11-22-2023, 11:19 PM (This post was last modified: 11-23-2023, 12:38 AM by Klem.)
KW,
Why do you say that, I've just said it works?
Sized OD neck: 0.2860"
Seated OD neck: 0.2900-2905"
Neck tension: .004 - .0045"
SAAMI chambers are .300" ID. Neck stretch when releasing the bullet to sealing against the wall of the chamber will always be way more than any neck stretch holding the bullet from sizing. Total stretch from sized to spent is 0.014".
No splits in Lapua cases over 10+ firings.
If Scott is going to spin and file the stem then sure, he can stop along the way at lesser tensions and see if bullets still move. Less stretch equals more case life. He can only file the stem down to whatever the die is squeezing however. Removing the stem altogether and sizing a single case will reveal the max neck tension possible.
I used to run .004+ all the time with no issues in a bolt gun, back when I shooting a lot of compressed loads and didnt want the OAL/BTO growing over time before I could shoot it!
For me, when I've run .004" of tension, it feels too tight when I seat. OTOH, .001" is certainly not enough for me. Gas guns can be fairly violent when they cycle. Seems more are overgassed than not these days. All of our mileage varies.
For me, when I've run .004" of tension, it feels too tight when I seat. OTOH, .001" is certainly not enough for me. Gas guns can be fairly violent when they cycle. Seems more are overgassed than not these days. All of our mileage varies.
KW
KW,
As I said, .004-.0045 works, so with respect, 'feeling tight' is relegated by reality. Please don't be giving advice based on feelings.
As for more gas guns being overgassed nowadays - really? I get that you want to jump into the site's social banter, but blurting out anything just fogs up technical discussions.
11-24-2023, 12:29 AM (This post was last modified: 11-24-2023, 12:37 AM by Klem.)
scott>' Wrote:With the stem removed theres .006 of neck tension. Lee actually sells a pin with a .260 expander.
Scott,
That sounds perfect. You can either file down the existing stem until the bullets stop creeping, or buy the .260 expander and see if that works out of the box (should do). Let us know how you go.
As you know, not all .264 bullets are the same thickness. Here's a chart of popular bullets used in Grendel. Bullet thickness is not critical to solving your problem but might be when you get into fine tuning loads. The 'OD Sized' is obviously my gun but the trend is universal - that Nosler are slightly slimmer bullets, and Hornady are slightly thicker. Lapua brass is typically thick at the neck, 0.013"-0.0135".
scott>' Wrote:With the stem removed theres .006 of neck tension. Lee actually sells a pin with a .260 expander.
Scott,
That sounds perfect. You can either file down the existing stem until the bullets stop creeping, or buy the .260 expander and see if that works out of the box. Let us know how you go.
As you know, not all .264 bullets are the same thickness. Here's a chart of popular bullets used in Grendel. Bullet thickness is not critical to solving your problem but might be when you get into fine tuning loads. The OD is my die of course but the trends will be the same in yours. The takeaway here is that Nosler are slightly slimmer bullets and Hornady are slightly thicker.
scott>' Wrote:Thanks for all the replies. I was only getting .001 neck tension. Im going to have the expander ball turned down to increase the neck tension to .004. Also Im going to look into a better set of dies
Whidden makes an adjustable expander ball decapping stems. Their dies are expensive but you can use their decapping system in Redding dies. Point being, you can get a Redding FL Bushing die, using tapered bushings from either SAC or LE Wilson make runout a thing of the past. Then with the Whidden adjustable expander balls and tapered bushings, you've got total control of neck tension with any brand of brass and neck thickness.
scott>' Wrote:Thanks for all the replies. I was only getting .001 neck tension. Im going to have the expander ball turned down to increase the neck tension to .004. Also Im going to look into a better set of dies
Whidden makes an adjustable expander ball decapping stems. Their dies are expensive but you can use their decapping system in Redding dies. Point being, you can get a Redding FL Bushing die, using tapered bushings from either SAC or LE Wilson make runout a thing of the past. Then with the Whidden adjustable expander balls and tapered bushings, you've got total control of neck tension with any brand of brass and neck thickness.
At .004 tension my bullets still shoot forward, made a dummy round to make sure it wasnt the powder charge acting like a deadblow hammer, no difference. Lee crimp die makes no difference either, can ruin the bullet before the movement stops. Maybe .005 tension?
Federal american eagle 90gr tnt factory loads move forwards as well. No wonder they pull so easily.
I expect alot if not most people are having this issue without even knowing it. Pretty maddening, all the wasted components trying to figure out loads when COAL is all over the map. I should have checked this long ago apparently.
BluteEhre Wrote:At .004 mine still move.. maybe .005 is the ticket. Crimp die ruins bullets before solving anyrhing in my case.
Blute,
Maybe, although it could also be a lack of elasticity (ductility) in the brass. If the neck is not elastic enough then it doesn't matter how narrow the neck is for seating. Bullets will expand the neck as they are seated but will be held with less friction than needed to stop it moving. Annealing should restore much of the original elasticity. If not, case-hardened brass that has been fired multiple times will hold the bullet less than needed, regardless of the neck diameter.
Obviously the amount of shank in contact is also important, as is the weight of bullet (inertia).
I have wondered about the brass in general. The brass i notice this with is only 2 or 3 times fired Hornady brass, so i am a bit disappointed as a non annealer to think it may be my issue. I agree some bullets and seating depth play a roll. I notice it the worse with my 90gr tnt loads that arent seated all the way into the neck, however even the factory american eagle loads with this bullet jump forward when chambering.
I think everyone should try this test, as i mentioned i expect its a wide spread issue and likely why loading this cartridge to max accuracy can seem like we move one step forward and two back at times.
I plan to anneal with a blow torch as per (Dan Newberry) https://m.youtube.com/watch?v=qlIjQ05aKzk
some rounds and try the same test in a couple days.. will report if my findings.
BluteEhre Wrote:I plan to anneal with a blow torch as per (Dan Newberry) https://m.youtube.com/watch?v=qlIjQ05aKzk
some rounds and try the same test in a couple days.. will report if my findings.
The torch method works great but the smaller cases might get too hot to do by hand. Many chuck them up in a handdrill with a socket, I use a Lee case trimmer stud and shell holder. The handdrill rotation is more consistent exposure to the flame too.
Annealed maybe helped a little, but still jumps, tried brand new hornady brass, no difference it jumps. Basically the action is acting as a kenetic bullet puller, use charging handle and they dont move or at least not the first couple chamberings, release the bolt lock and chamber and they do. Guess it may be most important to find a load that isnt very coal sensitive as far as accuracy goes. Tried a few different factory loads and they all jump .002-.005 out.
.002 is not a lot of jump in a system that is, as you say, a kinetic bullet puller. Maybe the cavity bullets are more slippery or softer than other brands (I've never used them). Maybe that's as good as it gets without going nuclear and doing weird things like gluing with nail varnish, which we see in military ammo sometimes. Or insisting all bullets have a cannelure into which the case mouth is roll crimped (again, some military ammo).
What you could do now is hand feed individual rounds gently into battery and fire for group size. Then get a similar number of rounds but let the action hammer the rounds in semi-auto mode as normal. If there is no noticeable difference in group size then you could accept it as a non issue.
I experienced similar frustration at the start of using this calibre. Bullet creep from Inertia was so bad that some bullets were flying forward and jamming into the lands before firing. Meanwhile others were jumping forward a little bit but not touching the lands. This creates a vertical string on the target which I thought was shooting skill. Took a while to figure out and now grip bullets with the strength of a thousand guinea pigs.
