Mandrel sizing for consistent neck tension

[highdrum]

I personally felt that lubing inside of neck prior to mandrel gave more spring back, resulting in more neck tension, that's why I use the expander mandrel w/o lube. This was observed on lapua 300norma imp cases that were salt bath anneal, dipped for 8 seconds @ 550° C.

 

[del2les]

Mandrel sizing in my BR rifles for decades with stainless mandrel with everything from .0005" to .002" neck tension depending on which grouped the best in each. Dry lubed inside necks with mica and nylon brush and no lube depending on group results. Most game hunting rounds I use a .001-.002" neck tension to prevent bullet creep under recoil.

 

[Mikecr]

Neck tension would be another thread.
But lubing necks does not change their spring back or tension. All it changes are seating/expansion forces.

 

[parshal]

I found a .0005" undersized mandrel with mica to work best in my 65SS. I had to make the mandrel. I'm going to grab some of those Sinclair mandrel .001 under for my others.

 

[BrentM]

Sinclair mandrel which is usually .002 under bullet OD. I turn necks, I bushing size .003 under, and mandrel expand back that .001. For lube I use 1 shot and spray a tiny amount at the neck mouth while spraying the outside for the bushing process.

 

[clownbuster]

Have been working on a load for a new 6.5 PRC and settled on a pretty good load with RL26 that's pretty consistent .5 to .7 MOA... In the process I had some test rounds that were a little hot so pulled the bullets with an impact hammer and charged them with my final load and reseated the bullets... Now I usually use these as fouler thinking that the neck tension won't match the rest of my brass... This time I had enough that I thought what the heck I'll see if they group with the rest of the fl sized once fired brass... So the .098 MOA group that resulted has my attention.... I'm thinking there might be something to Mandrel sizing....

So a few questions for those that have experience with mandrel sizing the ID
1) who's mandrels do you use (stainless or TiN coated)? 21st Century TiNi Turning Arbor
2) Do you inside lube before? No
3) Do you used the expander Mandrel? Or Turning? Turning
4) what relative size Bushing do you use? Play with bushings 3 to 4 tho under to get desired seating pressure.
5) Any other keys to success? Anneal after every firing, but make sure you do it before any case prep as annealing "alters" the shape of brass.

Thanks in advance for your help

See my responses in bold.
I will play around with bushings for neck tension depending on caliber/recoil. Light recoil gets light tension; heavier recoiling calibers get more.

 

[Frank Kalisz]

I use a custom honed Forster FL Die (without expander spindle) to get my necks 3 thou under bullet size, and then use a 21st Century TiN Mandrel Die to put neck tension at 1.5 thou. I use Imperial Dry Lube for the mandrel, and I also anneal with 550 degC salt bath. I have very little runout and everything seems consistent so far. I'm about to take my third batch to the range using this method, but I already see a huge improvement from my old body die and neck collet die.

 

[highdrum]

Sinclair mandrel which is usually .002 under bullet OD. I turn necks, I bushing size .003 under, and mandrel expand back that .001. For lube I use 1 shot and spray a tiny amount at the neck mouth while spraying the outside for the bushing process.

I have found my Sinclair seating mandrel to be 1 thou under, and the turning mandrel to be 2 thou under. I have em in 308, 7mm, and 6.5. My 21st century are for 257 cal.

 

[SealT5]

When available for my caliber I use Redding FL dies which usually size 4-5 thou under bullet diameter. Then use Sinclair SS expanders for final sizing. Works great and saves $$$ on bushings and bushing dies

joe S.

 

[338 dude]

Mike,
Why WS2 over HBN?

Or moly?

 

[338 dude]

Sinclair mandrel which is usually .002 under bullet OD. I turn necks, I bushing size .003 under, and mandrel expand back that .001. For lube I use 1 shot and spray a tiny amount at the neck mouth while spraying the outside for the bushing process.

Pretty much exactly what I do

 

[65WSM]

I too have found about 1.5 Thousandths under bullet size provides the neck tension that is the best compromise in variety of 6.5, .270 and 7mm applications.

I have found that polishing the inside of case necks with steel wool wrapped around a cleaning brush and motorized in a drill helpful as well.
The K&M mandrels are helpful in achieving the 1.5 thousandths inside diameter after sizing with bushing dies.
I also coat all bullets with HBN. No naked bullets. The first shot from a clean barrel will shoot into the group of following shots. I hunt with a clean barrel. Barrels last longer.

 

[misterc01]

I check the case neck at four points around it, and if they measure the same. I move on. If different, I turn the necks to remove high spots. I then resize them using a bushing to get .003 neck tension. The last step is run them through a Hornady concentricity gauge to get them to .002 or less and call it done.

 

[IHFarmer07]

I'm fairly new to reloading about a year into reloading and after a month or so of bad ammo that I made I did a bunch of research and bought a lot of tools/items for getting my one rifle I reload for for now to shoot good with low es/sd. So I bought a Sinclair mandrel die, expanding mandrel and turning mandrel, I used this method a lot and thought the runout that I had was basically as good as I could get so I kept using that method. Here recently I decided to try to get more performance and accuracy out of it so I started using better brass and neck turned some to test vs not neck turned. I actually have less runout with the forester fl die without the decapping/sizing stem, necks turned and NOT using the mandrel.....not sure if my mandrel is bad or what, I use imperial dry lube even. Bought the mandrels from PM tool.