I need some help explaining this one

[Guest]

OK, bear with me if this becomes a long post. Got out to the range today to test some loads for the 18th.

Anyway, Thought I would start with some once fired brass to see if I could get groups like the last time I posted.

did 5 shot groups different powder charge for each group for 20 shots.. Groups were pretty good but not as good as my last trip...hmmmmmm I did adjust seating depth as recomended by a few so I thought that was the problem. No worries...still good groups.

Then for the heck of it I tried the same charges as the groups above but this time used new unfired, Un neck turned brass. Just flash holes and primer pockets. WOW My groups shrunk big time. See my example below for vel etc.
on one particular load and group.

Once fired neck turned etc

hi=2849 low=2808 es=41 avg=2834 SD= 15

New virgin brass

Hi= 2840 low=2828 es= 12 Avg 2835 SD= 4

OK, Vel is pretty close on both of them...I know I could go higher but this is the load that seems to group the best right now. Why the difference in groups as well as Vel numbers.

Here is my thought. Neck turning is kickin my butt here. A wise Man C.M. /ubbthreads/images/graemlins/smile.gif told me dont even fool with neck turning. I figured I'd listen to him and got a better group.

I know there are more details involved but my thought is I was messin with hte brass too much and makin things worse instead of better. Also..The unturned new brass!! was all sized on a standard redding F/L die. No fancy neck bushings etc.

Needless to say come the 18th, I will have a bunch of loads from virgin brass and not really screaming. I know I need to do the test over to see if this is really an issue, but the groups just shrank on all the unfired new brass. Hmmmm did I just make the neck more sloppy by turnin?

Anyway...These are the things that just caused me an annurism (sp) and splitting headache for the day.

Your opinions are very welcome and needed.

Joe

BTW if anyone is curious about the groups...The new brass best group for 5 shots this time went into .3 easy. And thats doing it the way JB1000 and others told me about /ubbthreads/images/graemlins/wink.gif Worst group of the bunch all in all went into .5 Kind off disapointed me after seeing this thing shoot better. I know it's my loads and me and not the gun. Too funny, listen to me complain about a half inch group...You guys ruined me!

 

[308 nate]

lablover,
I don't remember what other people recommended, but here is what I recommend.


On your once fired brass with the necks turned,is to only size 2/3 -3/4 of the neck and then seat your bullets to touch the lands and maybe into the lands a few thousandths I have had really good luck doing theis in fact I would even do this on brass that was not neck turned.
FWIW,
308nate

 

[Buffalobob]

I guess several of us all did the same thing at once and started neck turning. Two points of difference in my amatuer understanding of the instructions. First was to uniform the primer pockets after the first firing. Secondly, I full lenght sized and trimmed the once fired cases before neck turning and cleaning up about 75-80%(stage 2 brass). Group size was not too good with this stage of the brass and grew about as much as you describe. At Mifflin with the factory off center chambered 17 Rem I shot the first two distances with stage two brass and the 500yd with the stage three final neck sized brass. Group size could not be measured at 500 yds because I was just adjusting left or right as JB told me. I do not know yet what group size the final brass is shooting

Being about as confused as you, I think there are two schools of thought.

School #1 With a factory chamber you should not neck turn because it just causes the bullet to be low in the throat.

School #2 With a factory chamber it is good to neck turn to get uniform neck tension on the bullet.

It seemed to me everybody was pretty consistent that with a custom chamber neck turning was good.

These are just my thoughts being as I am very new to neck turning and saw my group sizes grow as yours did and I hope mine settle back down.

In case you need to feel better, I ruined about $60 dollars of brass doing all of this wrong the first time. I just look at it as an investment in the future.

 

[Guest]

Great explination BB. Makes me feel better. I know I dont have a tight neck gun...But it is a Tight factory chamber, from what I understand.

I may leave well enough alone? But then again...That very first firing with the turned necks did produce great groups.

Monkey wrench in the whole thing is that the Range officer is a benchrest guru and said dont neck turn! Shocked be from a BR guy. Also, the position I was shooting for Chrony reasons ..the impact area is a huge wall next to it..He said it's hell next to that wall on windy days. He was surprised I got the groups that I did.

Joe

 

[257speed]

A lot of f-class and other long range riflesmiths have started using "no-turn" reamers. Seems with the good brass, neck turning is not so important.?. I sure don't know, but there is for sure a trend towards not turning necks at all.

 

[LB]

"School #1 With a factory chamber you should not neck turn because it just causes the bullet to be low in the throat.

School #2 With a factory chamber it is good to neck turn to get uniform neck tension on the bullet.

It seemed to me everybody was pretty consistent that with a custom chamber neck turning was good."

I think this #1 is accurate information. A very minor clean up, after FL sizing, helps on case neck uniformity. Don't expect miracles. But, if you don't know the chamber dimensions, you can't know where you need to stop on the neck turning. 25%/50% removed, for example.

For number #2, I can't agree with that. That applies for a tight neck in a custom barrel. In which case, you will probably know your neck O.D. and a good idea of your wall thickness, and can order those "fancy" bushings in the correct size. And, you may not get it right, the first time? This is stuff that does not apply for a factory barrel....usually.

In the case of a 220 Swift, for instance, you may see thickened and excessively long necks. Then, you need to trim to length, and decide whether to inside ream or outside turn, avoiding the dreaded "donut".

Good hunting. LB

 

[lynn]

Lablover

What you are experiencing with new brass is quite common.In general new brass will give lower velocities with the same powder charge because the brass expands to fit the chamber.Once it is all fireformed velocity will stabilize and your load will need some tweaking to reach best accuracy.
I don't know which case your using but i suggest you use a 1% increment when working up your load.If your shooting 50 grains of powder vary the charge weight in 0.5 gr increments.
I also suggest you load your ammo with the bullet seated out for enough so that closing the bolt actually pushes the bullet back into the case a very small amount.This will allow you to safely work up a very accurate load.
You can now do your ladder test to find your particular guns load window or node.The load window or node is related to the amount of powder your case uses.The bigger the case the wider the node.Once you find two or three bullets in a small cluster you can fine tune for best accuracy.It will generaly be found in the upper half of the load window.
As an example to help in the explanation we will work with the 300 Ackley round.Shooting a 216 gr bullet and starting at 75.0 grains of powder we will go up in 0.7 grain increments.The bullets will be seated extra long so the bolt pushes them into the case and we will go to the range with 10-12 rounds to be fired at 300 yards.We will now shoot 3-4 rounds at 75.0 grains to get on target and to warm up the freshly cleaned barrel.As we start shooting we notice a very definite vertical stringing at 75.7 76.4 and 77.1 grains.When we shoot 77.8 78.5 79.2 and 79.9 we notice that the vertical is gone even though the powder charge has varied 2.1 grains.
From many years of testing we know the best accuracy will be found in the upper half of the node or load window.We will now start somewhere near the middle say 79.0 grains and go to say 80.3 grains in 0.3 grain increments shooting 3-5 shot groups.We haven't touched are seating depth at all.At 80.0 grains we discover our best accuracy.The 3-5 shot groups look like little round clusters not tall skinny ones.
From this point we can now vary the seating depth deeper in 0.005 increments because we already have the bullets seated out as far as possible with the existing neck tension.
The key here is one step at a time and finding the optimum point at each step.
Lynn

 

[Guest]

Not sure how much neck turning you are doing....

I personally hate to turn necks.. ie: for a specific throat dia. HOWEVER,

I "turn necks" only to make then uniform... meaning.. i just take enough off of them to make them more specific. Typically when I am done turning alot of my necks only have some brass shaved off on one side... I am after uniform thickness not a specific dimension.

as far as your velocity.. you are right on the money.. I have found that with the 6.5/284's I have had anything over 2900 fps may tend to decrease accuracy... so to speak....

FWIW....

 

[Fiftydriver]

Lablover,

Not sure the specifics of your set up but I will tell you that I have found that with factory rifles, what we think would be the most consistant loads using quality snug fitted brass often do not produce the finest accuracy.

In fact in many factory rifles, I have found that a full sized case that basically falls into the chamber is the best shooting load, why??

Well, in many cases it is because the bolt locking lugs are not contacting evenly and when a snug case is chambered it preloads the bolt body at a cant.

I don;t know if you have had your rifle trued up or not but this is not uncommon from what I have seen in many factory rifles.

I had a Ruger 220 Swift one time that I could not get to shoot under about 1 moa. This was a heavy barreled varmint model. This was many years ago and I tried every load I could think of with no good results.

Finally my brass was beginning to wear out so I ordered in virgin cases and loaded up some 50 gr Ballistic tips and oddly enough they averaged under 1/2 moa for five shots????

Second loading they averaged 3/4 to 1 moa so I set down to figure out what was different. Then I full length sized the hulls and things dropped back down to 1/2 moa or less.

Since then the rifle has been trued and this is not a problem any more and it is now a 22-6mm AI but I have found this with many factory rifles.

Something else to look at.

Kirby Allen(50)

 

[Guest]

Great advice so far. It's a head scratcher for sure. I was cleaning up the necks as well. 70-80 % of the neck was hit.

Heck, I even had some loads left over from the very first loading and theydid not do as well as the first trip. So, It could be me. I did notice myself canting alot but not sure how that was affecting me at 100 yards. Also the wicked wind the R/O spoke about by the wall

Fifty..Yes, the action has been trued etc.

I'm gonna do some more shooting and go from there. Hey, if I dont need to neck turn, then why bother. It's not a tight neck or anything. I just want to find a load and shoot. I really dont want to get wrapped up in too much testing with this gun. 5 shots under a half inch is more than good enough.

Well, thats what I say anyway /ubbthreads/images/graemlins/smile.gif I'm gonna run the test again and go from there.

You get so involved with i.e. jam it into the lands...Leave it .20 off the lands...YIKES! Enough to make ya crazy.

Almost forgot to mention. This is New Lapua Brass

Take care

Joe

 

[jb1000br]

Joe -- for some reason, the best groups ususllay come during fireforming.

THat is why i have no qualms FL sizing every time!

what is your neck diameter? 297 im guessing?

If i had a no turn neck, i wouldnt turn either (building a no-turn 6br right now)

i'll take your once fired brass if you are going to stick with virgin only /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

JB

 

[Guest]

sounds right on the neck.

Just did some resizing now and will see what happens. Funny thing, I yanked the expander ball out of my F/L resize die Sized a few case and had ZERO run-out. This is with the Redding standard die. Think I'll try that instead of my Redding type S F/L bushing die. Heck...Who knows right. I'm curious to see what the once fired no neck turn stuff does..

Joe

 

[3sixbits]

I don't know how neck turning can do anything but hurt you in a barrel with factory dimensions. I have always found best neck clearance to be in the area of between .0005 and .0015, on a side. Why people will jump into neck turning without a clue as to what the real chamber dimensions are is a mystery to me. Is there some kind of religious prohibition against chamber casting? How does it make it more accurate by adding more slop? If you try telling me that it is to make the necks more uniform, then I going to tell you, you've already got a problem with lopsided brass that neck turning is not going to help. Does anybody wonder why short cases tend to shoot more accurately than long? Could it be because it's easier to make a short even thickness case than a long even case? /ubbthreads/images/graemlins/grin.gif

 

[Buffalobob]

I see School of Thought #1 has weighed in.

Some of us just have a lot of frog chromosones in us and "will jump into neck turning without a clue".

Yes, it has occurred to my to try to remember where I put the chamber cast for the 240Wby.

As far as religouis prohibitions goes:

I do believe that God did issue some instructions on neck turning and Lot's wife ignored those instructions and turned her neck and as punishment God transformed her into a pillar of salt. So 3sixbits it does seem that you are right /ubbthreads/images/graemlins/grin.gif