partal full lenght sizeing accuracy issue

[riverratt]

Okay so i took y'alls advice and got a set of hornady headspace gauges for my 06. I found that my die was bumping the shoulder back just a hair under .009" i set my die to only bump it back .002".

After loading 10 rounds of my usual charge (probably should have started at min. Charge) I went out to test them. The results were, well not as i expected. My groups opened up nearly a 1/4" at 100yrd sooo i shot 10 of my old loads and they confermed this. The only major thing i noticed was that my old load seemed to be a tighter main group with fliers( one of witch was an inch out) where as my new loads were all located within a circular group.

Now that brings me to my question, to tighten up that group where would y'all start. I was thinking about playing with the powder charge first but that charge was the most accuret charge that i found. So, anyone have any other sugestions (ie seating depth, or playing with the sholder more).

FYI i am already seating my bullet aprox. .005 from the riffling

[tangolima]

0.25 MOA difference is pretty much academic, at least to me. 0.009" head clearance will surely shorten brass life.

You may vary the charge in 1% steps to see whether you can gain the difference back. But I wouldn't bother.

-TL

[Colorado Redneck]

Not knowing how much work you have invested in finding an accurate round, it is tough to suggest specific things to work on. I had a .204 Ruger in a 700 Rem SPS varmint. I tried almost all of the various bullets in .204 caliber. Used several different powders. It liked one combination. Just that one specific load was acceptably accurate. So you may have quite a few options to experiment with.

Distance off the lands is another topic that is not an absolute. Some rifles are most accurate seated touching the lands. Some are most accurate seated off the lands as much as 5/100ths inch or more. I have read sermons on the idea that the only means of achieving accuracy is seated touching the lands. From my experience that is BS. It takes trying various combinations to find what works best in any rifle.

Hope you enjoy shooting. Working up accurate loads is addictive, and sometimes the chase is more entertaining than actually getting that satisfactory load.

[stubbicatt]

From my experience, limiting shoulder setback will not affect your accuracy, but doing it properly will extend your brass life.

As you have learned, there are many factors involved in achieving gilded edged accuracy. Among the factors are:

1. Rifle capable of accuracy. Trued action, quality barrel, minimum chamber dimensions, CLEANED properly, adequate optics.
2. Proper method of holding the rifle and good shooting technique, whether slung or rested by whatever means.
3. Great ability to read wind conditions.
4. Good quality ammunition:
a. Quality bullet. Some bullets are more length tolerant than others.
b. Properly annealed brass.
c. Quality brass, properly prepared, including uniform necks, primer pockets, flash holes, and uniform volume.
d. Concentric cartridge cases sized to fit your chamber properly.
e. Suitable powder type and consistent powder charge. I weigh my accuracy powder charges, each one.
f. Suitable primers, hand seated to uniform compression.
g. Bullets seated to the proper depth, consistently.

A person can spend a small fortune acquiring the tools necessary to properly perform these tasks and measure the consistency of his ammunition. I have observed many otherwise normal people become extremely OCD and easily agitated in their pursuit of these goals, if after having a particularly good day when all comes together just right, they shoot a stellar group. They reason, improperly in my view, that if the rifle would do that once, it will do that all the time. A given rifle will have fluke groups, which nobody can explain, both on the good end, and on the poor end of the spectrum.

So I leave you with my thought that if you take these issues in turn, and work on incrementally improving each of these areas of focus, you will see a steady improvement in the performance of the man/rifle combo you have chosen.

[F. Guffey]

Okay so i took y'alls advice and got a set of hornady headspace gauges for my 06. I found that my die was bumping the shoulder back just a hair under .009" i set my die to only bump it back .002".

If that was the case I was misunderstood, I said you do not need all that equipment. I said all those gages are nice, not necessary just nice. I suggested if you purchases the gages learn to use them, learn to use them as standards and transfers, it is OK to covet them to an extent but learn to use them.

You could have made a comparator, if you have a comparator you could have determined the difference in length between a fired and full length sized/minimum length case from the shoulder to the head of the case.

Bump? I believe .009" would be closer to wreck than bump.

F. Guffey

[green_MTman]

.005 is very close to the rifling most people find .010 is most accurate

you may want to try magnum primers in the 06 this gives more reliable ignition and from what you said your previous load had to many flyers.

winchester large rifle magnum works well in 30-06 and its children.the Fed 215 mag's generaly work best in the H&H family but you may want to try those if the win primers dont work out

[AllenJ]

By changing the amount you size the case you have changed the internal capacity just a little, and add the case is only traveling about 2/1000 rather than 9/1000 before it sizes to the chamber when fired. I would think that those things could mean the pressure curve has changed and that the barrel harmonics are now different. I guess to answer your question I would start by doing a completely new load workup.

[Brian Pfleuger]

What you're doing there isn't "partial" full length sizing, it's PROPER full length sizing.

My first guess is that 0.005 off the rifling is causing some (or most) of your issues. That's so close that minor differences in pressure on the handle during seating and/or minor variations in the bullet mean that some are touching the rifling and some aren't. Plus, even just a .002 variance in a 0.005 intended jump is a 40% difference.

I suggest either getting into the rifling by about 0.005 to ensure that all bullets are touching (requires new load work up), or backing off to at least 0.01 so none of them are touching.

[Bart B.]

Setting fired case shoulders back .002" is perfect. Any more and accuracy tends go get worse as cases will stretch more between shoulder and head when fired. They won't stretch equally all the way around and that tends to make case heads out of square. Such cases won't shoot as accurate as those with square heads.

I see no need to do a lot of case prep. Federal, Hornady and Black Hills match ammo's cases are not prepped and it'll shoot 1/4 MOA all day long from a good rifle by a good shooter. And in SAAMI size chambers at the large end of their specs. I suggest you forget all that case prep until you shoot your stuff no worse than 1/4 inch at 100 yards.

With decent tools properly set up and used, anyone can assemble equally accurate ammo with new cases (or properly full length sized ones)y with the right primer (standard, not magnum!!) and bullet, metering extruded (never ball) powder charges to a 3/10ths grain spread. It helps if your bullets are a few ten-thousandths bigger than the barrel's groove diameter. Sierra's bullets tend to shoot best when against the lands; Bergers do best a few to several thousandths off them.

There's several proven loads for the .30-06 that are very accurate across many rifles. If one of them doesn't work in a given rifle, it's usually not the ammo's fault. It's my experience that two loads with a one grain difference in their average charge weights has little or no difference in their accuracy.

A 1/4 inch increase in groups at 100 yards may be normal; I don't know what size group it's being compared to. One thing for sure, if all your test groups with a given load are not within 10% of being the same size, you're not shooting enough shots per group for them to represent what your rifle and ammo plus you have to reflect the system's accuracy. You'll be better off shooting one 20-shot group instead of four 5-shot ones.

With factory barrels, with all their variables, they'll shoot all sorts of ammo into a few small 3- or 5- shot groups, several into average groups and a few into large ones. Which ones best represent the accuracy you can count on all the time?

[F. Guffey]

I found that my die was bumping the shoulder back just a hair under .009"

We have a lot or work to do 'here'. You were firing minimum length/full length sized casers in a chamber that is no-go gage length? And, you were happy with the results/accuracy..

From my experience, limiting shoulder setback will not affect your accuracy, but doing it properly will extend your brass life.

I agree with stubbicatt, first thing first. I need to know what rifle you are using. I have a lot of rifles with 30/06 chambers, if I want another one all I have to do is add the barrel.

F. Guffey

[243winxb]

Add 1/2 gr powder and set COL longer by .005" Moving the shoulder forward gave the case more volume. At the same time, it moved the bullet away from the lands.

[Bart B.]

Regarding a barrels' harmonics versus any component change . . . .

As the barrel has the same size and shape regardless of the component variables, it'll have the same resonant frequency and harmonic multiples thereof for every shot fired. A barrel's frequencies are 100% repeatable from shot to shot. Except for lever action ones with tubular under-barrel magazines.

Changes to the components will sometimes change the pressure curve and where in the barrel's whip cycle the bullet leaves. Heavier loads makie the amount of barrel whip and wiggle get larger before the bullet exits.

[F. Guffey]

riverratt, your improvement in sizing technique should cause the bullet to get out of the barrel sooner.

F. Guffey

[Clark]

I have got groups, that is plural, of less than 0.5" at 100 meters with 257 Roberts Ackley Improved with partial FL sizing.

That works good enough for me, but it is not going to fly when I have a number of rifles in the same cartridge. I can't keep straight what brass was fired in what rifle, let alone which brass is TO BE FIRED in what rifle.

So these days I always try to follow Bart's posts from way back when and push back the shoulder 0.001 - 0.002". I am not going to get his accuracy, but at least it will fit in the rifle.

[Bart B.]

I think "playing" with shoulder setback is a waste of time. I've seen no difference in accuracy with cases having .003"+ spread on headspace as long as the 30 caliber rounds are straight; no more than .003" bullet tip runout. That commercial match ammo I mentioned earlier has that much difference. Keep the average setback at .002". There's going to be a small spread unless you use a Redding competition shellholder whose height's enough to size fired cases just enough for .002" shoulder setback when it stops hard against the bottom of the die at the top of the press' ram stroke.

One other thing. If you're using a standard full length die, deprime the fired cases before cleaning then sizing them using another die fired cases easily fit in. Then adjust the expander ball height in the sizing die to start into the sized case neck when the case is pulled about 1/16 inch out of the die. This usually makes for straighter case necks on the cases. Bullets seated in straight necks shoot more accurate.

[tangolima]

Or use no expander ball at all. That requires special die, a bushing die or a honed FL die and neck turning of the brass.

-TL

[Bart B.]

Don't need to turn/uniform case necks when die necks are enlarged. Only if their neck wall thickness varies more than .001 inch.

[tangolima]

0.003" easily. I can only afford cheap brass, so I always turn necks.

-TL

[Clark]

I have turned necks and got more runout than before I started, but at least they weren't too thick anymore.

[riverratt]

Sorry for the late reply i left my phone at work last night. Anyway thanks for the responses. F guffy my rifle is a stock win m 70 my grandpaw got as my graguation pressent 12 years ago. I had a load for sierra 180gr rn that would keep a group under3/4" at 100yrd. Then i moved into indiana where i couldnt use my 06 for deer so iput the dies in the basement untill i got my reloading bench set back up. The basement flooded and all was lost

After i moved back over to kentucky i got an rcbs die for my 06 but with the shortage i couldnt find my regular bullets plus i got a new place to hunt with much longer shots so i called sierra and the tech toled me the bullet i was useing wasnt going to work over 250yrd because it looses to much velocity. They toled me that the bullet i needed was the 165gr bthp gameking.

After getting the bullets i started working up loads with imr 4064, imr 4350 and h4350. Best group was 57gr imr 4350. I then started playing with seating depth and got the groups around 1 1/4" with flyers out to around 2". So am i happy with them heck no, but it will kill a deer.

I now have time to work on my load before deer season so thats what im doing. By the way nice to have and have to have tends to go hand in hand with me

Bart i didnt know that about the expander ill check that in the morn when i get home. As far as my groups my grandpaw always said to dismiss the flyers as they are your fault not the ammo or guns. I have found that out to be bs but only recently. By correcting the headspace it seems that all my shots were in a circle so that could be a group whereas the previous groups had a small group with flyers so that was probably an anomally.

[1stmar]

I agree with Brian , .005 off the lands may not be optimum. You will get variations in searing depth where some bullets may be touching the lands and some may not be either .010 into our away from is a better metric.
As others have said, unless you were consistently getting 1/4 groups and now they are dble that, I don't think there is a statistical difference.

[Colorado Redneck]

Flyers may or may not be the shooter. Again, I had a rifle that would shoot tight groups with one particular bullet, except about 1 in 4 rounds was a flyer. Kept thinking it was me. But other loads using different brand bullets didn't have flyers. That one bullet seemed to not stabilize in my gun.

[McShooty]

I am kind of hung up on the idea of determining a difference of 1/4 MOA in the group sizes of two loads by firing ten rounds of each load. Was that two five shot groups of each?

[Bart B.]

Clark sez:

I have turned necks and got more runout than before I started, but at least they weren't too thick anymore.

That happens a lot. Especially with dies having minimum neck diameter and maximum expander ball diameter. Thinner neck walls bend easier than thick ones.

[F. Guffey]

So these days I always try to follow Bart's posts from way back when and push back the shoulder 0.001 - 0.002". I am not going to get his accuracy, but at least it will fit in the rifle.

Following Bart B.'s advise is not easy, he started out recommending bench rester methods, as in something they discovered a long time ago and that was full length sizing, that has not changed but the instructions have bee modified to reads something like "Do like the bench rester, full length size by moving the shoulder back .001" to .002" ".

I will stick with the original 'set the shoulder back .002" with the companion tool to the press, the feeler gage.

F. Guffey