Case prep and step by step reloading

[Brad Y]

Dave, I cant wait to read the book that you guys are going to publish about building, tuning and maintaining f class rifles. The amount of scientific stuff you guys have done is just unfathomable.

[ned kelly]

G'day all,
all very nice but has anyone actually tested a bunch of un-weighed cases to weighed cases to see if there is any difference in accuracy/grouping?
I haven't noticed anything to get excited about re weighing & sorting cases in a BR rifle or my FO rifle for that matter.
Me thinks the time is better spent on the mound learning to read wind..........
Just a thought........
Cheerio Ned

[johnk]

Seems to me that winners replicate painstaking procedures preparing ammo, all their gear if it comes to that. The trick is identifying what of the steps they take are worthwhile and everybody should use & which ones don't contribute except to their peace of mind & can therefore are things that you can ignore.

[DaveMc]

G'day all,
all very nice but has anyone actually tested a bunch of un-weighed cases to weighed cases to see if there is any difference in accuracy/grouping?
I haven't noticed anything to get excited about re weighing & sorting cases in a BR rifle or my FO rifle for that matter.
Me thinks the time is better spent on the mound learning to read wind..........
Just a thought........
Cheerio Ned

What do you reckon Ned????

As I said I will discuss first but the long and the short of it is it doesn't matter at <700

[Cameron Mc]

Ned, where all the small things we do show up is back at the longer ranges. Good accuracy at 1000yds takes work to achieve, but to get good and consistant accuracy at the longer ranges takes more effort.

Cam

[ned kelly]

G'day All,
agreed any error/anomaly will show up more clearly beyond 800 and as the bullet slows more so at 1000.
My loads seem to work very well at 800-900, not shot 1000 yet. For me personally it is practice rather than weighing cases that is more important.

Perhaps if I can practice more I could see the difference that would make me consider weighing my cases!

Interesting topic nonetheless

Cheerio Ned

[IanP]

Ian- yes Im still waiting for the trimmer to arrive and have a heap of cases sitting waiting for neck reaming. Though I do like the sound of what Alan is doing and only sizing a certain amount of the neck so the donut wont affect the tension on the projectile. My chamber is only 20 thou shorter than his but with hybrids jumping I cant get away from the donuts.

Brad, one other thing to keep in mind on the subject of donuts is that the restriction formed is affected by your sizing method. If you check your fired cases by passing a bullet down thru the neck using your fingers to push the bullet in and take out again. A donut restriction may not be noticed if you only neck size your cases, but I use a Redding body die and then neck size and finish by using a Wilson seating die.

I find that after I body size my cases that the effect on the shoulder of the case makes the donut restriction obvious to the pass the bullet thru neck test. If you are just neck sizing cases then the restriction may not be affecting bullet seating pressure at all.

You raise the point of only partially sizing the neck, a practice BR shooters have been using for years and the Wilson neck sizing dies seem to be designed for this practice. If you use a Redding Type S just loosen off the neck sizing bush to achieve the same result.

Alan may be ignoring the donut restriction because it is not affecting his bullet seating tension by not seating the bullets down to the depth where they would be "pinched", but the donuts are still forming in his cases. Neck turning back into the shoulder like inside reaming stops the donuts from forming quickly but fire off enough rounds with the same case and the brass will migrate back eventually and require reaming.

One final point, by using the Wilson seating die and a Sinclair arbor press you can feel the bullet seating tension between rounds as you load. If you have any restriction, (donut, whatever) it will be felt instantly on the low mechanical advantage of the arbor press. If you seat bullets in your RCBS, (or whatever) high mechanical advantage press you will not feel the difference anywhere near as much as the feedback from an arbor press.

Ian

[Norm]

Hi all.
I do most of the same steps as everyone else, but just wonder if all the case prep actually results in lower ES and SD?
Now I have the Magneto I might set up a few cases prepped with different
procedures and see just how much difference in velocity it actually makes.

[DaveMc]

John K - yes - we (ironically) did all this work to see how much work we could save ourselves.


When doing experiments like these it is critical to have a knowledge of how everything interacts to give a final result.

The final standard deviation of either velocity or group size is the combination of many smaller factors. These are not additive!!! In fact it is more of a square root of the sum of the squares relationship.

What this means is it is very difficult to pull out one factor and see an impact on the final sd or group size. There is too much noise from the other factors. You actually need to do an experimental design that gives a "relationship" or correlation between shot height or velocity and the factor (e.g. shell weight).

e.g. in this case (sorry for the pun) do not simply do a comparison of group size (or velocity sd/es) of sorted and unsorted cases. Rather plot a regression line of sorted weight vs velocity (or plot height). You will need at least thirty shots to see the trend. It will have a low correlation coefficient due to the other factors causing velocity spread as well but the trends are important!!!

We did this several times with 30 or more shots in different rifles and the result was almost exactly the same gradient each time.

The old sayings we keep hearing over and over are spot on in my book
1) It is the sum of all the little things that matters (well in this case the square root of the sum of the squares)
and 2) B,B,B,B. Barrels, Bullets, Bedding and Brass!!

[AlanF]

Dave,

Our thoughts on this are very similar. Nearly everything we do to improve accuracy will to some degree help to reduce that final most important SD being distance from the middle of the target. The question is which accuracy endeavours give the best "bang for the buck" in terms of not only money but time spent. For example I've decided that measuring powder to within 0.05 gn is good enough because ladder testing shows that this equates to about 2 fps. Looking at case weights, I've calculated that 1 gn of brass represents about 0.17% of case volume, which will cause a little more than 1 fps velocity variation. Ned makes a good point about time spent practising. It is a major thing we do to improve accuracy, and needs to be prioritised along with everything else.

BTW have you Peter and Marty done any scientific research on the effect of stock pimping on accuracy? This is an area where much time and effort is spent (particularly in the regions immediately west of Victoria), and it'd be interesting to compare say 30 shots pre and post-pimped.

Alan

[Brad Y]

Ian- we are on the same wavelength. I FLS with a whidden die for 1 thou bump and have a wilson bushing in the top for the neck. Tonight I backed the top off to let about 2/3 of the neck size and the bottom half with the donut not size. I also use a wilson micrometer seater and everything felt very consistent- more so than normal. I might adapt that technique based on the results over the next few weeks.

I have seen donuts form on 223 cases used in bushing dies before, so no doubt they could form on any case whether its neck turned or inside reamed or not.

[SuperV]

Well which is better. Neck turning or inside reaming.

[ned kelly]

G'day Super V,
imho neck turning is better because you have full control on the amount of brass you remove, also it turns the brass CONCENTRIC with the inside of the neck, whereas reaming follows the hole and does nothing for concentricity - you will still have uneven wall thicknesses and you also need to use the Wilson type trimmer to ensure you are not out of alignment when you start or you risk "belling" the ID of the case neck i.e. wider at the mouth than deep in the neck after reaming.
I only ream to remove donuts and then I step it up 1 thou at a time, I DO NOT want to touch the sides of NT cases, only the donut, otherwise you rip into you nicely turned case necks and undo all the goodness.
Food for thought,
Cheerio Ned

[IanP]

Well which is better. Neck turning or inside reaming.

How long is a piece of string? Basically they are used for different things with neck turning usually being used on brass in tight neck chambers and/or on brass with inconsistent neck wall thickness.

Reaming is usually performed on brass with necked up cases, eg, 6.5mm necked up to 7mm brings thicker shoulder brass with it into the base of the neck.

Neck turning into the shoulder is more preventative and reaming also performs a preventative function but can also be used to remove the base restriction (donut) at any time. I have used both techniques and now just ream after the first firing of the case in my no-neck turn chambers. Obviously if you have tight neck chambers you would neck turn into the shoulder as well as thinning the necks for chambering.

Ian

[SuperV]

I only load for the boring old 308 tr. I'm using lapua " Palma" brass.