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SD/ES Problems

bozo699

Gold $$ Contributor
Hey Fella's
I have been working up loads for my new F-class 6.5*284 factory savage.
I have tried the usual, Lapua cases H 4350-H4831-H4831sc-v-165-RL22. 210m-215m br-2. I have exactly 100 down the pipe.Group size isn't great 1/2-3/4" but I am more worried about SD/ES ,one group of three will be in single digit so will load three more,totally unacceptable,double digit #s. there are more double than single digit groups, I don't get it,What am I doing wrong? Barrel is cleaning easy,neck tension is .002 ,no neck turn,all other case prep is done,weighing every load down to the kernal,seating the 140 bergers,139 lapuas to the lands just touching,new pact chrono backed up w/new chrony chrono,readings respectfully the same.I want to use this new rig for 600 and 1000 yd work need low sd/es.Any advice or help would be greatly appreciated.

Wayne.
 
Hi Wayne,

This thread may be of some interest to you. It doesn't answer your query directly but maybe some food for thought if applicable to your situation.

http://www.accurateshooter.com/forum/index.php/topic,3748627.0.html
 
Wayne, while a lot of guys use bullets seated just touching or just off, I am not a big fan of that system. The problem is bullets vary a bit in size and shape. Not a lot, but if you are only touching by a thou or two some bullets that may be more tapered or slightly fatter will be touching with more pressure or not at all. And even if you are jamming .005, bullet variance will still change things a bit.

I only run .001" neck tension and seat bullets way out so the rifling actually seats the bullet. That way they are being seated consistently regardless of minor differences. They will all have very close to the same amount of pressure pushing them into the lands, and should release very consistently. I usually have decent ES/SD and I am no loading magician by any means, and I use a Lee powder measure and scale, so I must be doing something right.

Personally, I think either seat jammed or at least .005 off, as that gives a bit more leeway to bullet variance.

I also did a little experimenting a while ago as well. I seated bullets with .001, .002 and .003 neck tension in Lapua .222 brass (reformed .223, light turning) 1x fired. I then pulled the bullets very carefully and measured the neck ID. Wouldn't you know, they were all the same. That tells me that anything over .001 and the bullet is just expanding the neck, and bullets make for poor expanders.

I had read this in Modern Reloading and wanted to see for myself. And what I saw was exactly what was written. Now if I had a strain gauge and could measure the difference in bullet release force, I would have some really good data.

I hope you find a solution, as I want to see you enjoy that rifle and not fight with it!
Kenny
 
Thanks ,6br,Kenny
I have read those posts before I did pick up a little more tonight by rereading,Thanks again fella's I will try again tomorrow.The new Lapua brass is all fire formed now and I might do a little better with your suguestions.Thanks.
Wayne.
 
try some of the wolf large rifle primers. i have found that in my .223 rem and my 6BR that since i switched over to the wolf, i have attained significantly smaller es/sd than any other primer i have used to date. went from using cci br-4s to strictly wolf.
 
Wayne, the main thing to be aware of is that an SD from three shots is really meaningless; you can't rely on that number. You need a far larger number of shots to get a reliable SD number, at least ten shots and twenty would be better.

This might be useful to you:

http://riflemansjournal.blogspot.com/2010/02/reloading-velocity-decisions.html

And this for further study:

http://riflemansjournal.blogspot.com/2010/07/statistics-for-rifle-shooters.html
 
When testing worked-up loads, I fire 10 shot groups of each load. When I find one that shoots accurately, I'll then load 20 of that load, and test again.

I agree with German that 3 shot groups are statistically meaningless, 10 shots over a chrono will give you some valid information upon which to proceed.

Bill
 
What Kenny said is very interesting, with my 6.5CM I'm was on the road to trying that very idea - after neck turning my Lapua .22-250 brass to a loaded .289" neck the neck tension is very light so I'm loading them jammed about .010" so the rifling will actually be setting the bullet back to its final depth. Of course that gives you an issue if you need to pull that cartridge out before firing, that's not a new issue though.

I've been having a hard time getting my 6.5CM to get low ES/SD with R17 so I'm looking into slowing it all down with a different powder now - after all, I don't really need a 140 running over 3000 FPS. I'm going to have to give these articles posted by 6BR and German a good looking over, I'm always looking for ways to load better and new insight is always a good thing. I wish getting single digit ES/SD with the 6.5CM was as easy as it is for .223 and 6.5 Grendel - I can do it with those two without trying.

Wayne (two Waynes in this thread)
 
This topic is a good one and once again I believe it should be stickied. Controlling velocity spread is one of the main issues facing all long distance shooters. If you don't control it, you are not competitive.
I feel I could write a book on this topic but I don't think everything I say would be 100% correct so forgive me for any errors - I don't claim to be an expert but will post some of my observations.
I went through your exact pain Bozo with exactly the same rig a savage F class 6.5* 284 (after shooting 308 all my life) Read the other threads and articles again and again. Remember ES is a sum of all the little things. German is right you need large samples to get an accurate picture. For a 6.5*284 large samples mean barrel life though. For the 6.5*284 I recommend you do as much as you can with brass before trialling too much more for this reason.
As you are weighing to the kernel (+/- 0.02grains or better accuracy a +/-0.1 scale will not do this) then for me two other significant effects on ES are neck tension and primers (plus barrel temperature). Each of these you could write a book on (especially neck tension).
With Primers - Lapua brass tends to have a variation of around 3-4 thou in flashhole size. I uniform mine to 81 thou with a tapered pin reamer and depth stop 5/0 is a good size - a 5/64 drill is 78thou (bit small), 2mm is 79 (ok but still a little small) and # 46 wire drill is 81 thou (good size) - ditch any that are too big). This will tighten ES up a bit. Uniforming primer pocket is also recommended but I found with Lapua it didn't make any significant impact as long as your primer seating feels very uniform and they seat to a uniform depth as Lapua brass tends to do. Ditch them when they get loose.
I use CCIBR2 but believe Wolf will get very good results as recommended above.

Now neck tension: - wow what a curly one. Neck tension is affected by many things, neck diameter, springiness of brass (annealed vs much fired), seating depth, and really you should consider the position regarding lands as well as this effects initiation pressure too. Also runout can significantly effect neck tension as well as bullet straightening, neck thickness uniformity etc etc
Wow - so what do you do with this - Savage tends to have a lot of freebore (mine did). What this means for neck tension is as you chase the lands, you significantly reduce neck tension (losing on one hand and gaining on the other). Remember a bullet seated .100 inch has 1/3rd the neck tension of one with 0.300 -(try it in a hammer type bullet puller - one will slip out easily. the other takes a lot o whacking). I would go with 1-2 thou "neck tension"and try and load as straight as you can and trial different seating depths. Go with the Berger recommendation and start slightly jammed then increase by 40 thou at a time (up to 150/160 or so). If you do small sample sizes to save on barrel life make sure you further test your final load with a full set fired under real F class conditions so you know what you are up for in the record shooting - expect a significant jump in ES.

Single digits on a 10 + shot sample is the holy grail and very hard to acheive. Be happy if you get you ES into the teens for now. That is a good effort and will have you shooting decent 1000 yard scores.

After the three things above you can start experimenting with bullet runout, annealing and neck turning for a few extra points.

***Note barrel temp and fouling has a large effect on velocity. Shoot with a fouled barrel and try and keep barrel temperature same for shot to shot - I actually decrease my load slightly through my firing string as I always find a climb in velocity. My Shot to shot spread is good - nearly always single digit. But from number 1 to 18 (15 shot match with 3 sighters) can be large gain in velocity but each barrel is different. The savage barrel was the worst for this - mine climbed over 100fps from shot 1-18 but by staggering the load and all the above I could keep it in the teens.
 
Another tip Wayne - I see you have listed three powders, 2 primers and 2 bullets. The combinations of these are too many. Take a tip from Jason on the main 6.5*284 page. Pick one primer, powder and bullet combo. Work up a load on this unless it proves incompatable. There are many good ones but the most common I have found here is SMK 142 with Lapua brass. Then either fed or cci primers (but wolf are good too - just pick one and stick with it) and either 4831sc(ADI 2213) or 4350(2209). These are tried and proven 1000's of times over. Personally I had difficulty with my savage barrel and the larger bullets (not on velocity spread but group size) and settled back to the 123 Lapuas. These work well out to 1000 yards and if you believe the quoted ballistics give up nothing (at 3150fps to the 142 SMKs (at 2950) all the way out. Personally I believe the Sierra ramped figures more than the quoted Lapua but needless to say they are close enough to make no difference in the real world. My group size dropped significantly and scores rose accordingly after I changed to 123 and got the ES under control. The newer (non savage) barrels handle the 142's no trouble at all - I may have just been dealt a funny one.
 
In regard to neck tension I was attacking the issue with trying to go lighter figuring if I was given a say a 20% variance with neck tension from whatever cause, that if I had a given amount of tension, say a 10 pound 'drag' 20% would be 2 pounds but if I cut that tension down to 3 pounds we're only talking about a variation of 6/10 of a pound.

I lowered my tension by neck turning (.289" loaded), and I also put about the thickness of a nickel, .075", between the shell holder and my full length sizing die. Only about 1/2 of my neck actually gets sized, the other half stays the same diameter of the fire formed neck of my chamber giving it more of a tight fit and keeps it more squared and center in the chamber.

Maybe this is a poor man's way of doing things and I'm totally crazy doing it?

Wayne
 
15 tango - Wayne. Do you bump your shoulder after fl sizing this way? I have always found headspace growth by doing this and German wrote a recent article on it.

Whilst it is an interesting thought, the question is are you getting enough powder ignition initiation pressure? The idea of a factory crimp or getting near to /jamming the lands is to help a good and consistent powder ignition. Whilst light neck tension is good for runout, increased neck tension helps initiation here too. Ideally 1 thou neck tension for runout but seated fairly deep into the neck seems to work well for consistent powder ignition. Going for more neck tension (by decreasing diameter) indeed can increase runout and with a diminishing return on neck tension as pointed out above.

In my humble opinion because the 6.5 * 284 has a short neck you really have to have the reamer set correctly for a good amount of bullet in neck as well as being near the lands and have good entry into the lands to have good initiation consistency. Dave Kiff really does an exellent job of doing that with his reamers whilst staying away from the donut (which also dramatically effects neck tension). I think the long throated savages are therefore harder to tune for the heavier bullets (but may be incorrect in my thinking here). I have just rechambered my old savage with my PT&G reamer so may get to testing whether the PT&G reamer improves the way this barrel shoots the heavier bullets over the next few weeks.
Cam
 
Cam,

With Hornady brass I had to bump my shoulder back every 5 or 6 loadings or the bolt would get hard to close. I haven't ran my Lapua brass enough yet to see if or how many times I can fire it before i need to set the shoulder back again, I'm sure I will though.

Wayne
 
Wayne, the article Cam referred to is here:
http://riflemansjournal.blogspot.com/2010/06/basics-resizing-case-dimension-changes.html

You might find it worthwhile. I certainly agree that limiting the powder, primer, bullet choices is a good idea with that cartridge.
 
German,

Your points about what you called partial full-length sizing make sense to me as it's basically what I was doing. Wouldn't neck sizing only with a neck sizing die create the same problem (lug and lug seats damage) with the headspace not being properly set back to an original SAAMI spec.?

It seems that so many shooters neck size only and I wonder at what point does the possible wear on the lugs and seats become unavoidable, or just part of the game.

Thanks for the insight,

Wayne
 
Wayne, you're correct that neck sizing only can cause the same damage and that's a good reason to avoid either of those practices.

However, resizing back to SAAMI minimum is tougher on brass than you need to be, especially if the chamber is somewhere between minimum and maximum, as most are. As long as you're consistently sizing 0.001" to 0.002" below your fired dimension, then you're sizing enough to avoid lug damage and not so much as to excessively reduce brass life.

With properly sized brass and properly lubed lugs, you will never wear the lugs or lug seats enough to worry. I have rifles that have had well over 50,000 rounds fired (many barrels) and they are in fine shape.
 
Hey fella's,
I stayed up late last night and read through some of the material you so graciously supplied for me.I had a lot better day @ the range today. I am to tired to thank you or explain properly. but I will tomorrow thank you all very much!!
Wayne. :) :)
 
bozo699 said:
Hey fella's,
I stayed up late last night and read through some of the material you so graciously supplied for me.I had a lot better day @ the range today. I am to tired to thank you or explain properly. but I will tomorrow thank you all very much!!
Wayne. :) :)

I would like to repeat this and think we should all thank German for his work and effort. No doubt his articles, experience and comments have helped a lot of shooters.

Just a further comment I would make - German is spot on and I will firstly echo his comments. The outcome you want to achieve is a shell that fits neatly into the chamber (but is not tight and requires no effort to close or open the bolt). Ideally 1 thou under chamber size (0.5 thou clearance everywhere). 2 thou is quite good and acceptable (as German said).

In high power, or when pushing pressures, it is advisable to FL resize completely every time and set your FL sizer up with correct headspace.

However, A lot of people do use low pressure loads and neck sizing only. They need to bump their shoulders every 5-10 shots. The outcome is the same, they have a shell that closely fits the chamber but is not tight for easy bolt closing. Not so much in long range but certainly benchrest and other. This results in minimal brass movement and very long brass life. (especially combined with neckl annealing.

Neck sizing does not increase the headspace (measurably) - but if it is increasing during firing and neck sizing it is expanding during the firing cycle. It also increases when partial FL sizing. The reason is the brass on the body is squeezed in a little. This can only move in 2 directions. Towards the base and shoulder. As the brass is thicker at the base it moves less during firing and resizing so shoulder is squeezed forward. Neck sizing causes the brass to accumulate forward of the shoulder in the donut area (which is another problem altogether) and very slight increase in oal but no measurable effect on headspace.

I would suggest Wayne (15 Tango) that the partial FL sizing and loads you are doing is moving the brass of body very little if you are getting 5 shots out before bumping the shoulder and a lot of people would be happy with doing it this way. Similarly a lot of people neck size only when they use light loads. Shoulder bumping every 5- 10 shots.

However, I agree with German - Nothing beats a FL sizer matched very closely to your chamber - for brass life (without donuts), action life, accuracy and runout. Build one with 1 thou neck tension and if you want to experiment with neck tension from there, squeezing in another 1 thou at a time with a neck bushing die will still give you very low runout.

Cam
 
Update _ fired my first test target with newly chambered savage barrel (shorter throat and Dave Kiff Reamer). Big improvement. 300m group under 0.5moa with <0.3 vertical and 142SMK's. ES was good although only 5 shots was 17 fps. 1 thou neck tension and bullet seated right down into donut area with 10 thou jump (but donuts removed). The old long throat chamber best groups showed 0.5moa vertical with much testing. I could get ES down but not group size on old chamber. I am happy as have not redone load development or experimented with seating depth yet and barrel has over 800 rounds and was never a screamer. - I probably won't go further though as will use this barrel as hunting repeater with 130 bergers.
 
"Group size isn't great 1/2-3/4" but I am more worried about SD/ES."

Seriously, in F Class, until you get your loads CONSISTENTLY grouping 3/8" or less at 200 yards in virtual no wind conditions, you will not be a top contender at either 600y or 1000y F Class. When you have achieved that goal, you will have resolved whatever your SD/ES issues are.

SD, for some reason, is widely trumpeted in shooting circles, but is of no value to you, as a shooter or to your circle of shooting friends except as an "indicator" of CONFIDENCE that subsequent shots of the same load would,if plotted on a bell curve, follow the same pattern.

ES, the highest and lowest velocities, are Great for estimating the highest and lowest impact points for any distance. You want, of course ,to minimize the spread. Therein often lies the real work, when, shot for shot your recorded ES numbers strangely are in the single digits, but your group size looks like double ought buck shot, with your fastest shots impacting low and your slowest shots impacting high and the others going wide.

Diddling with the load is not going to help anything if you are already in single digits ES.
Go to work...mechanically... tweaking on those single digit loads to reduce group size. How you are holding the rifle, your front back rests, your bedding, etc.....try a barrel tuner.

Frank
 

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