to little neck tension???

SS-8541-dono

SS-8541-dono

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Full Member
Minuteman
Jan 23, 2011
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missouri
#1
i have purchased a new forster neck bushing bump die and as per the instructions i ordered a bushing .002 smaller than the od of a fired case from my bolt gun , i resized the neck with the new bushing die and went through all my usual reloading steps and when it came to seating the bulet there is very little neck tension when it is seated.

my question is this, if the bullet once seated is being held into the case am i go to go even though i can move it in or out of the case by hand if i put slight effort into it?

my case neck od measured .341 before sizing and .339 after sizing but if i put some force to it i can move and spin the bullet in or out of the neck of the case?

i need to put some reounds down range this weekend and do not want to wait for another smaller bushing to come in am i good to go or is firing these rounds with this little amount of neck tension a bad idea?
 
#2
Re: to little neck tension???

If I could move a bullet by simply pushing and pulling on it I'd start over. If your fingers can do it what will recoil do? Just my opinion but these ain't 22LR's we're dealin' with.

I think you're to measure the O.D. OF A LOADED ROUND and deduct from that. At least that's how Reddings instructions read last time I checked. If Forster's instructions don't read that way than I stand corrected...but it sure as hell would explain your lack of tension.

Good luck.

ETA: Hmmm...bump die huh? I honestly don't have any experience with them.
Sorry.
 
#4
Re: to little neck tension???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FORSTER INSTRUCTIONS</div><div class="ubbcode-body">Bushing Selection Algorithm
[(case neck wall thickness x 2) + bullet diameter] – 0.002” =
correct bushing size (number on bushing)
OR
Micrometer or Dial Caliper: Measure the outside neck diameter of
several <span style="font-weight: bold"><span style="color: #FF0000">loaded cartridges</span></span>. Ideally, this measurement should not vary
more than 0.001”. Use the smallest diameter in the formula below:
cartridge case outside neck diameter – 0.002” =
correct bushing size (number on bushing)</div></div>

Full instructions HERE.

I wouldn't shoot 'em but that's me. I don't like unpredictable and I don't know with certainty what they'll do.
Tread with caution.
 
#5
Re: to little neck tension???

Won't "hurt" anything but your data will be skewed and group size will probably not be all that great.

I've seen guys soft seat bullets (start long, leave neck loose enough that when bullet hits lands it allows bullet to slide) but you are a bit loose for that from description I'm reading.

I wouldn't shoot them out of the magazine, single load only.
 
#6
Re: to little neck tension???

I don't use the forester neck die but I use a redding and only went .001 lower, per what Redding recommended. Anyhow I can try and push the bullet tip with great force into a wood block and I get no movement what so ever. You might be measuring wrong or using crappy brass in that the neck wall thicknesses are all inconsistent.
That is why I moved to all Lapua brass.
 
#7
Re: to little neck tension???

OP,

I was taught to run with as little neck tension as you possibly can without altering OAL due to recoil.

I determined this by loading up 3-4 rounds in varing neck tension from .001" to .004", mark them, load them in a magazine and go have yourself a range sesion. Put the magazine IN the rifle but single load for 20-30 rounds. Pull the ammo and see if any OAL's shrunk under recoil. Go with the least ammount of tension that will hold its OAL.

A heavy, light recoiling rifle can get away with .001" tension, but a light weight, heavy recoiling rifle might need .002" or more.
 
#9
Re: to little neck tension???

I thought when I seated the first bullets in my new lapua brass and it measured .339 OD thatd Id need a .336 bushing, not so, didnt have a lick of tension, had to go with a .334, and that worked out just fine. Yeah, I could seat the bullets with my fingers and pull them out, too.
 
#10
Re: to little neck tension???


To answer your questions about bushing size. Measure the OD of your loaded rounds. Bushing selection should be .001"-.002" smaller than the measured od of the neck. This still won't give you your "neck tension" per say.

You need to know how thick your brass is. For example: Let's assmue your loaded round measures .337" outside neck diameter.

Your brass neck wall thickness measures .013" avg for the 4 sides (neck thickness will vary with brand).

So .015 x 2= .030" of brass thickness accross the diameter of the neck.

your sized neck OD measures .339"

.339" - .030" = .309" Internal diameter of the neck.

If you go and seat a .308" bullet (and that's if the bullet diameter is even exactly .308" it will most likely fall through.

Long story short, easiest thing to do is measure a loaded round neck OD. Order bushings -.001", -.002", -.003" smaller than your loaded round from midway or sinclairs.

Try the -.001" and see if you have enough neck tension. If not go with the -.002" and see if that works better. Then return the -.001" bushing. I'd keep the -.003" to account for work hardening of the brass in the future unless you plan on annealing. Otherwise your can return that one too.

You don't need any more than -.001-.002" of neck tension. More than that and your just working the brass more than is necessary.

my .02
 
#11
Re: to little neck tension???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Frogman77</div><div class="ubbcode-body">
To answer your questions about bushing size. Measure the OD of your loaded rounds. Bushing selection should be .001"-.002" smaller than the measured od of the neck. This still won't give you your "neck tension" per say.

You need to know how thick your brass is. For example: Let's assmue your loaded round measures .337" outside neck diameter.

Your brass neck wall thickness measures .013" avg for the 4 sides (neck thickness will vary with brand).

So .015 x 2= .030" of brass thickness accross the diameter of the neck.

your sized neck OD measures .339"

.339" - .030" = .309" Internal diameter of the neck.

If you go and seat a .308" bullet (and that's if the bullet diameter is even exactly .308" it will most likely fall through.

Long story short, easiest thing to do is measure a loaded round neck OD. Order bushings -.001", -.002", -.003" smaller than your loaded round from midway or sinclairs.

Try the -.001" and see if you have enough neck tension. If not go with the -.002" and see if that works better. Then return the -.001" bushing. I'd keep the -.003" to account for work hardening of the brass in the future unless you plan on annealing. Otherwise your can return that one too.

You don't need any more than -.001-.002" of neck tension. More than that and your just working the brass more than is necessary.

my .02 </div></div>
I did that same exact thing, my loaded lapua brass measured .339 so I ordered a .336 bushing, that didnt work, had to go with a .334, perfect fit.
 
#12
Re: to little neck tension???

Jgorski,

How many firings on this brass? Do you know what the neck wall thickness is??

It's possible that the brass is work hardened, and even using the correct bushing you won't be able to size the neck enough. The only solutions are to either use a smaller bushing or anneal the brass.

What caliber are you loading? I'm assuming it's .30 caliber. .339" loaded neck diameter seems a bit large to me, even for lapua brass. Is that the fired case neck diameter???

 
#13
Re: to little neck tension???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Frogman77</div><div class="ubbcode-body">Jgorski,

How many firings on this brass? Do you know what the neck wall thickness is??

It's possible that the brass is work hardened, and even using the correct bushing you won't be able to size the neck enough. The only solutions are to either use a smaller bushing or anneal the brass.

What caliber are you loading? I'm assuming it's .30 caliber. .339" loaded neck diameter seems a bit large to me, even for lapua brass. Is that the fired case neck diameter???

</div></div>
The Lapua 308 brass is new, and I measured with bullet seated, some were measured at .338", I thought a .336 bushing would be perfect, after I sized the first fired case and tried to stick a bullet in the case it slid in with no problem, thats when I ordered the RCBS Tungston Disulfide bushings(.334 for lapua & .331 for Win brass) mainly since you really dont need to lube the necks with this coating. Midway did give me back the $18.99 since I did follow the directions per the instructions for that product.
 
#15
Re: to little neck tension???

It's been my experience that the newer the brass is, the more spring-back I get. When you sized your new necks at .002 under the target size, you probably got more spring-back than older brass would give you and thus a larger I.D. After a couple of firings, you might find that you can go back to the original sizing bushing.

It's too bad inside micrometers are so expensive (several hundred dollars from what I've found). Sinclair sells a tool where you expand a gizmo inside the neck and then use calipers to measure that. I've got one but have got mixed results.
 
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