.001 neck tension for .308 F-TR load?

[calgarycanada]

Member of Canadian national team once told me he runs 5 thou neck tension, when I asked him how he keeps his vertical so small.

 

[Toejoe12]

A great benefit in the shooting sports gaining popularity in the last decade is the onset of better/different equipment and technology. This in my opinion has brought more great minds into our sport, many are on this site. It has opened the door to new ideas, old ideas with different twists, and old ideas with better equipment (again my opinion). I am a tester and enjoy doing it almost as much as competing. As many veterans of this site often advise........go out and test. I do! I'm fortunate to be close to a 500 yd range and frequent often as well as several close friends that share my passion. We share openly "information" as we are a team.

One of the areas we've spent significant time testing is brass prep and the MANY variables involved that lead to consistency in each loaded round. My/our experience is consistent neck tension is paramount to precision accuracy and will definitely become more and more obvious as you move back in distance. At 1000 yds it is an absolute must if you want to be competitive where precision counts.

The newer versions of arbor presses with pressure measurements combined with custom fit dies made measuring neck tension, friction, force fit..... etc using bushings (a tried and trued proven method so I'm not putting it down), some what out dated to the tools we now have easily available (again opinion). I have not used bushings in the last 1.5 years. My preferred method is running a certain size mandrel through the neck last. This does many things but the 2 most important I feel is controls "precisely" the neck size as well as ensures the "inside" of the neck is perfectly concentric. I had a mandrel die made that holds a collet, that holds a pin. Got the info and die maker info off this site. The pins I use are Vermont pin gauge easily purchased in the size(s) needed from Amazon for $7 each. If you're extremely anal you can pay $20 and order direct from VT Gauge and get a certified pin with in 1/10000 of an inch. Amazon offers in .0005 increments or if you want even more choices from Amazon, 7.80mm = .3071 and 7.81mm = .3074. After countless testing of different scenarios processes and even the order of steps within the different processes (there could be a book written on this alone) my/our current process is a variation of the below.

• Nk turn brass to desired nk wall thickness
• Clean brass or wipe down, whatever you prefer. Haven't found this much matters as nk tension can be controlled by mandrel size
• Anneal after every firing.......easy as I have an annealer
• F/L size (no bushing)...I had a die made to my chamber specs that size the neck down .0025 from fired case neck size
• Open neck back up minimally with correct size mandrel pin referenced above.
• Tumble in corn cob for 30 min to get whatever brand lube you use off case
• Trim or chamfer to my preferred specs if needed
• Prime and drop powder
• Seat bullet with another custom seating die I had a good friend make from the chamber of one of my shot out barrels....no better fit than that
• Use arbor press with psi measurement to seat. (I prefer between 30 psi and 50psi tension/fit) *

*Note: 30 to 50 is an over all range of comfort I have on the measurement. The lots of match brass I load will all be within 2 to 4 psi range of one another. Example: a complete match set....22 rounds including sighters will be 30 psi to 34 psi. Another match set of 22 could be 44 to 48 for all 22. Doesn't matter to me as long as they all are within my tolerances for the 22 set and fall with in what I deemed the sweet spot listed on the last bullet point above.
I have my brass in lots of 75 for a full match and 90% of the lots fall in the 35 to 40 psi range. I have no idea what that translates into inch measurement fit/tension. It's just a different process and measurement I feel is more precise.

A version of the above process has been very successful the last year and a half for the core guys I shoot with constantly.

Sorry for the long response but I'm on vacation and a bit bored and thought I would give a different perspective.

 

[Alex Wheeler]

Heres a few targets I shot while tuning up a 7saum hunting rifle #4 contour barrel. I shot these all at 1k in the middle of the day. Not the best groups in the world but OK for a hunting rifle. No turn brass with .005" neck tension. I would expect much better in a target rifle, but Ive never been able to shoot a hunting rifle much better than 3-4" at 1k.

 

[dcali]

Drew just needs enough room to get the boat tail started. Then fully seats with a wilson die and 3lb hammer.

I might try seating some 7mm bullets in some 6.5-284 brass. Necking up is for suckers.

 

[cw308]

Toejoe12
Thank you , great read . Sharing information to help each other is what this forum is about . Last year at the range a few benches down from mine ,this guy was shooting reloads in 308 , to make conversation at a cease fire time , l said your reloading 308 he said yes . I asked what powder , charge an bullet are you shooting . He said , I'm not telling you my information , you wouldn't tell me yours . He cought me so off guard I just said ,WHAT . I guess in not such a nice way . Then said I have no secret load and just walked away . He's the only one in this shooting sports that wouldn't share information . Thanks for responding TJ12

 

[skiutah02]

I test religiously, and am always happy to share what I have learned. I keep no secrets. When newish shooters set or tie national records after helping them out (this has already happened) I feel like part of the team, and when they stomp me the next time we meet (which has also happened) it takes a little of the sting out of the drubbing.

 

[dcali]

The idea that there are any secrets is sort of amusing. It's really a matter of discovering the whys, which then lead you to the whats. There is no secret recipe - only the understanding and process that lead you to good results.

 

[Alex Wheeler]

What I can say about most shooter's "secrets" is that all they are, are things that most people wouldnt think to try that ended up working really well.

 

[cw308]

In 99.9% of the time everyone in the shooting spot are willing to share , I just bumped into that 1%er.I was taken back for a second though . Only a second . Sorry for changing the subject of the post .

 

[270WinDude]

Neck tension is a weird area of reloading where people like to come up with theories on what should work and why, then stick with it. While in other areas like powder charge, we all just test it until you find the right place. I recommend treating neck tension the same way.

From all I've gathered it depends on the cartridge. The Litz related testing I've read he tested for velocity spread and what was interesting to me was that in the 308win and 223 he didn't record any differences yet in the 243 he did. So until someone produces a cartridge specific test for the particular one I am shooting I'll continue to operate under the assumption that I have to test all these variables. The best group I've shot so far was some rounds I should have pulled because the bullet was so loose I could pull it out with my hand if I needed to and a more jump then normal. Having said that, I do realize how hard that would be to make that into a consistent thing, so I do what's repeatable.

 

[270WinDude]

I might try seating some 7mm bullets in some 6.5-284 brass. Necking up is for suckers.

ah yes the good ole 284-6.5-284win jam right?

 

[Richard Coody]

Is the force needed to push the bullet out of the case neck the same 5 days (weeks?) after seating the bullet as it is after 5 minutes?

If not, what's the difference?

i have no idea but my experience with my benchrest rifle has told me it likes freshly loaded ammo. just my experience that i get high 2's with week old ammo and 1's and low 2's loaded the night before. I know others have different experiences. whatever works for you.

 

[cw308]

Could it be bonding of the neck an bullet ? That's why I started using dry neck lube to the bullet . It working out well so far for me .

 

[Richard Coody]

Could it be bonding of the neck an bullet ? That's why I started using dry neck lube to the bullet . It working out well so far for me .

i leave the carbon in the necks undisturbed except for a light brushing before charging. use the imperial dry neck lube on new brass.

i use the 21st century shooting hydro press and have found if i size several days before seating bullets seating effort goes up a lot. something is happening with the brass during that period of time. now i use an expander mandrel sized for .001 neck tension right before charging and seating. works very well for seating effort consistency.

 

[Bart B.]

Could it be bonding of the neck an bullet ? That's why I started using dry neck lube to the bullet . It working out well so far for me .

If you're referring to dissimilar metal bonding by electrolysis, that is possible. Especially if both bullet and case surfaces are very clean.

Some years ago at a match, someone used very old reloads 'cause he "wanted to use them up." One round was so much over pressure it froze the bolt as the rifle recoiled much more than normal. Finally was able to open the bolt then extract the 30-06 case. Its neck was torn off at the shoulder and went downrange with the bullet.

This is one reason military ammo has that sealant between bullet and case neck. Bullet release force stays more consistent a long time.

 

[riflewoman]

For a “50,000 foot” background:

https://en.m.wikipedia.org/wiki/Cold_welding

 

[Dusty Stevens]

I know last weekend i pulled some bullets that had been loaded over a perfect carbon layer you guys like for 2 yrs and i had to seat them deeper to break the seal and it pegged my hydraulic press out to the max and they broke loose with a loud pop. When they were seated they had around 15psi

 

[Bart B.]

Some people on military teams used a Lyman 310 tong tool seating 7.62 NATO M118 match ammo bullets .010" deeper breaking that sealant to cut velocity spread and vertical shot stringing at long range in half. Bullet extraction force spec was 20 pounds minimum. Some lots had a 5 to 10 pound spread about a 25 to 30 pound average.

 

[Drop Port]

I know last weekend i pulled some bullets that had been loaded over a perfect carbon layer you guys like for 2 yrs and i had to seat them deeper to break the seal and it pegged my hydraulic press out to the max and they broke loose with a loud pop. When they were seated they had around 15psi

In the past when i had more time, got out more and was more neurotic, if I loaded in advance for a match or anticipating a day of shooting, I seated a bullet half stroke and quickly ran them through the seater the day of or night before shooting.

 

[cw308]

Bart B
Knowing bullet extraction point is far above my pay grade . I can't imagine the amount of gages an tools you all have to test . Just to make that one hole five shot group . Easier to carry a dull #2 pencil , think of how much powder an bullets you could save making your target looking good .

Chris