Runout Issues With 338 Lapua and Redding Comp Neck Die- Please Help!

[RAGGED]

Hello all, I’m hoping someone here can help me with an issue I’m having with my new rig, or at least explain in technical terms what may be happening. I recently picked up a SAKO TRG in 338 LM and have begun loading for it. I’m finding that my fired brass with runout of less than .001” is coming out of the neck die with .003-005” runout. I’ve eliminated the press(s) as well as the shell holder(s). I’ve tried a few different techniques I’ve read on here such as tightening the die ring with the case in it, no success there. I’m using Lapua brass and a Redding Comp Die with a Redding carbide bushing .002” under loaded diameter, no expander button is installed as of now. I have not neck turned this brass but my Mitutoyo mic tells me the neck thickness on this box of brass does not vary by more than .0004” (.01475“-.0150“). In my personal experience that should not be throwing concentricity off by that much, at least I have never seen it do it in the other calibers I load for, but I learn new things everyday so I’m open to ideas.

One other thing that is interesting is I know a local guy that had the exact same issue with the Redding bushing dies when loading for his 338 RUM. He tried and tried and never got it to work (he did turn the necks on his). His ultimate solution was taking a Redding FL die, running a carbide button way up into the die, almost to the neck, much like a Bonanza setup. He also ran the die .050” off the plate so it never touched the shoulder. For him this worked and has his runout back under .001”. I would like to make the die I have work if possible. I talked a bit with Dave at Redding and his only suggestion was to maybe try an intermediate bushing, say .370-369” and then go to the .366”. That solution does don’t seem ideal. Any advice on things to check would be very much appreciated, I would also appreciate any theory’s on what is going on here and why this seems to happen with the larger calibers.

Just some raw numbers

Loaded neck diameter .3685”
Fired neck diameter .373”
Bushing diameter ..366”

 

[pmarauder]

Well, i have your same exact set up.... TRG-42.... Redding comp bushing neck die....(.365 bushing) .372 chamber. I neck skimmed all my lapua brass to .0145. Im getting virtually no run out on a sized case, and only .0005 to .001 on a seated bullet measured where the rifling index's the bullet.

I also anneal my brass every other firing.

I have seen a bent decapping rod run the necks out.... but you dont have your expander installed.
Have you tried neck sizing with the expander installed?

Is your bushing installed with the .366 at the top? not sure if that would matter or not.
If you have another bushing..... install that one and see where your runout is at.
If you have more than 4 firings on that lot of brass, try annealing them. That might eliminate any wierd spring back issues you may be having.

( I just double checked my brass to make sure i was accurate on my runout numbers... .0005 runout on a fired case. .0005 on a neck sized case and .00075 or so on a seated 250 scenar)

Good luck and let me know what you find out

Derek

 

[Bast]

I had similar problem with .001 and I used a smaller bushing to have at least .002 of neck tension.

So maybe a .365 will be better.

Bast.

 

[RAGGED]

Well, i have your same exact set up.... TRG-42.... Redding comp bushing neck die....(.365 bushing) .372 chamber. I neck skimmed all my lapua brass to .0145. Im getting virtually no run out on a sized case, and only .0005 to .001 on a seated bullet measured where the rifling index's the bullet.

I also anneal my brass every other firing.

I have seen a bent decapping rod run the necks out.... but you dont have your expander installed.
Have you tried neck sizing with the expander installed?

Is your bushing installed with the .366 at the top? not sure if that would matter or not.
If you have another bushing..... install that one and see where your runout is at.
If you have more than 4 firings on that lot of brass, try annealing them. That might eliminate any wierd spring back issues you may be having.

( I just double checked my brass to make sure i was accurate on my runout numbers... .0005 runout on a fired case. .0005 on a neck sized case and .00075 or so on a seated 250 scenar)

Good luck and let me know what you find out

Derek

Derek, thank you for the great response. Dave at Redding also thought it could be a bent rod (this is a new Die strtaight from Midway, has sized 12 cases thus far) , as for the expander, mine did not come with one (did yours?), I have the carbide button kit on order. I have only fired 20 rounds thus far, so safe to say all my brass is once fired. I have tried a 364" bushing, and I have flipped the bushings with both that I've tried, no dice.

Did you try sizing them b/4 you trimmed the necks? I'm still waiting on the arbor from K&M otherwise I'd try trimming them down but I just can't see that causing .005" runout but I guess you never know do you.

Off subject, but how do you like the TRG? How many rounds thru it? What kind of groups are you seeing? Any pet loads? If you have the time throw a PM my way.



Bast- I thought the same and did try a .364" ( .0045" neck tension) and it did not help, in fact it was .001" worse.

 

[pmarauder]

Im assuming that you have taken the decapping rod out of the die to make sure it is not bent? Those things come loose very easy and if your not careful, they are very easy to bend. Always make sure they are tight before sizing. Im suprized that your decapping rod doesnt have a expander installed on it. the only time i take the expander off is when im getting ready to neck turn and then i run the case through the K&M expander which is sized accordingly to their turning mandrel.
You mentioned that you have a arbor on order from K&M?? Do you have a differnent die set you plan to use with the arbor press? or did you mean the turning mandrel?
really, the only thing that makes sense is that you have a nice concentric neck after firing....... and then you size it and it comes out .005 neck run-out. I bet its a bent decapping rod ...... let me know what you find out.

As far as loads go, i had a decent load with the 250 scenar with vv560, (88.5) just touching 2975fps 1/2 MOA at 200yds.... but i just switched to H4831sc because of price and avaiability. now im loading 89g with the same bullet @2975fps and getting SD #'s from 3 to 5 . with several 3 shot groups @100yds anywhere from .375 ctc and well below that.... one group measured one perfect hole at .3405 No Joke...... but some luck involved on that perticular group, but still nice to see. Now we will see if it can hold up at 300yds

Derek

 

[AB]

@ Ragged

I had the same problem with my Redding comp die, in 308. I found the problem to be, that i had to seize down 009, and it seems, that when you go over .005 you can get this problem.

There is nothing wrong with my chamber, it is a normal SAMMI spec. chamber.

I tried, to do a 2 step seizing, but then you have 2 x springback, and need a smaller bushing, for the final seizing.

I overcame the problem, by annealing before seizing.

I use the the same dies in 6,5 x 55 and 223 AI where i do not have this problem, but in those i do not have to seize down more than .005

Regards

AB

 

[RAGGED]

The rod seems to be fine, the pusher rides it very well. No expander on this set, the 243 comp die a got a little bit ago came with one, but not this one, just a naked decapping rod. I meant turning mandrel for my KM trimmer, sorry for the confusion, but while on the subject, would you mind tossing me the measurement of their 338 Mandrel. I have their expander at home but my local shop didn't have the mandrel and I didn't want to pay $9 shipping so I opted to wait till my local guy gets his next order in. If you give me the measurement I may jump on the lathe and spin my own basic one up just to find out if this is all or part of my issue. My carbide button kit should be in any day, I think those kits normally come with a new decapping rod, if so that should help me eliminate that as an issue. I talked to Dave again this morning, pretty nice guy and very eager to help figure this out. If the rod and neck turning doesn’t fix this I will be sending the die/bushing/shell plate into Redding with some fired cases.

I believe you on the .340” hole. I've got about 20 rounds thru this thing, no real load development, just had to shoot it when I got it. I ran 6 rounds of naked 225gr Hornady SP’s thru it over a mild (book min) load of H1000, at this point I was simply trying to break the barrel in a little, .020” off the lands, grouped, both 3 shot groups were well under an inch, about .6” CTC. The next 2 groups were shot with Remington Match ammo that came with the rifle, Lupua brass, 250 Scenars, both 3 shot groups were closer to .75” CTC, not bad at all for off the shelf ammo in a brand new rifle. I also had 3 groups of 3 loaded with 300 SMK’s, 3 over H1000, RL22 and 4831SC, all loaded to book min, 2500 FPS or so. The H1000 group was right at .5 CTC, the RL22 was a slight slight clover, .1 CTC, the 4831SC was one perfect hole, the hole was actually smaller than .338” as I was using shoot and see’s, a guys got to love that : ) That was my last group for the day, I wanted to leave on a high note. I would be absolutely tickled pink if I could get a cupcake load like that to hold together @ 1000, only time will tell. Have you tracked throat erosion? I’m curious to see how the forged barrel holds up over time.

Don’t forget to shoot me that mandrel measurement if you can, thank you!

 

[RAGGED]

@ Ragged

I had the same problem with my Redding comp die, in 308. I found the problem to be, that i had to seize down 009, and it seems, that when you go over .005 you can get this problem.

There is nothing wrong with my chamber, it is a normal SAMMI spec. chamber.

I tried, to do a 2 step seizing, but then you have 2 x springback, and need a smaller bushing, for the final seizing.

I overcame the problem, by annealing before seizing.

I use the the same dies in 6,5 x 55 and 223 AI where i do not have this problem, but in those i do not have to seize down more than .005

Regards

AB

Good info, that was kinda of what Dave was hinting at yesterday. Like you I use these dies for other rounds (223,243,22-250,7mag) and have never had an issue, but just like you said I have never brought one in this far with a bushing die. When you say annealing before sizing do you mean every time? This is once fired Lapua, factory annealed, I can’t possibly think that it would already need to be annealed again, every 4-5 shots is what I’ve heard as the norm.

 

[pmarauder]

Looks like the K&M Expander is .3365 and the turning Pilot is .3355

 

[pmarauder]

I also had 3 groups of 3 loaded with 300 SMK’s

Do you have the newer 1-10 twist on your trg-42?

 

[RAGGED]

Looks like the K&M Expander is .3365 and the turning Pilot is .3355

Thank you, I might turn up a pilot in the next day or so.

Do you have the newer 1-10 twist on your trg-42?

Yes, its a 1-10", green, 42X NXS CH3 ret, factory bipod/brake/3 ring mount (selling the mount) . I cant wait for the Berger 338 VLD's, hopefully they will work in the 10 twist but I if they don't the 300 SMK's are a pretty nice pill at .750 BC
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[ronemus]

How much are you reducing the neck diameter from as-fired to sized? I had this same problem in .223, and was advised not to size more than 0.003-4" per pass; you have to size 2-3 times using smaller bushings each time if you have a typical SAAMI chamber. I wasn't about to do this for the volume of brass I process (I shoot NRA Highpower and Long Range), so I returned the die. A bushing die only works well with a custom chamber that has no more than 0.004" neck clearance, such as the fitted necks used in benchrest.

 

[AB]

You must remember to correct the case mouth, so it is strait, and therefore do not tilt the bushing.

Next the annealing will not hold up in time, so it has to be just before you seize it.

New brass has to be worked, to get max result, but i use it for training/fireforming, and then work the brass.

Kind Regards

AB