Hello folks,
First I want to thank Agrivere for his explanation of some of the ins and outs of handloading. My groups have shrunk to a little less than 1 moa. They would probably be better if I was willing to load past what would fit in my magazine. But I have a different question, D Tubb stresses the importance of neck turning the brass. Since he has won NRA Highpower matches many times, I'm not qualified to argue with him, so I'll give it a try. Question: how much?
This is where I'm starting from: SAAMI specs is 0.3435. A measure of the outside diameter for the cases I'm using is 0.3340. Inside diameter is 0.3030. Buller diameter is 0.308. Walls are 0.0177 (math). I'm trying to find a finished dimension.
Zediker gives 0.0140 wall thickness. Reverse engineering that number, I get 0.0280 as the sum of the thickness of both walls. Adding that to 0.3030 (inside diameter I get 0.3310 as the desired dimension. Is this correct, or should I be using bullet diameter? Or should I be using a different set of parameters?
Thenks
AJ
First let me say I'm glad some of my other posts were helpful!
Now, as to neck turning, several thoughts come to mind. First and foremost, no competitive shooters I know of bother to turn necks at any range less than 600 yards, and even at 600 yards the value of turning necks is questionable. Remember that David Tubb's shooting has as far as I'm aware always had a large focus on shooting at 600 to 1000 yards. At those distances neck turning takes on greater value.
Having said that, I've certainly done it and gotten good results. By good results I mean that the necks turned nicely and my runout gauge told me the loaded rounds were nicely concentric. Based solely upon feel when seating, I would also say neck tension was vey consistent. So in short, neck turning will indeed help you improve the quality of your reloads. I would not, however, at least in my personal experience, expect to see anything show up on your targets.
The cases I neck turned did not have any better results on target that I could determine, given the other variables in play (my hold, the wind, eye fatigue, etc). I'm sure in a sufficiently controlled environment one might see a difference, and I'm sure David Tubb could see things that I would not see, but at least for me, with my rifle, I could not see any difference. So this is a reloading step that I don't generally bother with anymore.
So, getting back to the how to do it part, the amount you want to turn your necks should be determined by where you're starting. I would not worry about 0.0140" as any sort of "goal" for wall thickness. You "can" measure the wall thickness with your calipers, and you "can" calculate a "typical" wall thickness using the math you've done, but if you really want to turn necks a ball micrometer is so useful as to be nearly essential. This tool allows you to accurately measure the wall thickness of your brass.
You'll find that wall thickness will vary quite a bit. I mostly load .223, but even in those small cases a batch of Lake City brass might have a neck thickness of around 0.011", and a batch of Lapua brass might be more like 0.015". Other brands will vary a great deal.
So when I approach this task, I get out my ball micrometer and start measuring some case necks. I want to see what an average or typical thickness is, and how much it varies. If the cases are good, it should not vary by more than a couple thousandths of an inch at most, and some cases won't vary much at all.
What I'm looking for is what neck thickness will allow me to remove MOST of the variance. So to use a recent example, if I'm measuring my batch of LC12 .223 brass, I find that the typical neck thickness is about 0.0115", and that it varies from that by about +- 0.001". So I'm finding virtually all of these case necks to be between 0.0105" and 0.0125". I then set up my neck turning tool to turn the necks down to 0.0110". That's enough to remove MOST of the variance, without creating more unnecessary work for me or making the necks too thin. If it's setup right, neck turning should seldom remove brass around the entire circumference of the neck, just the high spots.
It's also important to make sure you prepare your brass properly before you do, since any concentricity issues that exist before neck turning will only be worse after. When I'm neck turning, I size my brass with a full length Forster sizing die, with the expander ball completely removed. I then use a separate expander to expand the necks up to the correct inside diameter for neck turning. Using the full length did without the expander ball virtually guarantees that any imperfections in neck walls will show up on the INSIDE of the neck after sizing. You should be able to run the case neck at this point over your concentricity gauge and see runout that's almost zero. If it's not, go back to step one and figure out why your sizing die isn't sizing right.
Once that's done, I'll get out my expander mandrel, and run that down into the case. This should set the inside diameter of my case neck to the correct diameter for the turning mandrel, as well as move any case neck imperfections to the OUTSIDE of the case, which is where we want them. You should end up with an inside case neck that's perfectly concentric with the case itself, and the outside neck should have all of the case neck imperfections. This you can also measure with your concentricity gauge. What I'll do is use the ball micrometer to measure how much variation there is in the neck wall, and then put the case on the concentricity gauge, where I expect to see that exact amount of runout in the case neck. So if the neck wall varies from 0.0110" to 0.0125" in thickness, when I put that case on the concentricity gauge I should see almost exactly 0.0015" of runout, which corresponds to the variation in case neck thickness.
That case then goes on the neck turner, and when done you can once more use the concentricity gauge to check your work. The now turned case should have zero runout now on the outside, other than the potentially small amount of brass that did not get cut. If I'm seeing more than 0.0005" of runout at this point, I may need to adjust the neck turning cutter to cut a bit more. If I'm uniformly cutting brass all the way around the entire neck, I might adjust to cut a bit less.
Hopefully that makes sense, feel free to let me know if you have any questions!
There is, btw, a very simple experiment you can do to determine whether or not neck turning will help you improve your groups, and it doesn't cost nearly as much as all the stuff you need to actually turn necks.
Buy a box of Lapua brass.
Load that brass.
Shoot them.
See what you get.
I've measured a lot of brass, and I've never seen even one piece of Lapua brass that I thought would benefit from neck turning. The necks are extremely uniform in thickness right out of the box, generally measuring less than 0.0005" of thickness variation. That's about as good as you'll be able to do with neck turning, and you don't actually have to do all that work.
So if you want to see what the benefits are without actually doing all that work, buy a box of Lapua brass and see what you get. I'm betting you won't see any difference, but if you do, at least you'll know one way or the other!
Dear Mr. Agrivere,
When we be able to purchase your precision reloading book?
Meant only partly in jest, your answers to reloading questions are thorough, well thought out, and make sense.
Thanks for what you do.
It's not so much a matter of neck thickness as it is concentricity and UNIFORMITY!
If you really want to be a perfectionist (or just plain anal about it), you start with cases from one manufacturers production run, once fired. You then weigh them individually, and separate them by weight, based on your predetermined specifications, such as +/- .5 gr. Once that is done, deprime only. No resizing of any kind.
If maximum accuracy is your ultimate goal, the next step is to uniform the primer pockets. Follow that by flash hole deburring. Strange but true, just those operations will improve accuracy!
Follow this by neck sizing, only. Then, gently start outside neck turning using something such as a Sinclair outside neck turning tool, Manually! Set the cutter to just barely shave brass, and stop just at the neck/shoulder juncture. You'll find you have high & low spots. Using a tubing micrometer, check for concentricity. Adjust the cutter as needed and repeat until the neck is concentric and no more!
Follow these procedures on all of the cases in a particular lot. They should be from one rifle, only! The one they're going back into. Size only enough to chamber in that rifle reliably.
As an aside, let me mention that doing the primer pocket & flash hole prep (both one time operations) followed by sizing in my Dillon power trimmer and NOT EXPANDING the case necks at all, I get more uniform bullet pull without neck turning.
Accuracy on my M1A Super Match increased very visibly immediately upon doing the Dillon trimmer thing. Ditto, my Rock River A2 NM AR.
Strangely, using a ancient Lee Benchrest Loader with an inside neck reamer, I accomplished a remarkable 0.239" center to center ten shot group at 100 yards with a dead stock Remington 788 in .243 Win.
You mentioned using a magazine, which indicates the possibility of an autoloader. You're never going to achieve optimum accuracy with a gas gun. Bolt guns are it, but using the above techniques, you're going to get as much as you can out of what you've got.
I enjoy embarrassing bolt gunners at long rang matches using my M1A and it's crude 1/2 minute sights.
Try it.
Good luck!
Sightwolf O0
I really appreciate all comments/suggestions. Thanks folks for taking the time to share your experiences.
The rifle in question is pretty much a stock rem 700p. I swapped the stock for a chassis so that now it feeds from mags.
Right now I've come up with an SOP (but fine tuning never ends) for handloading. It seems to work adequately, but, being a rookie, I always seem to run into speed bumps. And is very slow going.
Because I only have access to a 100 yd range (my shore passes are short) I don't expect to see any improvement with a magnitude that will water my eyes, but I enjoy the theory behind the process (inquiring minds like to know).
Thanks again, Agrivere and Sightwolf!!
Jose
Update: I just returned form the range. Fired 22 rounds I had reloaded including the neck-turning drill. As Agrivere had predicted, I could not detect improvement in group size, but there was a decrease in number of flyers and even those were within kill parameters on a hog. Overall I had a 0.7135" MOA and none of the flyers (2) was more than 1 1/4" off.
Rifle is a Rem 700P (in .308) win with an AICS chassis. Prone position with a bipod.
I'm now trying to figure out concentricity. In laymans terms, circle within a circle, How is runout related to it? Is it a different gauge?
Thanks!!!
AJ
Runout is checked with a different gage.
LOL, Agrivere and I (likely him more then me), have gone down this road of "chasing the reason", with reloads. As stated....if only shooting 600 yards and in, neck turning is personally a waste of my time. I bought the tool, looks like a very nice paper weight on my bench. If I ever get into PRS or F Class or NRA Palma, it will get utilized.
Concentricity....yup, Hornady sells a nice tool for that.
I have found...that a good press, and reputable "match grade" seating dies....pretty much negate the need to check concentricity (600 yards and in).
Now..., it depends on the rifle also. I did this simple experiment a few months ago for my M1 Garand. Loaded a bunch of ammo for Camp Perry. I then checked the runout, and it was good! .002 at the most.
Then a friend told me to load that ammo in an Enbloc clip, and load into the rifle. And just cycle the bolt and eject all the rounds.
Then check the concentricity! It was like .005/.008"!!
That is due to the VIOLENT action of the Garand, and I assume the results would be the same with pretty much any semi auto rifle.
So....concentricity/runout.....IF shooting 600 and in, and are using reputable seating dies (Redding/Whidden etc).....don't sweat it. If shooting past 600, in a BOLT action....maybe worth checking and adjusting it.
I have pretty much abandoned my OCD/ADD/ADDHD reloading processes for the 600 yard line and in. My recipe is 77 grain SMK's loaded to mag length with 24.0 of RL15, in WOLF already primed brass. Those work very well, and save me a lot of time.
600 yard line ammo is 80 SMK, Lapua brass, CCI BR4 primer, COAL is set to .015" off the lands, 24.4 grains of RL15, CCI BR primer. Works just fine.
FWIW
R/
Chris
You mentioned the Lee Benchrest press, is that what you use for all steps of the reloading process?