measuring bullet runout

[deadlyswift]

Laurie
Thanks for clearing me up on the flashole burrs. I have seen a huge differance in brass wieght with win. brass. I sorted 100 pe of win brass and ended up with 4 groups of brass sitting on the bench. Then after I uniformed the brass I was able to get it down to 2 groups weighing at least .9gr of one another. One group had 35pe and the other 65pe in another group. Again thanks for the info.

 

[fdshuster]

Bob3700; yes I did suspect the main cause of the 222 Rem runout (Lapua brass) was the long neck length, compared to the 223 Rem (also Lapua) that is so much shorter, could not prove it, but your thoughts make me feel a lot better about the cause. The 222 is essentially a 200 yd. cartridge anyway, and groups are always sub moa, so it was no big deal. I do break the sharp corner on the Lapua primer pockets when prepping new brass. Just a very small 45 degree break angle to start the primer into the already very tight primer pocket. The cases are all inside taper neck reamed with the K&M tool, usually a one time thing, since there is very little, or no stretching with the required trimming to length. Great series of postings here, and to all I thank you for your thoughts & experiences/ I continue to learn.

 

[GermanS1]

The thick side on the neck often - but not always - stays thick as you go down the case. NECO and Tom Titcomb make nice tools to check this and I have a little article about them here.
http://riflemansjournal.blogspot.com/2009/07/reloading-audette-neco-case-checker.html

Like so many other good ideas, this tool originated from the great mind of Creighton Audette. I can definitely say that when using a two-lug action, the checking and indexing procedure developed by Audette with the tool really helps accuracy.

 

[AlNyhus]

The inner case neck is an overlooked cause of runout issues. The assumption is that they are straight and round. This is rarely the case (pun intended).

No need to bore anyone with the how-to's, but I consider making the inner case necks perfectly round...and perfectly straight...to be the single most important thing I do when prepping cases.

 

[Bob3700]

Swift,

I would do your last step first and then put the effort into brass that has even distribution in the walls. Saves you a lot of work, only dealing with "Brothers" you want to shoot.

The others you can use for practice or sight-in.

German is correct that the thick/thin sides of the brass begin at the head and run all the way to the neck. The difference in brass thickness is a bit more pronounced at the base than the neck but you could still check necks for thickness variations and sorting.

Like AlNyhus, the last step in my brass prep is to run my necks over a sizing mandrel. This ensures the ID of the necks are all the same diameter and as round as they can be. You are also setting the neck tension with this last step.

Bob

 

[Bob3700]

ALNyhus,

I believe you are right on the money with the ID of the neck being so important.

Everyone turns the outside of the neck on a mandrel. What assurance do you have that the neck is in line with the case body?

Years ago, Merrill Martin put forth the idea that to make you necks really straight, you need to line ream them in a FL sizing die. Hunnington Die used to make just this set-up. Insert the case in the special FL sizing die and then a chucking reamer was inserted from above. This actually made sure your necks were uniform and in-line with the case body.

I think he had the best idea.

Bob

 

[GermanS1]

Bob, I think those reamer dies are still available, I'll have to check.

Al, I would consider a "how-to" on your methods anything but boring! If you have the time to type it, I'd be very interested to read it.

 

[AlNyhus]

Hi, German. The Huntington Neck Ream Die setups are still available from them on a special order basis.

Good shootin'. -Al

 

[alf]

the last step in my brass prep is to run my necks over a sizing mandrel. This ensures the ID of the necks are all the same diameter and as round as they can be. You are also setting the neck tension with this last step.

I found this adds to the runout.

All this talk about runout is the reason I don't shoot no-turn necks.

Also, I straighten all my competition ammo, sighters and record both.

 

[GermanS1]

Thanks, Al! I'll call today and see if they're in the "affordable experiment" category. Would be nice to play with for my .30-06 long-range stuff.

 

[Bob3700]

ALF,

I guess that I have to ask why you turn your necks if you still have to straighten them once the bullet is seated? If the neck isn't straight after turning, perhaps it is a step you can delete.

Just seat a bullet and then straighten the loaded round.

Bob

 

[alf]

Bob,

First off, it's a .269" necked Dasher. As good as Lapua brass is, it still benefits from turning. Maybe not for varmints, maybe not for f-class, but for me, yes for 1000 yard Benchrest. In good conditions, my loads did 1/4" moa during development at 300.

My comment on running a mandrel in the neck inducing more runout is what I found on a 22-250 I was struggling to tighten up the groups with, not my 1000 yard guns.

After every firing, I anneal, full length size and straighten everyone after seating. I try to get as close to zero as I can. And I keep the mandrel and/or sizing stem OUT of the inside of the neck.

This year I set the IBS 1000 yd light gun world record for the six target agg with a 4.2xx", which included three screamer groups. You guys can do whatever you want. I know what works for me.

Al

 

[mikecr]

I agree with the posting about checking thickness variance first in brass culling. No sense prepping brass that would end up bananas down the road. Just rake them in a can, minus a few to set your turning cutter with.

I don't agree with die sizing anything during preps though. No need for it(unless there is), and it's detrimental for sure to downsize necks before turning.
The last sizing(if any) before turning should be upsizing necks for the correct turning mandrel fit. Case concentricity really doesn't affect turning. Atleast, it's not an issue using the Sinclair turning system, as long as all is floating(per design).
You might also employ this 'last is upsizing' before seating bullets. I use Sinclair's mandrel system for this, as it pushes any remaining thickness variance outward, can normalize tension(I measure tension here), and does not misalign necks like buttons.

After fireforming, as pulled from the chamber, I further check and cull by H20 capacity. I don't weigh brass..

Believe it or not, 3 other things I don't expend time with is trimming necks, pocket 'uniforming', or flash hole cutting. I have not needed to trim, so I don't. I don't believe the slight difference in flash hole or neck length variance amounts to diddly. And I measure actual primer crush while seating them with a K&M seater. So there is no reason for me to mess with the pockets.

Just some contrast for ya

 

[Bob3700]

Al,

You accomplishments are to be applauded. The on target results you have gotten speak for themselves. You methods do work for you.

I still would like your thoughts on why you specify a tight neck that requires turning and when you are done, seated bullets still need to be straightened?

My question comes in an effort to learn what brass prep is really necessary for good accuracy and what is unnecessary. How many steps do we perform because according to THEM, "That is what has to be done for accuracy".

I believe what you have found is that bullets loaded with zero/low runout produce small groups. Audette confirmed that with his work.

My contention is that outside neck turning is great to make the neck thickness uniform but does not accomplish the task of making the neck straight with the centerline of the case. That should be the real goal. The bullet straightener, while accomplishing your goal, is treating a symptom not the cause (banana cases).

That said, your technique works and your results prove that. There are different ways to skin a cat, in the end, the cat is still skinned.

Bob

 

[AlNyhus]

alf: My belated congrats on your IBS World Record! You're always one of the top shooters, no matter what the game or yardage. 8)

Hope to catch up with you this season at Van Dyne. -Al

 

[GermanS1]

Bob, you're right on the money, let's attack the cause, not the symptom. The Audette tool is very useful for this and I've been able to replicate Audette's results in terms of orienting the cases and seeing the shots go in the direction of the curve. The 3 and 4 lug actions like the RPA, Gilkes, BAT 3L, and some others, reduce this effect, just as Audette postulated and that is a partial solution for something like Palma shooting since we are unable to ensure proper indexing for each shot in the heat of competition.

There is a lot of voodoo and superstition in case preparation (not tomention other aspects of reloading). However, as a few, including you, have mentioned, it is well worthwhile to conduct careful, well designed experiments to determine what will and what won't have an effect on our desired outcome. That is exactly how I try to spend my non-competitive shooting time and I have found it to be a never-ending source of satisfaction.

 

[alf]

Thanks Al, means alot.

Hope we can butt heads this year too.

Bob,

I think overall, the tight neck and turning reduces the runout over no-turns, not eliminate it. Another reason to anneal, I think it makes seating pressure more consistant. Running a mandrel in a neck to try and get consistant neck tension, does nothing to eliminate the uneven bullet release in a case with uneven neck thickness.

You'll also find that the runout mostly is in the neck, showing on the bullet. If you check the neck also after straightening, the neck was straightened, not the bullet's orientation in the neck.

Now, why are the necks getting bent? I believe it comes from the difference in brass thickness carried on down the shoulder to the body, which contributes to the banana effect. So when full length sizing, the neck, shoulder and the front half of the case is tweaked out of alignment. Straightening brings it back. Mostly.

All my Dasher brass is shot once in a no-turn chamber shooting prairie dogs. Then it's detailed and neck turned. I still find the brass need another firing before load work shows it's merit. I don't weight sort, or sort by neck variance.

I shoot to have fun, but I fully expect to win everytime I set down. My techniques work for me. I'm not gonna change in the interest of saving time. I don't expend the number of rounds that German does, so I can afford to be a little "persnickity".

Al

 

[Bob3700]

Al,

I am enjoying our discussion very much and trying to digest what you are saying and thinking about your methods and their effect.

I shoot a BRX with a no turn neck at 600 and 1000yds in an NRA LR rifle. One of the issues that I pay a lot of attention to is neck tension. I believe that is a real key to accurate ammo. As you know, the neck tension changes as the brass continues to harden with each firing.

Rather than anneal constantly, I have a selection of mandrels that I control neck tension with. With in-line reamed brass, you begin with straight necks and your bullet run-out is low right off the bat. No need to straighten the neck on the loaded round. My match ammo averages .001" or less runout.

At this point, I don't even check it anymore cause like you, my system works for me. I can say that I have not stopped looking for the "Holy Grail" when it comes to better ammo, but I think I benefit from shooting more in the wind and learning to deal with that more effectively.

Great ammo will still shoot an 8 if I am not reading the conditions correctly.

Thanks for your thoughts.

Bob

 

[aJR]

Hi All , I spend a great deal of time making sure that the cases i use for the record target are a perfect as i can get .. I make the gear to check this ,if your checking each case before firing it is noticeable that all is not equal when it comes to brass.. I have had cases that were not usable and went to barrel warmers and after 1 shot it was just about ready to go to the record. They Move constantly at the pressures i run.. I do not have the luxury of the LAP 6BR case to start with .. All brass is not created equal ,some of it is just hard work .. My Case starts as a LAP 300WM ,i use a Krautkramer Branson CL3 ultrasonic thickness gauge that allows thickness checks all over the case .. This shows some areas that cause the banana problems and i still go through the long drawn out process i use because it nets on average a 90 % success ratio .. JR..Jeff Rogers.. it is quite interesting to see how bad case head squareness is on some brass..

 

[JRinCo]

alf,
in regard to the Dasher. Your method is to fire them in a no neck turn chamber before turning them.

This is my first Dasher. I'm wondering if it would't be as good or better to turn the necks first, right out of the box after sorting them for thickness variance. If you go say an extra .010 down a 6br neck and then fire-form, you have added some extra uniformity into the shoulder. Since we are only removing .0015 it could be a good thing.

I'd like to hear your thoughts.

JR