6.5 Creedmoor - poor neck tension?

[vulrath]

Okay, so I sat down to do some loading for my 6.5 Creed monster (ARC Nucleus) last night and got super confused and frustrated. I'm not new to reloading, just to reloading for precision.

Equipment

- Lee Challenger press
- Redding FL Type S bushing die
- Hornady LNL 0.290" steel bushing
- L.E. Wilson chamber type seating die
- 1 ton Dayton Electric arbor press
- Imperial sizing wax
- Hornady One Shot spray lube

Components
- once-fired Starline brass
- Federal LR magnum primers
- IMR 4155 (test run of 41.7-42.2 grains; I think I hit a node at 41.8 and I wanted to confirm)
- Berger 6.5mm 140gr target hybrids (PN 26714)

Objective: 1000 yards, fed from a AI style magazine (I currently have PMAGs, but that could change). I might compete with this rifle eventually; right now I'm not a good enough driver.

Now, what I'm finding is that I can push the bullet with my finger tips after seating, and more importantly it seems that the action of stripping a round off the magazine and pushing it into the chamber is enough to drop the COAL by as much as 0.040". That's a huge amount; unacceptable, really.

I clean using dilute Hornady One Shot solution in an ultrasonic cleaner. Only thing I did differently this time compared to my 308Win loads was skipping my usual second dip in the US before I started loading. Is it possible the leftover lubricant is contributing significantly to my piss poor neck tension? Should I decap and wash everything again?

I also found that my neck tension on a loaded dummy round was almost 0.001" oversized, as measured by my Brown & Sharpe micrometer (based on what I saw I'd put it at 0.2906-0.2907"), even with the expander ball removed (which helped dramatically, actually). I'd expect some springback, but would going down a bushing size help?

I even went so far as to take a random bullet and check it with the mic (it was a little over at almost 0.265"). Is there something I'm missing? This is nothing like what I saw with the cases as-new.

 

[338 dude]

Definitely drop down one bushing size

 

[243winxb]

would going down a bushing size help?

I think yes.? Or 2 bushing sizes?

But first take a fired case. Size. Measure outside neck diameter before & after seating a bullet. After seating the bullet, has the neck expanded by .002"? This will give good neck tension.

 

[338 dude]

A bushing squeezes In on the neck therefore your spring back will spring outward so if your bushing is .002 smaller you will end up with .0015 interference fit

 

[338 dude]

In my final step to set neck tension I use a mandrel which is .002 smaller than bullet diameter because the mandrel pushes the neck out word spring back goes in word so I end up with 2 1/2 thousands tension and that works great for me

 

[B23]

What's the thickness of the necks on the brass you are using and is it consistent throughout you brass?

IMO, using an expander button on the decapping pin defeats the purpose of using a bushing die.

It sounds like you need to drop down a size or two in your bushing.

 

[vulrath]

IMO, using an expander button on the decapping pin defeats the purpose of using a bushing die.

I'm away from the bench; I'll measure wall thickness when I get back.

It hit me like a punch in the jaw (oh, no wait, that was my tooth) while I was trying to go to sleep last night that this might be the case, which is why further experimentation occurred without it. I use Lee and Lyman decapping dies before cases go to the US bath anyway, so it's not like I needed it to hold the decapping pin anyway.

I have Hornady 0.288 and 0.289 bushings on order, set to arrive Monday. Gonna see if I can bum a 0.289 from a buddy for an afternoon to test.

I did drop a few of the unprimed cases in the ultrasonic as a test. After a rinse and towel dry I can confidently say that tension is 80% better than it was, but still not good enough.

 

[Retired Grunt]

I use a .288 with a Hornady Match Grade Die for Full length and Seating and don't have problems, I have used virgin Hornady, Starline and now Peterson Brass.

 

[B23]

vulrath, if your Starline brass has neck thickness around 13 thou , 13 x 2 + 264 = 290 - 2 gives you a 288 bushing and if you figure .5 thou spring back = 1.5 thou neck tension using a .288 bushing.

 

[vulrath]

I'm not sure I 100% trust my numbers, but I'm getting readings of around 14 thou. 14*2+264=292-2=290. So the numbers support the .290 bushing, but my real world experiences are telling me that it's not enough. My 0.289 bushing is arriving tomorrow; I'll give it a try.

Unfortunately I kinda shot myself in the foot by blindly trusting numbers given to me by the guy that got me into this stuff, and sizing everything before realizing there's an issue.

338 dude, I'm curious about this mandrel method. Do you simply use a super small bushing, then open it back up with your mandrel? Would you do it again if you were to start over again?

 

[338 dude]

I'm not sure I 100% trust my numbers, but I'm getting readings of around 14 thou. 14*2+264=292-2=290. So the numbers support the .290 bushing, but my real world experiences are telling me that it's not enough. My 0.289 bushing is arriving tomorrow; I'll give it a try.

Unfortunately I kinda shot myself in the foot by blindly trusting numbers given to me by the guy that got me into this stuff, and sizing everything before realizing there's an issue.

338 dude, I'm curious about this mandrel method. Do you simply use a super small bushing, then open it back up with your mandrel? Would you do it again if you were to start over again?

Everything I do is to resize my brass as little as possible my mandrel is .002 under bullet diameter as explained earlier the benefits of a mandrel as it’s my final step it absolutely gives me the same size every time and then you coordinate your bushing to move the brass as little as possible also any imperfections in the neck of your brass are pushed to the outside where you have clearance in the chamber and it does not matter with a bushing any lumps bumps are pushed inward which create more friction on the bullet bullet

 

[vulrath]

An update on this: my 0.289 bushing came yesterday. That seems to have corrected the issue, at least in the couple of dummy rounds I had time to throw together. I had set aside some of the "problem children" from the last time specifically for this test and it's been a decent success so far. The 0.288 bushing still hasn't arrived yet, but if I have to I will try going lower.

My next question is "why did this happen?" Is there an inconsistency in wall thickness between lots? I have 2, maybe 3, lots (I bought 2 bags of 50, and a bag of 100) of brass.

 

[Bc'z]

Depending on number of firings, possibly you just need to anneal your brass.
It's good to have various bushings for caliber being loaded, its surprising how much a .001 increase/ decrease in tension can and will effect accuracy.

 

[B23]

With a bullet seated what does the outside neck diameter measure?

 

[vulrath]

An update on this: my 0.289 bushing came yesterday. That seems to have corrected the issue, at least in the couple of dummy rounds I had time to throw together. I had set aside some of the "problem children" from the last time specifically for this test and it's been a decent success so far. The 0.288 bushing still hasn't arrived yet, but if I have to I will try going lower.

My next question is "why did this happen?" Is there an inconsistency in wall thickness between lots? I have 2, maybe 3, lots (I bought 2 bags of 50, and a bag of 100).

Edit: all of the brass has just 1 firing, possibly save 1 or 2 pieces. 99 pieces were annealed on a friend's Bench Source annealer, 100 were used as is. I was seeing close to 0.291" seated, but the ones that were working are measuring 0.290". The ones that were giving me trouble were showing 0.294 before seating but 0.291 after. I don't think I'm measuring correctly. My mic is good quality and in spec, so it must be the wrong kind for the work or I'm using it wrong because of my wildly conflicting measurements.

 

[243winxb]

"why did this happen?"

Brass necks can thin as they are sized & expanded. Even happens to neck turned brass wnen running a light .001" neck tension.

When taking measurement with a micrometer, stay away fron the neck shoulder junction.

I use a RCBS dial Vernier caliper, instead of my mic.

 

[vulrath]

Duly noted. I tried with my Mitutoyo digital but I must have been measuring the wrong spot. I was seeing anywhere from 0.013-0.015". I think I was grabbing either the shoulder or the chamfer.

 

[B23]

Calipers really aren't the best for measuring neck thickness it's best to use a ball micrometer.

 

[243winxb]

Measure outside neck diameter before & after seating a bullet.

Calipers really aren't the best for measuring neck thickness it's best to use a ball micromete

Calipers work for measuring loaded rounds neck OD. Turning the round can show if there is a "large" variation in neck wall thickness. +/- .001"

 

[jaygorski]

Starline 6.5 Creed necks measure anywhere from .0135"-.0141", I use an RCBS Ti Nitride bushing and then I run them thru a 21st Century Black Nitride Expander Mandrel which seems to expand the neck .0005" from my before and after measurements, if you can push your bullets in with your fingers using a 290 bushing you might get a .288 & a 289 bushing, try one of those Ti Nitride bushings from RCBS, no lube required.