What am I doing wrong??? ES difficulties.

[SOcalsurferx]

Looking for a little precision wisdom.
My all -around load I developed a few months back for a new Krieger barreled, Surgeon .308 win is the following:

Lapua Brass - Neck turned, primer pockets uniformed, nick sized with Redding .336 bushing

Wolf LR Primers

Sierra 175 SMK, meplats trimmed to uniform, Seated to .020" Jump

44.7 gr Varget, each charge weighed to exact weight on RCBS Chargemaster.

Chrono is a CED unit, placed 12 ft from the muzzle.


This particular load is very accurate at 100 yards, producing consistent sub 3/8 MOA groups all day long, BUT.... I was never too excted about the extreme spread over the chrono, and since I was only shooting 100 yards at the time, it didnt matter too much.

Now i have been trying to tighten up the ES which is around 46 fps so I tried different seating depths and loaded 4 sets of different seating depths, .020 jump, .030, .040, and a .050 jump. The velocity did increase a bit and at both .040 and .050 the ES decreased to 36 fps... still not good enough, AND the accuracy decreased to about 5/8 MOA

I also tried CCI BR2 primers, they gave me a slight boost in velocity but no change in ES.

I think I am doing everything right, this is getting frusterating.

I was looking at Aliants new Power Pro powders, namely the 2000MR, supposed to give a nice fps increase to the .308 win and maintain safe pressures.


Any help is greatly appreciated.

 

[camac]

First of all you are doing nothing wrong. but as you get further and further into improving ES it just gets down to the fine details.
First thing to look at is the chargemaster - +/-0.1 grains is normal and someone reported a 0.25 grain spread on this forum. 0.25 grain spread in 308 will result in a velocity range of around 15fps+.
(now remember ES is accumulative so it is the sum of all the little things.
Next, you say you uniformed the primer pockets, did you do the flasholes. Lapua runs from 78 to 81 thou normally which can also result in 10-15 fps.
Then I would look at seating depth and neck tension again. Going from 20-50 thou is not much in the scheme of things. Try a 10 thou Jam, 10 thou jump, and 90 jump in addition to what you have tried. If you are finding the accuracy is still in the 10-20 thou jump range, try some differnet neck tension as well.
My guess is accurate weighing, flasholes and 10 thou jam will bring you down a fair bit. From there you get into annealing etc.

 

[SOcalsurferx]

Thanks Camac!

When you are referring to the flashholes, are you talking about reaming them?

As far as playing with seating depths more, what type of increments should I be experimenting with and what size test batch, ie. how many rounds with each different seating depth?

Thanks!

 

[dreever]

Try this: switch primers to CCI 250's and back your powder charge back down to 43.0-43.5 grains with the Sierra 175's. Weigh every charge on a reliable scale (I use a Denver Instruments MXX123) personally I don't mess with the flash holes in Lapua brass you can make things worse I found out. Same goes for primer pockets. As far as brass prep goes I bump the shoulder every time and use a bushing neck die with a bushing that is .003 under the loaded round size. When you are seating your bullets sort by what they feel like. If you find some feeling tighter or looser when you seat the bullet that can change your velocity so use them for foulers or sightersI would bet this will get you under 20fps ES or even more. If you are single loading try .010 into the lands if not go with your max mag length and hope for the best. The Sierra's aren't that finiky.

Danny

 

[camac]

Basically I agree with Danny too. Many things affect ES and As I said remember they are all accumulative, occasionally you will get one that has the smallest flashole, lowest neck tension, lowest powder charge etc etc. all together and then have a real drop in velocity. The more you put through the chrony the higher the ES gets. What you see in small sample sizes may only be the spread due to a couple of factors, Take a larger sample and you will see the extreme combinations (and in my mind the definition of extreme spread)
I ream my flashholes with a tapered pin reamer and a depth stop made from a light fitting screw terminal and hard plastic tube (will try and get a photo for you. A tapered pin reamer does a better job of producing consistant round holes than a drill bit. Every time I do this, the ES drops significantly).
http://www.victornet.com/subdepartments/Taper-Pin-Reamers/2548.html go for a 5/0 for large flasholes.
Danny's comments are right. They can be messed up but if done properly really help. Buy a $10 reamer and try a few. It is one of the cheaper experimetns you will ever do in this game.

As far as seating depth increments go, Berger recommends 40 thou jumps to find the right ball park, then 10 thou to fine tune. I think it is more dependant on how much bullet you have in your neck. A 40 thou jump when you only have 100 thou in the neck will have a very significant effect on bullet tension and also the jump effect. If you have 3-400 thou in neck, it is a much smaller percentage. But for starters, try a jam (10 thou), small jump (10 thou) and then some seated 30-40 thou shorter than you have done already.

Remember the other golden rules when checking ES. Make sure you fire foulers first and then try and maintain a steady barrel temp between shots.
A friend from the range came over a last year with an ES of 125 + (12 shots like in our matches) asking for some help on getting ES down. I took him to the range with chrony and then got him to fire a few foulers (12 shots, one match) and then let everything cool down and tested 10 shots correctly at same barrel temp, the ES was actually under 20. Foulers and heating barrels will have a huge effect too.

If you are getting a different "feel" on seating you bullets, you need to change something. Anneal and clean the inside of your necks for starters. If they feel different something is wrong but as Danny said is a good indicator. I like using my cheap Lee challenger press for seating as it is lighter and has more feel and I have shortened the hand lever for less power, more feel (My rockchucker for FL sizing and other work).

Also I feel you should be wary of "straightening bullets". Fixing runout this way may help accuracy at 100-300 yards but variable neck tension will give bad ES and longer distance will suffer. If you have runout it can hurt ES too,. As Runout can put a little "jam" on the bullet in lead/throat and cause variable neck tension too - but runout needs to be fixed in the dies/ brass not after loading.

Another comment (and believe me I could go on all day sorry.) on Powder charge. To achieve low ES you need to get good consistant powder ignition and complete combustion. This is different for each barrel length, bullet, powder combination. You can try different charge weights and probably have a significant effect on ES but it may or may not be in your accuracy node. You could then try other powders/ primers etc. Generally speaking though, if you stick withy one of the tried and true recipes and work on brass, seating depth, neck tension, runout etc they tend to work.

 

[SOcalsurferx]

Thanks for the great responses.

When I do all my load development shooting I try and be as scientific as possible... sometimes I get carried away and change more than what I should... one change at a time!!!

I shoot at a climate controlled indoor range so the conditions are nearly perfect and though a 1 hour session I usually only shoot 20-25 rounds. allowing adequate time for the barrel to cool between shots when I record my data, examine brass for pressure signs, etc.

When I first went about the whole process of developing this particular load I started at the recommended .015" jump and found the velocity I wanted, my max pressure range, and some nice accuracy nodes. I played with seating depths ranging in at the lands to 50 thou off, always coming back to .020 off as it produces the best accuracy.

I thought about the previous comment re: the chargmaster scale so I brokedown and bought a "real" scale today... At least that will cancel out that variable so I can focus on other things.

As far as primer pocket uniforming, I have heard it is not really necessary with Lapua brassbut I do it anyways as it makes the pockets neat and does not seem to have any effect on the ES. I also picked up a Sinclair flash hole reamer to see how that changes the ES.
One thing at a time though. I guess I will keep plugging away at it.

Thanks, any other wisdon is welcome!

 

[jo191145]

Just keep in mind when changing anything your sweet spot of 44.7gns will usually change also.

 

[Forum Boss]

Is the ES of 46 with 5 shots or 10.

Suggestions:

1. If you have any untouched brass left, try loading a few without touching the flashholes. Most of the tools on the market cut a chamfer from the inside which is hard to keep consistent.

2. I see that you bought a "real scale". That may be helpful. But when using the Chargemaster, I always remove the pan from the unit after dispense, then place it back on the load sensor. Maybe 1 charge in 12 I'll find a difference up to 0.2 grains (usually high). I'll then re-throw that charge.

3. Try 0.010" off the lands-- that is where a friend's rifle likes to shoot Sierras.

4. Remove the expander ball (if it is still in your die) and try different neck tension. You didn't list the loaded round neck diameter, but a .336 bushing might be too loose if you have under .012 neck-wall thickness.

5. Before loading NEW Lapua brass run an expander mandrel down the necks.

 

[SOcalsurferx]

The ES of 46 is with a 10 shot string.

The brass that I shot that string with had untouched flash holes, just cleaned up and uniformed the primer pockets with the Sinclair tool. It will be very interesting to see what kind of accuracy I have been getting as far as charge weights thrown from the Chargemaster go. I too remove the pan from the Chargemaster after every throw, with the "straw" mod to the trickle tube, I get about 19/20 charges dead on the money according to the chargemaster scale.

I originally shot these slugs (175 SMK's) at 15 off the lands and after I found a good node, I played with the seating depths and loaded up sets of bullets in 5 thou increments starting at the lands up to 25 thou off and discovered that the accuracy at 20 off was the best. I recently took them out as far as 50 off and the ES tightened up, but the accuracy suffered slightly. I will take them furthernext time.

I am running Redding comp. micrometer dies with just the bushing in the sizing die, no mandrel or ball. I have found though, that after I run the spent brass through a universal de capper and tumble them, that running it through a light expander mandrel to uniform the necks and take out any bumps or anything, produced more concentric cases after running them through the sizing bushing.

With the .336 neck bushing there is quite a bit of neck tension, Im not exactly sure but I believe they are running at approx 2 thou of neck tension, so I measured a loaded case at .338, and use a .336 bushing, I will definately play around with this as I have a .335 and .337 as well.

Thanks much!!!!!!

 

[Kenny474]

I would try some H4895. My .308 produces good ES/SD with it, and accuracy is good as well. I had tried Varget, but H4895 produced better accuracy from the small test batches I made.

 

[SOcalsurferx]

I really appreciate all this advice. My first time doing any real precision loading and I am learning every day. I will make some adjustments and report back!