slop and don't seem to be any faster than screwing the dies in normally.

If I was you I'd put some thread locker on the quick change bushing and effectively delete it from the system.

Also concur with above posters if you are measuring to the bullet tip you will be picking up variations not related to your seating depth.

Agree with above about measuring to ogive rather than bullet tip.
If you are measuring to the tip, try measuring unloaded projectiles, you might find your 5thou of error there.

How is accuracy?
If accuracy is good enough for your use then don't sweat it.

I measure base to ogive so I’m thinking it’s press/die related rather than projectile inconsistency. 145eldx for reference. The Lee seating stem not suited to a vld projectile maybe?
That’s good feedback on the quick change bushing, I’ll find a way to lock that up tight. Accuracy is ok for my use, average around .7moa which is fine for the ranges I’m shooting. I guess it just bugs me that there is something not consistent and I can’t fix it!

I also agree with the Ogive stuff. I was seating some Hornady 150 gn round nose recently. Granted I didn’t have the perfect seating stem for this projectile but through factory variations in the tip shape, I was getting enough seating depth variation that I was able to visually detect it as the rounds came out of the press.
They still shot to the same POI but it wasn’t tested at .270 distances.

However my comments are not to rule out that chances are that the causes are actually a little bit of everything. Think of when you get a 1” group instead of a 0.5” group. You can’t accurately say it was 100% one thing and not another. It’s more that if we could break it down into the various blame factors it would look something like:

Shooter 25%
Breeze 23%
Barrel harmonics 12%
Barrel fouling 16%
Parallax 9%
Chamber slightly off centre to bore 3%
Other factors 13%


Your seating depth situation may likely be a combination of several factors.
Sometimes they may combine to create the outliers of 5thou variation. Sometimes some may cancel others out and that’s where you get your one thou variations.

Annealing brass does help. Happy to do for you.

Completely agree with annealing.
I also recommend neck turning and bushing dies to give consistent neck tension. I turn all my necks on new brass, but just a light skim to even them up - typically about 1 thou. I only do it once then leave it alone. Even with Lapua there is around 1 thou neck thickness difference. Not for everyone, and tools cost a bit, but worth it in my opinion.

Anyway, try anneLing and if it’s good enough get on with shooting.

Are you using a powder charge that is crushing your powder??

Im doing so in my 223 - ok, different calibre, though IM also seeing variances in seating depth and thats using a micrometer seating depth addon - i will keep that odd ones aside then adjust my seating depth - however many thou -as needed to get the end result that it sits where I need it to be for the node... PITA at times!

Compressed loads can cause seating depth inconsistency as well, gave me headaches when I started loading for my rem mag.

Does the seating stem match the projectiles? Unannealed brass, different neck tensions and projectiles slip in stem. Will normally see a ring on projectiles tho

Cheers for the input guys. I annealed a bunch of brass over the weekend and have seen a massive difference, they even feel more consistent as the projectile is seating. Length variance down to about 2thou. I can live with that. Still haven’t secured the quick change bushing so that’s next.
For those asking, it is technically a compressed load but only ever so slightly.

I am currently using a Lee seating die and manage to achieve about a 2 thou tolerance. I absolutely agree that varying neck tension gives varying seating depths. New brass or annealing your existing cases will help. Having said that, 5 thou is far from the end of the world for most applications.

Another thing I found if not annealing every time was to brush the necks with a nylon brush after sizing. Seems to reduce inconsistencies in seating pressure you can feel when seating the projectile. Worked for me anyway.