Load development forum...

[Idaho Sharpshooter]

Is there any real interest in a forum here based on identifying, and eliminating, the variables that keep rifles from attaining their best accuracy? Maybe just a stickie?

Simple things like punch-marking boolit molds, so that the boolit can be indexed from the time it drops gently from the mold, to loading and firing it.
Boolit boards, to allow you to place the boolits in order cast, etc.
Mirage Boards, and wind flags.

All that jazz...

Rich
Sua Sponte

[runfiverun]

rich.
you know there is.
there is a sub-header for cast boolit loads it might go best there?

[rhbrink]

Excellent idea!

RB

[Plinkster]

Wow, that's going deep. I'm in!

[Lefty SRH]

Don't know what I can offer to the forum cause I'm still learning myself. BUT, I sure like the idea.

[Idaho Sharpshooter]

Okay, as a start:

Let's say you have an accurate J-bullet word rifle in .308 Winchester.

1. Check your locking lugs to see how evenly they bear. Use Dykem Blue or Red and coat both lugs, front and rear. Work the bolt a couple times and pull it. There should be very little Dylem marking fluid left. If so, is it fairly even on both sides, and front and rear? I demonstrated this to a friend many years ago, and we found that his left locking lug had about 80% bearing surface, and the right did not touch. He laughed, and told me the factory set them up that way on purpose. It was a spare for backup.

2. Say you have a 2-cavity or more mold. Take a very small prick punch and punch a small mark in one of the cavities just ahead of the bearing surface. Cast your boolits with due care, and segregate those boolits. Those are your testers. Orient those boolits when you size/lube/seat the GC.

Hopefully you have a mold that fits the throat fairly well. Hopefully, you have honed out a sizing die so that the boolits are a slide fit in the die.

NOTE: everything you do to a nice cast boolit after you drop it gently on an old towel is bad for it!

That tiny punch mark allows you to place it in the sizer/lube die with the mark facing you. Every one!

At this point you have a hundred nice uniformly made, ready to load boolits.

You have twenty-five once-fired cases (from your rifle), neck sized only. You have measured your expander button in the neck sizing die, and it is .001" under boolit diameter. This is for consistent neck tension. Four for foulers, and twenty for record. In this case, four 5-shot groups.

Orient the boolit, punch mark facing you, and ease them into the seating die. They should all seat with the same easy amount of pressure on the press handle. If one feels a bit different, set it aside for the fouler.

The rifle: for this test, you are going to adjust the scope to print about an inch high and right of the aiming point. Shoot those nice BR-style targets with the 1/4" grid and 1" black square in the center. When you shoot your fouler, park it off the paper. Now, you have this nice clean target to start on. If you hold on the bottom left edge of the black square, you should be rewarded with a nice group in the middle of the box. This assumes you have a good load with this boolit, and want to shrink it significantly. If not, we will discuss the Ladder Method of load development.

Last, but not least, you need to make a mirage board. A foot square piece of plywood works great. Paint one entire side white. Then, mask one-inch lines across it from top to bottom, and paint the exposed paint portions black. It should look like a vertical Zebra. Drill a 1/4" hole centered on the top edge.

When you staple cardboard and a target to your frame, the mirage board goes at the top left or right side. You just need to be able to see it in the scope.

Mirage: I hate it. If you watch the mirage, it will begin to move upwards slowly, increase to a point where it begins to "boil", then breaks up. This is a never ending cycle. Just watch it thru a good spotting scope, if you have or have access to one. It will amaze you.

Four little things you can do to minimize the variables. If your rifle will shoot a load right at an inch; these things should shrink it by at least 1/4".

If you can find a couple boxes of the old nickle-plated Federal Match 308 Brass, it is very uniform. Ditto for Norma.

I followed the procedures listed above more than twenty years ago with my first Savage BV-12-SS, and more than 2200 rounds of the old Lyman 311284 later, it will still consistently shoot 5-shot groups under 1/2" at 100 yds.

I hope this has been of some benefit to you all.

regards,

Rich
Sua Sponte.

[Lefty SRH]

Nice post, already learned something. BUT I don't really get the Mirage board. Granted I'm not a bench shooter but there are several that frequent the public range in my area and I've never seen what you are describing nor have I ever heard it discussed. What is the mirage boards purpose?

[Idaho Sharpshooter]

Ever drive on blacktop on a hot day? Those shimmering waves that come off is serious mirage.

The board will show you exactly what the mirage is doing. If you are a serious bench rest shooter, you have likely had lessons from a more experienced BR shooter about how to read it.

My post assumes no BR background on the readers part. Mirage can displace the seen target by a caliber in some cases. It is a cycle, and once you spend some time learning to read it you will be able to compensate for it. If you go to the range on a nice sunny day over 80-degrees, you will have to contend with it.

I saw a target shot the year I went to the Super Shoot with "four in a bughole, and the fifth in a different zip code.". When you measure those four shots, and they go .043" and the fifth one opens it up to .643" the most common answer is mirage displacement. The other one is "I got caught in a switch.". That is a wind change, but with wind flags all over, it is a rare occurrence.

We'll talk about windflags, if you wish, some other time.

Rich
Sua Sponte

[Griz44mag]

Sounds interesting, but my Rem 700 will consistently place a one shot group into the width and height of a deer's heart, taking both lungs in the process, at 200 yards. Neither wind or mirage, heat or cold, rain or sun can change it. What more could anyone want?

[Pilgrim Sojourner]

Rich,
I am also very interested in your tips for “ultra accuracy.” Would you describe in detail what you do to ensure uniformity in your cast boolits—i.e. casting tips, cooling tips, aging the boolits, specific reloading tips, etc., etc.
Thanks.
Tim

[Idaho Sharpshooter]

My 6" Colt Anaconda in 45 LC will do that.

[Idaho Sharpshooter]

Pilgrim Sojourner,

One of the things I learned shooting in the CBA and Schuetzen goes waaaay back to H.M. Pope. He made some 60 hole blocks. He got his mold up to temperature, not easy with a plumbers furnace on a consistent basis, and began casting. After a dozen or so boolits, he began looking them over. He would drop the boolit from the mold on a folded cloth, refill the mold, and set it down. He picked the boolit using 6" tweezers and examined the boolit including the sprue cut. If it was smooth and round and filled out, he stood it up, base down, in block hole one. Then he repeated the process. He placed them in order cast. After a block full, he would refill the pot and let it come back up to temperature.

With our larger electric pots, we can hold temps much more uniformly, so I cast two blocks full.

I just stick them in the nice Dillon plastic 100rd 22 Hornet boxes and label the mold number, date cast, and alloy. I have not done any better with specific date aging, but some have. I do not size/lube/GC them until a day or two before I go shoot.

Punchmarking a cavity so you can orient it from block to loading is the best thing I have found for uniformity.

A Blackmon swaging press and a die that will "uniform" each boolit is a help. If you send him a few boolits that measure as close as you can get, sized but not lubed of GC'ed he will (or at least used to) make you a die that would uniform them to .0005" or less. The top shooters in the CBA do the same thing, but, since swaging the boolit is against the rules, they call it something else, "bumping" I think.

I have used a ball head tubing micrometer to measure case neck thickness uniformity, and worked two directions from the numbers. You can turn the casenecks to even thickness. That will cut waaay down on split casenecks if you only neck size.

If you want to go to the time consuming process of turning casenecks, be warned that it will not be of much help with factory chambers. SAAMI specs call for a minimum chamber dimension, and a maximum loaded round diameter so pressures do not rise over specs.
Turned casenecks just increase the chamber neck clearance on a loaded round in factory chambers. This is not good.

Bench Rest Rifles use custom minimum spec reamers, and turn casenecks to allow as little as .002" clearance on the neck of a loaded round. You can closely approach that by necking down longer brass and shortening it. Example: buy some good quality 30-06 brass, like a hundred pieces of Norma or RWS. Gently run it into an FL .308 Win die. Trim to .308W length.
What you have done is make the neck thicker, by using the thicker part of the brass on the shoulder and body. Instead of .006" to .008" clearance on the neck, you may have cut it to half that.

A concentricity gauge like the one RCBS makes allows you to gauge run out on a case, or a loaded round. Partially seating the boolit and then rotating the case in the die 180-degrees is another small thing that has cut run out from as much as .006" to the .002" range.

Uniforming primer pockets is very useful, at least for me.

hope this helps,

Rich
Sua Sponte

[Griz44mag]

Geez Idaho, don't be such a crusty old coot, lighten up a bit. Don't be tacky. That was supposed to make folks smile.

[Idaho Sharpshooter]

right back at ya kid!

No offense taken, none intended.

Post amended.

Rich
Sua Sponte

[alrighty]

Is there any real interest in a forum here based on identifying, and eliminating, the variables that keep rifles from attaining their best accuracy? Maybe just a stickie?

Simple things like punch-marking boolit molds, so that the boolit can be indexed from the time it drops gently from the mold, to loading and firing it.
Boolit boards, to allow you to place the boolits in order cast, etc.
Mirage Boards, and wind flags.

All that jazz...

Rich
Sua Sponte

I like the idea and Thank You Sir for taking the time to do this.This site has a wealth of knowledge for anyone that is willing to take the time and read due to the hard work of others like yourself.I just wish I had found this information out earlier in life.

[mainiac]

Rich,keep it going man!!! I myself am familar with all this ultra accuracy stuff,as well. Ive gotton away from it,since i gave up on benchrest,but im still very intrested in it. I may contribute some,myself.

I have a couple of ibs hunter guns,,30-47,30 aardvark,,,,and some day im going to start shooting cast in them,,,,,,,,,this may give me the spark i need to do it.

The br guns would seem to have the perfect barrell twist rates for cast,,but i can just amagine how much the wind will push a boolit @ 2100-2400 f.p.s.,,compared to a bullet that is trucking along @ 2800 f.p.s.,,,,,,,probaly have to learn how to hold into the wind alot farther!!!

[canyon-ghost]

Mirage board, black and white striped thingy that tells you when the thermals move the image you see upward, above where you should shoot.

And if you see it in a scope, it gets way too clear.

It's a board with horizontal, foot high stripes that alternate black and white. When the image breaks the pattern, the heat (thermals) is changing the image from point of aim.

[Idaho Sharpshooter]

Mainiac,

until the projectile reaches supersonic speeds wind drift is a near linear progression. Once it gets to 1100+/-fps the deviation per fps per mph is difficult to actually predict.

That said, the closer to the target the wind shift occurs, the more difficult it also is to gauge; and therefore, account for in your calculations. It's a 90% computable trajectory, and about 10% SWAG. The reason for that is the transsonic phase. As long as the projectile stays above 1150fps the projectile produces a wake (for lack of a better word) like a speedboat. As it shifts to subsonic, there is an area from about 75fps above supersonic to about 75 feet below subsonic. They term that area the Transonic Zone. The trailing wake begins to catch up to the projectile, and as it drops below the speed of sound (1087fps +/- a few feet based on altitude and temperature), the wake begins to wrap around the projectile, and then passes it. Imagine a big "X" with the projectile in the center. Supersonic, just a V-wake behind the projectile, in the Transsonic Zone, it is the "X" shape, which causes the projectile to destablilize, or, as a friend at Picatinny told me about eighteen years ago, "flutter".

Hold your hand open and level in front of you, palm down, and kind-of wiggle/flap your fingers. The projectile does that. It moves just a little, in two axis separately and/or together. The projectile can move up and down, left and right, or both at once, and almost deviate from the path for just that brief moment.

Once the projectile velocity drops below 1025fps or so, it goes back to sleep. and travels point on, to the target.

Spin a top fast and watch it wobble a bit, then settle in and spin smoothly. It, in ballistics terminology, "Goes to sleep". As velocity decays, the top begins to wobble, and eventually falls over. Projectiles do that, all of them that add spin to velocity.

One issue is that the effect of the velocity and wind direction causes a change in Ballistic Coefficient. Sierra and the Picatinny Arsenal in NJ have done exhaustive testing in a huge underground cavern they test in. The result, is that Sierra now publishes as many as three or four BC's based on velocity. In a condition free environment, they had a lot of scenarios where carefully developed algorithms for flight trajectory based on initial and maximum velocity were predictable. As they moved outside, they started observing erratic behavior.

They have yet to find the definitive, repeatable answer.

The Houston Warehouse was mentioned here somewhere. That's where BR guys began to be able to use the same hold to stick projectiles in one itty-bitty hole. There were no conditions to deal with. Big old storage warehouse, hundred of yards long, a hundred yards or more wide, and about 100 feet to the ceiling. Those numbers are my guesses.

I need to find my notes and review them. All of this information was originally published in Precision Shooting Magazine from 1992-98. As I learned, and could gain consistency, I wrote, and David Brennan printed it. I was privileged to hear from a gentleman at Picatinny, several of the ballistics staff at Sierra, and the occasional phone call from an anonymous gentleman who was employed at Area 51. He called at odd times from about 11pm to about 3am from various locations. All we ever spoke of was ballistics, but I wish he had written a book on the subject after he retired.

regards,

Rich
Sua Sponte

[mainiac]

My hv 6ppc wears 25 inch barrells,and i run the ol girl very close to 3500 f.p.s., its amazing how this will cut threw the conditions,speed is my best answer for dealing with wind drift.

Wondering if the 6ppc is used in cast boolit benchrest?

[Pilgrim Sojourner]

Rich,
Now might be a good time to discuss wind flags (do's, don'ts, and other specific tips).
Tim

[Idaho Sharpshooter]

mainiac,

once you get past 3000fps the BC seems to remain a constant, and while the velocity is constantly diminishing due to gravity, the rate of decay (projectile spin rate) is almost a non variable.
IE: if you start your 308 cast load (150rg semispitzer) with an MV of 3000fps) shooting at 1000yds, the projectile will change BC's twice enroute to the target. Once near 2600fps at 350yds, and once at 1700fps around 725yds. Impact velocity might be 900fps. The projectile also went thru the dreaded Transonic Zone around 900yds.
This is an educated guess on velocities, just for our example here.

Now, we get to RPM. You have a barrel with a 1:12" twist, 26" long. The boolit exits at 3000fps. It makes two complete revolutions inside the barrel. Your RPM is going to be twist X velocity. 3000 X 12 =360,000rpm. It may still be going 345,000 rpm at impact. The spin has very little time, even out to 1000 yds to decay and affect the trajectory. Under normal wind conditions, it is why drift L&R is so much less than drop.

Your point is well taken, and easily explained.

Rich
Sua Sponte

[Idaho Sharpshooter]

Pilgrim Sojourner,

I admit I never mastered flags, but I had a BR friend who did, and tried to explain it. I could read them fairly well after a year in Hunter Bench Rest competition.

Flags have two primary requisites.

1. they need to be very light, so even .5 mph will show up. On changes from the primary condition especially.

2. they have to be consistent.

Most of them are composed of a good-sized vane, with tail feathers. Made of that thin plastic sign board stuff (looks like corrugated cardboard, but of reeeeeeeeeeeally thin plastic) in the shape of an arrow point with a tail. They usually have two or three streamers of that half inch by two feet colored tape you see used by surveyors. They pierce it vertically with a 1/8th inch wire, so it will spin easily. The rod extends about 18" below the vane, and sits in a small diameter piece of tubing.
The tubing is 3 feet long and sits in a same length piece of tubing the same ID as the OD of the upper tube. At the lower end, it ends in a spike, like a 16 penny nail and a small cross bar that you stick into the ground. Where the thicker tube ends, there is a small collar with a hole drilled in it, and a small set screw installed.

You show up at the range, get assigned your bench sequence and set out flags. At a match, they rotate 5 benches after each relay shoots. This prevents any perceived favorite bench being allocated to anyone.

This is also where the "Buddy System" comes in. Either a family member or a friend, goes out in front of you and your bolt out rifle and sets flags between your muzzle and the target frame. You should see the flags in the lower half of your crosshairs, either side of center. If you are at a registered match, imagine a twenty-bench relay, and eighty shooters registered. The day or two before the match starts, with a 5-bench rotation, there are 80 people setting flags (3-5 each) at five benches. I was lazy, and too cheap to make 15-20 flags, so I took advantage of the three to five sets on each bench other people set out.

This is where your opportunity comes to take some young person, or non-shooter out and show them how to make small(er) groups than they would imagine. In Schuetzen, I got my wife's competitive spirit aroused, and she became one of the best wind/mirage dopers at 200 yds out there. I had other shooters ask if she would help them get an initial standard pattern analyzed. Any range, subject to radical temperature changes, has a repeatabae, stable mirage pattern & sequence. Learn it in about three range trips of an hour apiece. Just read the boards and fire a shot. My wife could even give you the duration and pattern of mirage. When you are shooting a 32 caliber single shot rifle and she says "hold half a bullet hole off at 4pm, you do, and the bullet goes in the 1 1/2 inch 25-ring at 200yds; that's a pretty neat thing.

The best mirage focus for your spotting scope viewing is set about 2/3rds of the way to the target.

You know those sunflower plastic thingies that people set out in their yards? The slightest wind will set them turning into the wind, and the head spinning. That, and I used them the first year. It takes about 2mph of wind to start them, and about that much change for them to respond.

A three vane set would be out at 15/35/75yard intervals for a hundred yard match. The closest one is primary, since it will move the projectile the most off target. Then the middle one, then the last one.

I watched Tony Boyer at the Super Shoot at practice. He graciously gave me a two hour Phd level class in flags and mirage. And, yes, he had a mirage board up at 100 and 200. He actually set me behind his rifle and coached me in seeing and adjusting to changing range conditions. I shot his Light Varmint rifle (10.5lbs with scope) under his guidance over about a six minute time limit, and made a group of five shots that measured .081? A group that small is hardly oval.

class dismissed...

Rich
Sua Sponte

PS: I am not brilliant, but I listen to the top shooters, and I take lots of notes.

[Pilgrim Sojourner]

Rich,
This is enlightening. Your time and experience-sharing is much appreciated.
Tim

[Idaho Sharpshooter]

Knowledge not shared is knowledge wasted...

[mainiac]

wind flags are vital to shooting little groups,aint no doubt about it......

I always shot the let ups,and as a result,on days with very quick switching conditions,i usually didnt have to worry about 1st place!!!

[Idaho Sharpshooter]

mainiac,

I tried to, but reading the mirage well enough to identify that cycle, and then time it well enough for 5-shots on target under .100" at 100yds in 7.5 minutes took a lot of matches to quantify.

This is just a bit of a primer, learn what you can from it, and apply it downrange.

Rich
Sua Sponte

[mainiac]

i shot mostly score,,in maine,there is no group shooting.

Toward the end, i ended up hooked on the hunter gun.Something about drilling 1/16th dots with a 6x scope,that you cant see nothing out of,,was a huge thrill!!!

What would be your top pick for a .30 cast boolit,in a 30-30 size case?

I have a couple of ibs hunter guns here,and really should try cast in them....

[Idaho Sharpshooter]

Boolit selection is about 90% based on twist.

My preference would be about 50% bore riding nose and 50% bearing surface. The old saying rings true "the best way down a dark road is in the middle..."