WHY is my first shot high?

[docsleepy]

1. I'm loading very close to the lands, which increases the pressure. I'm using a 22" barrel - shorter than what most loading books use. Sierra lists max velocity with Varget, 120grain bullet as 3000; Hodgdon lists 3117 fps. Likely by 42.0 grains I am at max pressure and the loads above this should be avoided if possible. (Note I did see progressive flattening of Winchester LR primers)

2. Given the higher tempperature, the 41.6 load of today's data probably compares to the 41.2 gr of previous data (and note their vertical position is similar). Possible accuracy loading for summer might be 41.6, for winter 42.0 or slightly more. What do others think?

3. The geometric centers above 42.0 grains just make a circle -- probably because they are all statistically "identical" (impossible to separate with only 3-4 shots per group.

4. Note for this test, today, at least, the graphite regimen didn't perform very well for reducing the first shot error. With very few tests, the grease so far seems slightly better. Interesting that the first shot was indeed slower, again.

5. Something about what happens when the case is JUST slighltly too long--does it hit an assymmetric junction between shoulder / neck / leade of the chamber and BEND the case? Best thing I can think of to explain the wild shots is that the bullet got started aimed slightly off center.... Any other theories?

 

[Andrew Leigh]

Hi doc,

Accepting that the barrel is possibly poor and will be replaced I would now agree with ngnrd, perhaps it would now be prudent to back off on load development as I believe that there are two major variables at play. The one is the barrel and the other is the handloads themselves. Lets remove the one major variable first, the barrel.

Clearly your results prove that inconsistencies in case prep results in large inconsistencies in POI. I think that there are anomalies in the handloads and that these probably exist in the case preperation. The cases may well be past their sell by date through overannealing / overworking. You also experienced case seperation and mentioned three rounds resulted in hard bolt closing yet another indication of inconsistent case preperation.

Why are you FL sizing and then neck sizing?

The target at 42.8gr. has only 2 shots on it, am I correct?

When you get the new barrel I would start with brand new unfired brass, this will give at least four reloads before any annealing needs to take place. I anneal after every 5th time the cases are fired, you seem to anneal each time you load?

 

[docsleepy]

Andrew -- thanks for your consistent attention

1. The target at 42.8 has 3 shots, but you wouldn't know it because the group has opened up so much! The 3rd shot is way over to the right, at the next group's left edge of bullseye. By this point, the velocities are WAY over what Sierra lists as their maximum velocity for max load.

2. I'm fascinated by the concept of "over" annealing. Annealing should return the metal to an initial state. Repetitively annealing should not be able to return the metal domains to any "pre" initial state. I have had zero failures of the annealed neck; no cracks, and certainly no blowouts. These cases are certainly past 10 reloads and may be approaching 20. The incipient head separations are occuring consistently about a cm from the head. (bright line on outside, noticeable "dip" when feeling with the bent paper clip on the inside surface)

3. Why both full length AND neck size? Because many believe that the expander plug in the FL sizer contributes greatly to poor concentricity, and that neck sizing reduces this. In my case, I believe it reduces neck tension somewhat (I say that because I can feel the resistance as the mandrel enters the neck, so it apparently expands the opening a bit) and hopefully brings them all to a more constant tension.

4. There were 3 cases that ended up "long" and were difficult to chamber, (required maybe 5 lbs force on bolt) but other than that, the velocities appear very tightly grouped, right? (I think the one velocity in the 3200's is probably an error either of the chrony or of my recording). On this die, about 5 degrees in the bushing will set the die .001" shorter (more) FL sizing, so I had turned it out by 10 deg (.002) -- that resulted in some too-long cases as I'm closer to the edge than I realized... Will move it back where it was.... I was trying to get even more case life by doing absolutely minimal sizing as many suggest bumping shoulder back only .001" I should order a headspace cavity to allow more accurate measuring....

5. Good news -- two boxes of new cases arrived in the mail just after I left for the range, so I have plenty of new cases for trials with the new barrel when it arrives.

6. I should do a comparison of annealing every reload versus annealing every 4th reload and see what is the difference! It certainly is a lot of work!

7. The velocities I reached are beyond those of either Sierra or Hogdgon max-pressure velocities, and at the top, the Winchester primer flattened across its entire diameter and the firing pin indentation began to have a raised edge where it forced metal around the firing pin. These have nothing to do with the CASE, but indicate I am well into metal-deformation pressures, right? The only time I have gone any farther into high-pressure land was with a 6PPC and stout brass -- I would expect the possibility of real primer cratering and or pieced primers within a few more steps, right? (I had a few pierced primers once in the 6PPC rifle)

 

[docsleepy]

The good news for me, in my estimation was the following:

The change in the (3- or 4-shot) group center is, in the region of 41.2-42.0 grains, moving only 0.25" for a change of 0.4 grains. That means that the variation in point-of-impact for a charge error of 0.1 grains (the accuracy of the Chargemaster) is now in the range of 0.06", which is inconsequential in hunting deer! The errors of the barrel (it appears to be a 1-MOA or slightly better at times $85 factory pencil barrel) appear now to dwarf the powder charge aspects.

Possibly adjusting the seating depth would bring about a further reduction in group size, if further improvement were warranted.

But the FIRST SHOT problem (2" with the graphite, maybe 1" with the grease in very small number of trials so far!) is a much bigger hunting problem, unless you have deer that will hold still while you fire a fouling shot!

 

[docsleepy]

Attempt to allow you to see the primers. Iphone will focus only so closely, and no more.

Note the nice rounded edges on the unfired primer (farthest left).
The 41.6 charge still has some remaining rounded edge.
By the time you get to the 42.8 charge, the rounding is gone, the primer is just about completely flattened, and you can see that it is filling out much of the beveled primer pocket entry area. This means (I think) that the metal in that area was impacted by sufficient pressure to allow plastic molding.

These are Winchester LR primers.

 

[docsleepy]

The entire group at once

 

[Andrew Leigh]

Andrew -- thanks for your consistent attention

2. I'm fascinated by the concept of "over" annealing. Annealing should return the metal to an initial state. Repetitively annealing should not be able to return the metal domains to any "pre" initial state. I have had zero failures of the annealed neck; no cracks, and certainly no blowouts. These cases are certainly past 10 reloads and may be approaching 20. The incipient head separations are occuring consistently about a cm from the head. (bright line on outside, noticeable "dip" when feeling with the bent paper clip on the inside surface)

You CAN over anneal. The three stages of the annealing process that proceed as the temperature of the material is increased are: recovery, recrystallization, and grain growth. The first stage is recovery, and it results in softening of the metal through removal of primarily linear defects called dislocations and the internal stresses they cause. Recovery occurs at the lower temperature stage of all annealing processes and before the appearance of new strain-free grains. The grain size and shape do not change. The second stage is recrystallization, where new strain-free grains nucleate and grow to replace those deformed by internal stresses. If annealing is allowed to continue once recrystallization has completed, then grain growth (the third stage) occurs. In grain growth, the microstructure starts to coarsen and may cause the metal to lose a substantial part of its original strength. This can however be regained with Hardening.(Wikipedia)

The problem is that you NEVER know how much to harden to get the case back to optimum but by limiting temperature and time you can keep the annealing process within an acceptable band. You are grossly overworking your brass by the sounds of it. Over annealing and then over processing to get it hard again.

3. Why both full length AND neck size? Because many believe that the expander plug in the FL sizer contributes greatly to poor concentricity, and that neck sizing reduces this. In my case, I believe it reduces neck tension somewhat (I say that because I can feel the resistance as the mandrel enters the neck, so it apparently expands the opening a bit) and hopefully brings them all to a more constant tension.

I have never had good results with neck sizing. I am not for one minute knocking the technique but just stating that I cannot get a consitent neck tension. I would recommend that you do the one or the other.

4. I should order a headspace cavity to allow more accurate measuring....

I would agree.

5. Good news -- two boxes of new cases arrived in the mail just after I left for the range, so I have plenty of new cases for trials with the new barrel when it arrives.

Do not anneal until at least after the fourth firing.

 

[docsleepy]

Hi Andrew!

We'll give it a whirl your way!

Thanks for the insights!
After yall's concerns, I just FL sized ONCE for the last two or three sets of tests. When annealing, I use a very dark room (only during nighttime) and don't start until I can recognize certain cans in the dark. Then I stop as soon as ANY discernible dark red glow is appreciable and dunk in water. Thus time/temperature is limited.

Certainly worth trying the new brass with much more limited annealing. It can then be compared with some of the many many timed used brass and I'll learn even more.

I'll probably hold off for now until the new barrel arrives, as I think I've learned the majority possible with the old barrel.

You didn't comment on the velocities or the primers?

 

[Andrew Leigh]

You are a very hot, as mentioned the Sierra sofware had the Varget load for the 120gr at a max of 43.8gr to give 3000fps. At 43.2gr you are close to 150fps hot, discounting the extra 0.6gr you are still about 100fps hotter. At 42gr. you should be under 2900fps and your are at 3100. This all for a 26" barrel, the fact that you have a 22" barrel make these loads even more scary, you can add about 120fps to existing loads to bring them back to a 26" barrel. Conversely you should be shooting 3000fps - 120fps at max load.

What is your jump to the lands, it seems like you are shooting off the lands creating undue pressure? Your OAL should be 2.780".

The primers at 42.4gr still look OK. Did you have any hard bolt opening problems?

 

[docsleepy]

Hi,

Yes, for these tests I SHORTENED the COAL by .010 to get it off the lands somewhat -- I was previously right on the lands. I do believe that I am way over pressure, which is probably why the velocities are beyond book value even for a longer barrel.

There were two or three "not perfectly easy" bolt openings, but nothing that required a 2x4. I was pretty convinced the highest and next highest loading were over pressure and that is one reason that I ddin't do the 4th shot at each.


What I've read before in 6PPC is that when you go overpressure, the groups will tend to blow out, and it seemed to me that I saw this in the next-highest pressure group.

The first three shots in the 41.6 group were a cloverleaf. Given the increase in temperature (80-85F) , these are probably comparable to the 42.0 set of my previous tests (at 60-70 F) -- and that set was the 0.5" group. Sure seemed that this particular pressure/velocity was optimum for that barrel -- would need to adjust the powder based on ambient temperature to achieve that group.


Did you see in the article someone referred to us that they stated that loading into the lands was an absolute requirement in all their experience to get the best accuracy? They were regularly achieving 0.030" groups, and considered 0.2" an utter failure.

 

[docsleepy]

y'all got me thinking about annealing. Found this temperature guide:

http://www.reloadersnest.com/forum/topic.asp?TOPIC_ID=20330

480 Barely red in the dark
600 Dark red
800 Cherry red
950 Orange, barely visible in sunlight
1100 Orange-yellow, visible in bright sunlight
1300 Light yellow, nearly blinding, welding goggles required.
1500 Nearly white, blinding

I use a dark room (one neon bulb night light behind my back, wait until I can see certain cans on a shelf in the dark) then stop as close to barely red-dark red as I can, which would be 480-600 from the above chart.

http://www.6mmbr.com/annealing.html
Is a helpful article on annealing, several lower down on the page seem to use the same technique (I bet it is where I got it front, I surely didn't think it up myself). There are some interesting statements in that article.

I'm very interested to see how this will go with much less annealing. Will surely be a lot less work on me! With my 6PPC/turned necks, I never annealed. When I first started working on the 7mm08 I noted continuously worsening groups....and then I tried annealing and suddenly the groups tightened up dramatically (shot a 10 shot group that astonished me that day). But perhaps I'm going too far.

 

[Andrew Leigh]

Did you see in the article someone referred to us that they stated that loading into the lands was an absolute requirement in all their experience to get the best accuracy? They were regularly achieving 0.030" groups, and considered 0.2" an utter failure.

No problems with loading into the lands, just make sure that load development starts well down the scale. Some bench guys seat long and so lightly that they actually "seat" the bullet into the lands when they chamber.

The rifles they speak of have substantially better actions and barrels than the off the shelf rifles, so for lesser mortal like me one hole groups remain the Holy Grail. The one guy they mentioned had such a close fitting action that re-inserting the bolt was a mission as the tolerances were so tight that one needed perfect alignment for the bolt to enter the action.

 

[docsleepy]

The results that I achieve around the 41.6 and 42.0 area are plenty good enough for my intended use (deer, up to 300 yards). The variation in average point of impact was less than 1/4" for 0.4 grain differences. I can use 41.6 for hot days, 42.0 or 42.2 for cold days.

Now the remaining problem would be the 1st (cold) shot error. In the remaining time prior to the new barrel, I may give some more tests of grease (a new tube arrived) versus graphite -- or maybe mix the two together?


Midway's email says the 7mm08 and 6PPC case gauges have shipped.

 

[balderclev]

I remember that there is something that welders use to control temperature when heating steel. If I remember correctly, it is rubbed on the steel and melts at a certain temperature. There are several variations of it that melt at different temperatures. Wonder if that might help in annealing.

 

[docsleepy]

http://www.nissenmarkers.com/catalog/Category/Temperature-Indicating-Sticks

Found them. Reasonably priced also. I may give this a try!

 

[Andrew Leigh]

Gunshops sell a product which you paint on and it indicate the temperature.

Tempilaq and Tempilstick

 

[BullfrogKen]

Forgive me, but if you're going through all this hassle for deer - loads for cold days, loads for warm days, annealing the literal life out of your brass, seating into the lands chasing after benchrest accuracy. . .

You're not paying attention to the right things. You've totally lost yourself in the weeds of extreme accuracy only necessary for benchrest matches when you don't need it. Especially at 300 yards.

Learn to judge range and dope wind. Or just buy a laser rangefinder and learn to dope wind.

 

[savanahsdad]

Gunshops sell a product which you paint on and it indicate the temperature.

Tempilaq and Tempilstick

yes, only 166 post to get through to get to the right way , it is TEMPILAQ TEMPERATURE INDICATOR , $21.99 per 8oz , in stock at midwayusa.com, right now. I use the 750 deg but I only use it on old cases like 32rem, or any thing I know to be 20+ years old, I have never done any of my 7mm-08's ,all of my 7mm-08 are Rem7-08 cases and are at 10+ loads , I get sub 1MOA with my Savage mod 16. in 7mm-08 new in 1997 it got 1.75MOA out of the box with factory ammo after I gave it a tune up and my hand loads added to the mix, it now shoots 1 to .75 MOA, some days a bit high and some days right on but the first 5 shots hit under 1" .I say as other have. stop annealing , brass that is too soft will losse it's grip ,

 

[docsleepy]

"You're not paying attention to the right things. You've totally lost yourself in the weeds of extreme accuracy only necessary for benchrest matches when you don't need it. Especially at 300 yards."

I think there's a lot to be said for this!
My major concern is the first shot error. 2 inches at 100 yards turns into 6 inches of 300 yards, and add a bit of new hunter anxiety, and you've got a deer that I missed.

The grease trick seemed to reduce the error on the first shot significantly

There seem to be a lot of misconceptions about annealing. Here's a quote from 6mmbr.com: "The smallest 1000-yard 5-shot group ever shot in IBS competition was done with brass annealed after every firing."

At least in my experience, annealing increases rather than decreases neck tension. You can certainly feel it when you pass the Lee mandrel into the sized brass. Certainly, this level of effort, it's probably overkill. But since some members felt like a optimum charge weight test was needed, best to be sure that the brass all has good neck tension. I learned this the hard way, early on with this rifle, that multiple times shot brass would begin to not even hold the bullet.

Sure wish this rifle would put five shots inside a quarter on the first five shots! It certainly can do that after the first couple. Still looking for ideas on what's wrong with that first shot. Any good ideas?

 

[docsleepy]

I did buy the laser rangefinder quite a while ago. Good purchase.

 

[docsleepy]

Great Progress!

Progress is being made!

This is today's cold-shot test (can only do ONE each range trip....). I went to a 300-yard range, measured the MOA of the various dots on my scope reticle by comparing to a known measure at 200 yards, adjusted my aim accordingly by the dots to account for a 2.5 MOA drop at 300 yards compared to my 1" high zero at 100 yards (see previous photos for 41.6 grains Varget) and let 'er rip!

Cold shot at 300 yards is well within a deer kill zone, 1.25" above bullseye! This was just about exactly the shot I missed last fall.

The 2.5 MOA drop estimation comes from entering in all the particulars into jbmballistics.com since I now have oodles of data on this bullet and this load thanks to all the OCW tests.

The barrel prep I used was the "grease patch" one: Over and over and over I ran a greased patch down the barrel (using a bore guide to protect the chamber), and finished by a clean patch only in the chamber.

I then proceeded to take out 4" clay pigeons (another proxy for deer kill zone) one after another on the same berm.

(The lower bullet hole in the target is my "cold shot" from a Rem 6.8SPC. )

This is huge for me. Thanks for all your advice, guys!

 

[Andrew Leigh]

Hi Doc,

as a matter of interest I went to the range yesterday to develope a 120gr. load for my 6.5mm. As a matter of course I always fire my fouling shots into the butt but given your experience I fired them on target just to see what the first "cold" shot did.

To my surprise I shot a three shot group of 0.39" on POA. The best goup I have EVER shot with a hunting rifle to that point. Oddly enough my first OCW load was at the same powder charge and the group opened to 1.5", just goes to show what shooter inconsistency does.

Another observation was that I was using S&B cases which I forgot were inconsistent and that the shoulder was not where I needed it to be. These I had put in a box to discard but it has been a while since so I forgot their fate, my bad. My Chrony results were awefull which I put down wholly to the brass. The std dev's went from 4.6 to 42.7.

I had specially bought Lapua brass for the exercise which I did not use. Note to self, chuck brass you want chucked immediately and crush the necks so you can't reload them and use decent brass.

Despite that the 6.5 was awesome, also picked up that the action screws are a little loose as I was getting horizontal stringing. Our winter are so dry that stocks "shrink" a little during this season and one must be mindful to tweak the screws.

Had two accuracy nodes which need to be varified when I load with better brass, the group of the day was 0.37" which at 100m (metric land) is 0.32MOA. I am super chuffed.

 

[docsleepy]

Who made the barrel? Pretty good rifle I would say!

Didn't you have a hunting trip recently? How didthat go?

 

[Andrew Leigh]

It is a CZ550 that I bought brand new.

I have a trip for the 26th June to the 2 July on my friends farm in the Eastern Cape and another one on the 29 to 21st August in the bushveld of the north. Will let you know how it goes.

 

[ottsixx]

cold clean barrel does it every time or it has for me anyway.