Neck tension with slow powder

[rafale]

What's your experience about neck tension with slow powder like N 165.I know that the N133 need
more tension for 6PPC or 30x44(.002) but in theory for slow powder it will be bigger?

Thanks in advance for your views,

Michel

 

[MagnumManiac]

I have never seen a difference due to powder type used.
Most of my comp barrels (no mag loading) use .0015” or less. One barrel I have doesn’t like anything less than .004”.
Hunting rifles for me run .002”-.003” and powder type makes no difference.
Seating depth makes quite a difference of in accuracy for me though.

Cheers.

 

[mikecr]

What length of sizing do you reach your tension with (with resp to seated bullet bearing)?

 

[243winxb]

N165 is a very slow burn rate powder on the chart.

I would NOT want- light neck tension.
Standard primers.
A lot of bullet jump to the rifling.
Little bullet shank in contact with the case neck.

A small cartridge may no accept enough powder to get good velocity. Example IMR4831 in a 223 Rem.

https://thefiringline.com/forums/showthread.php?p=4928827#post4928827

 

[retired]

yes it is not as simple as just " A NUMBER".
cartridge bullet bbl length accuracy desired

 

[rafale]

Thanks for your views! The barrel is a Broughton 243 ,32" and I use a little jump .004 with a 105 grs scenar L.My actual neck
tension is .002 and the accuracy is a 1/4 at 300 m under good condition.I just curious what others shooters discovered with
very slow powder.

Michel

 

[243winxb]

I see no problem with .002" neck tension, N165, and the heavy 105 gr bullets. Your accuracy is great.

Using a 55 to 70 gr may be a problem with slow powder. IMR4350 with 70 gr Berger doesnt expand the necks on firing till i hit the maximum powder charge. Using a 10-1 twist barrel. Accuracy is good, its possible to get 5 shot groups at 300 yds just under 1" But not all the time.

I use IMR 4831 with a 90 gr Berger match. Best groups just under 1" @ 300 also.

Very old Rem 40 xb as it came from the factory in 1976. Very long jump to the rifling as the throat is shot out . It shot better many years ago. In 2000 when i saw benchrest groups posted online, i had to buy a Leopold 36x and bushing die to see what the old rifle could do.

 

[fguffey]

Thanks for your views! The barrel is a Broughton 243 ,32" and I use a little jump .004 with a 105 grs scenar L.My actual neck
tension is .002 and the accuracy is a 1/4 at 300 m under good condition.I just curious what others shooters discovered with
very slow powder.

I am not someone that can or will talk it to death; my cases do not have neck tension because I am the one that does not have a gage that measures tension. I use all the bullet hold I can get especially with slow burning powder. I know, it makes no sense to other reloaders but time is a factor. I do not want my bullets jumping out of the case before the powder burn gets serious. And then there is the beginning of the rifling, when my bullets hit the rifling I want the bullet past the rifling before it knows the rifling is there.

F. Guffey

 

[dmoran]

my cases do not have neck tension
I use all the bullet hold I can get

 

[243winxb]

Just for Mr. Guffey.

 

[Bart B.]

Good info, but the numbers are probably in pounds of force. Not per square inch.

That test is the best way to compare clearance or interference fit.

 

[Milo 2.0]

I do not know if it is because I seem to shoot the same cases or design of cases from year to year or what, but I have not measured neck tension with a caliper in 5 yrs. I go off feel and really need to buy that press setup from 21st Century, don't think it uses reg dies though.
I've brought more loads in adjusting neck tension in the last couple years than any other tweaking, it's easy to find a charge that holds vertical, sometimes seat depth alone can't tighten the group up. Adding some neck tension usually works here. With both slower and medium burn rate powders. I'm talking fired brass here, as with some new brass, you may need to expand it and reset tension to get it to work.
I can measure a couple, but I'm sure I'm at .004" measured neck tension on my XC's with Norma brass. VV N550 and RL 16 powders.

 

[243winxb]

Good info, but the numbers are probably in pounds of force. Not per square inch.

That test is the best way to compare clearance or interference fit.

I think he use a automotive tool that measures valve spring pressure In PSI ? If i remember correctly?

 

[Bart B.]

I think he use a automotive tool that measures valve spring pressure In PSI ? If i remember correctly?

Valve spring pressure measuring tools use pounds, such as 1 to 700 pounds like this one:

http://www.jegs.com/i/Proform/778/66775/10002/-1

You can calculate the pressure in the case to get the psi levels needed push a bullet out knowing the force needed to pull It out. Reciprocal of bullet cross section area in square inches times pull force needed. For 30 caliber bullets needing a 20 pound pull force, 1/.0745 = 13.4, 13.4 times 20 = 268 psi in the case.

 

[dmoran]

Both seating force and pulled force are easily influenced by neck preparations (friction). Dependent on the surface finish of the internal case necks, but .004" neck tension can seat and pull easier then .002" if the necks were prepped to have less friction. Friction being the biggest influence to the amounts of both seating and pull forces that will be needed, or so has been my experience.

 

[rafale]

I think that a neck tension of .004 is maybe to much for a single shot rifle .I use those amont of tension when I shot prone with a
military repeater rifle.

Michel

 

[Bart B.]

Friction being the biggest influence to the amounts of both seating and pull forces that will be needed....

Lake City arsenal case mouths have a .001" or more clearance fit to bullets. That's where where the liquid black sealant goes that when dry, bullet pull forces for 7.62 M118LR ammo has at least 20 pounds pull force needed. More friction in a sense as that asphaltum glue grips bullets.

M80 ball ammo starts out much the same then its case mouths are crimped into bullet cannelures. Which raises bullet pull force to at least 60 pounds to meet specs.

 

[dmoran]

I think that a neck tension of .004 is maybe to much for a single shot rifle .I use those amont of tension when I shot prone with a military repeater rifle.

I know several LR-Benchrest shooters who use up to .004" (some even more) neck tension. Both in smaller calibers as well as larger calibers. I believe .003 to .005" is very popular in 300-WSM for an example, and know a couple top competitors that use 6BRA/6Dasher that use +.0035" neck tension.

Neck tension is a key aspect to fine tuning a load, IME, that often is taken for granted or not tested.
Consistent neck tension / seating force is the key !.!.!

 

[Milo 2.0]

I think that a neck tension of .004 is maybe to much for a single shot rifle .I use those amont of tension when I shot prone with a
military repeater rifle.

Michel

Sorry, but you asked the question, and a couple guys stated .004" may be needed. Just try more tension, way better to run your own tests than to ask anyway.

 

[Milo 2.0]

Consistent neck tension / seating force is the key !.!.!

I like your way of thinking, I end up teaching a lot of guys to reload, and trying to get them away from the caliper way of measuring tension is hard. It's by the feel of seating bullets.