Neck tension and pressure velocity

[WEL]

Loading 350 rem mag. Lee dies giving about .001 neck tension which was not enough to keep bullets from pushing into case with very moderate pressure. Tried a Redding die now getting .005. .376 sized brass .381 loaded round. Bullets seated a little harder obviously but not radically so by feel. I did have one case that was .375 or .006 under and seating force was extreme. Pulled that round. Question is how much velocity pressure increase from .001 to .005 neck tension? Running a load with Ramshot Tac that is at the low end of Barnes data.

 

[David Christian]

Not your exact question, but anything more than .003 interference fit is not increasing your neck tension as the bullet is just serving as a mandrel while seating. Seating force will feel different, but the tension on the bullet will not be any greater.

 

[WEL]

Ok. I was just wondering how much difference since I had worked up a load at .001 with the lee dies. I reduced the powder charge 1/2 grain since 58 and 58 1/2 were what for what.

 

[rwj]

Question is how much velocity pressure increase from .001 to .005 neck tension?

A chrono will tell you...

 

[tom]

My experiences show not much different if at all for velocities, but it will tune differently....maybe better maybe worse.

Tom

 

[WEL]

A chrono will tell you...

Yeah, curious to see. Most all the stuff I reload with standard dies run bout .002.

 

[mikecr]

Does your Redding die partial length size? No more length than seated bullet bearing?

 

[243winxb]

A crimp may be same as more neck tension? From https://discover.dtic.mil/

 

[WEL]

Does your Redding die partial length size? No more length than seated bullet bearing?

I’m not sure I understand where your going with this. I set the die up to not bump the shoulder since the brass had been sized once in the lee dies and the shoulder bumped .002. I backed the die off so it would just size the neck and nit touch the shoulder.

 

[243winxb]

Some more internet stuff.

 

[Oso]

I have a 223AI that I have finally gotten around to doing load development. Initially (a year ago), I fired a bunch of factory .223 ammo to fire-form cases to the rifle's chamber. I went to resize these cases through my Redding 223AI Full Length Resizing S Bushing die. There was a lot more resizing of the body then I cared for, and I will send off die to have it honed to my chamber.

The Neck OD of the fired brass was 0.255", which was tight enough for me to hand press/push bullets into case with just enough tension to loosely hold bullet in place. Based on rough measurements, I believe there was .004"-.005" gap between case neck and bullet. The seating depth plus any irregularities/denting along the case mouth was sufficient to hold the bullet, barely. I decided to see what would happen so I loaded (1) 10 rounds of Non-resized cases and (2) 10 rounds of Full Length Resized cases with 0.247" neck bushing.

I assumed that proper neck tension would seal the gases behind the bullet helping propel it down the barrel more effectively/faster. Whereas, the inadequate seal of the non-resized brass most likely allowed some of the gas to escape out around the bullet causing less pressure pushing the bullet. The average velocity was only 25fps faster with the Resized Brass... I thought this would be greater difference.