first shot

[runfiverun]

this is a little informal poll not a voting one just a discussion...

so where does your fist shot go?
you know the one.
when you first sit down at the bench and put the rifle/pistol boolit/bullet on paper.
i don't mean burn it in the berm.
where in relationship to the group does it go.
this can include jaxketed also.
is it high? high right? high left?

[Eutectic]

Good thread Run!

With boolits probably 80 to 90% shoot high. The amount high varies with the gun, boolit, load, and lube and also temperature. As was previously said I get a going 'left' along with high below freezing. I don't know why, but would like too!

I'm going to put a left hand twist barrel into my lube testing and see what happens though!

Eutectic

[waksupi]

In my main hunting rifles, they tend to go a bit high, if I have cleaned the firearm. If I don't, which I usually don't, most of the times they are well within hunting accuracy, say maybe an inch difference.

[shooter93]

Lamar....all my shots go exactly where I'm aiming.......lol.

[Recluse]

Depends on the gun and ammo.

For instance, in my Model 29 with the 8 3/8" barrel, my magnums go dead on where the gun is sighted in for. But the Specials shoot about two/two-point-five inches high from POA at the normal 50 feet, handheld.

My Model 686 with the same length barrel puts everything exactly where I aim regardless of the ammo being fired. Go figure.

My .45s generally go a touch low until I adjust my eyeball sight picture.

The 9mms have the biggest variance of all. With lead loads, regardless of boolit/powder configuration, they shoot WAY low--I'm talking four to five inches at 50 feet. But with my jacketed rounds, regardless of projectile/powder configuration, they shoot dead-on where I aim.

The hunting rifles do just like Waksupi's.

:coffee:

[williamwaco]

this is a little informal poll not a voting one just a discussion...

so where does your fist shot go?
you know the one.
when you first sit down at the bench and put the rifle/pistol boolit/bullet on paper.

Years ago when I was an active hunter, I used three shot groups for accuracy testing but for sighting in, I used the first shot only. That is, I adjusted the scope to put the first shot at the poi and let subsequent shots walk away from that spot if the rifle in question was prone to do that. - Yes it took a long time to sight in.




Five, I think you already know the answer.

- - - - - - -> It depends.




It is different for every gun I own. Only rarely will a rifle put the first shot in the correct place.

I find this to be MUCH less of a problem with handguns because I am just not that good.


.

[chboats]

Most of mine go high or high right. I have a 458x2 that will put the first three in a nice clover leaf and the 4th will drop 2 to 3 inches at 100yds

Carl

[btroj]

Can't really say, I don't shoot from a bench very often.

I will say that the 375 lately has put first shot from a non cleaned barrel right withthe rest at 50 meters.

I find a clean, cold barrel usually put a shot high, usually left.

[I'll Make Mine]

Honestly, I can't say -- I can't see the holes from the bench (no scopes, yet), so I can't readily tell which shot in a group was the first by the time I get to the target.

[1Shirt]

I seldom clean with cast loads unless I suspect leading. From a cold fouled bbl, with most of my rifles I find the first shot to be somewhat high and left. At 50 yds this tends to be anywhere from 1/2 inch to an inch from the next 3 to 5 shots in a group. Doouble that at 100.
1Shirt!

[KYCaster]

Well...........this is a loaded question if I ever saw one!! Like WilliamWaco said, "...it depends."

I worked up a hunting load for my Marlin 336 in 35Rem with MG rifling that shoots under 2 in. at 100 day in and day out. I soon found, though, that when the temp went below ~36 F the first shot was about 8 in. high. A change from Thompson's Blue Angel lube to Bull Shop Speed Green cured that. Now the first shot is at POA, and I don't think it will ever get cold enough here to change that.

Two years ago, after about 300 rounds I decided the gun needed a thorough cleaning and scrubbed the barrel to bare metal....till patches came out without a speck on them. The next shot was 18 ins. high! I panicked cause this was two days before deer season opened. I shot up the remaining 12 rounds I had loaded and each successive shot was a bit lower.....like 12", 9", 7", 6", etc.

Back to the loading bench and after 36 rounds I had two successive five round groups at POA. So that's 25+ rounds to season the barrel to that load. Now, when I put that one in the safe for extended periods, I pull a bore snake through it and then push a very tight patch wet with Speed Green through it.

It's had about 200 rounds since that thorough cleaning and I can count on the first round going to POA and the first three round group less than 2 ins. After that the group starts opening up to about 4 ins. and centered slightly high and left.

22LR comes with it's own set of problems. I've found that when changing brands of ammo I can expect to burn 5 to 15 rounds before the gun settles into POA.

The Ruger MKIII Hunter is usually what I pick up for squirrel, feral felines and the odd varmint and targets of opportunity around here, so I'm careful to run a couple of mags of its favorite cheap ammo through it at the end of a range session. And, like the Marlin, a brush through the bore followed by a tight patch with Slick 50 or Rem Oil seems to keep it shooting to POA.

So, yeah, it depends. Sometimes it takes a lot of shooting to figure out what's going to work for a particular gun.....don't you just HATE that? :mrgreen:

Jerry

[Idaho Mule]

run, I love this question!! and it applies to me today. Loading for my brother's .356 Win in a model 94AE. Shooting rcbs200fngc with 25 gr. of A5744, WLR primer. Boolit cast of #2 alloy and sized @ .359. Range of a whopping 25 yds. because this gun had proven to shoot low before.First shot was 6" low and 1/2" to left. OK, I could have been off the 1/2" to left, but was still way too low. Did some measuring, front sight is 3/4" above bore center and rear sight is topped out, same problem I had a cpl yrs ago. Looked at midway catalogue and found a shorter front sight to order. Only problem is, the smallest they list is a Marbles at 1/16". I would prefer one of 1/32".
Anyway, oldest son and I shot just because. Gun wants to shoot good that's for sure cuz we did shoot some nice grps after we started aiming 6" high. Enough BS, shots were all centered, just 6" low. Do you know where to find 1/32" bead?

[runfiverun]

you wouldn't be the first to run a file over the front sight,a little ges a long way.

i started this thread to see if there was a pattern, and so far there seems to be the one i thought there was.
more posts will help see if it develops to a better pattern across the board.

[40Super]

On my Comp 1911, if the first isn't in the group circle it is high left about an inch.

Other handguns I haven't consistantly noted which hole was the first,so no help ther.

On my hunting guns the first shot was usually right on because I sight them in with cold barrels,(one shot,let sit for 5 min, 2nd shot, sit for 5min,3rd-10min ect), I always want to know where that cold barrel first shot goes. If I shot faster, generally the shots would go up after the first.

[HangFireW8]

I run a patch through the clean barrel coated with the same lube as the boolits I'm about to shoot.

Sure saves a lot of time at the range.

[popper]

40SW, 30-30, AR 308 - off bags, always high. Bore always has a coating of ed's red. Rifles are scoped and seldom rezero'd. 2 pistols, high and left. Jacketed is same but less, if I remember, long time since shooting those. I think my shooting would be better with an opposite twist.

[mainiac]

I think it depends on the gun,but on my leverguns, i have also found the first shot to go high/left,,never give it alot of thought,until now!!!!

Im currently shooting a rem 700 sporter in .222, and that gun shoots ON, no matter clean bore or dirty, cold or warm, dont matter.......................a typical .222!

[Wolfer]

With my homemade lube if I haven't shot the gun for a couple weeks the first shot will be slightly high. If the barrel has been freshened in the last day or two they seem to be ok.
Since I'm primarily a hunter I'm mostly interested in the first shot from a cold fouled barrel at the crack of dawn.
During hunting season I make sure I keep my barrel fresh every day or two.

[jdgabbard]

Every single one I own shoots just low of the target, with the exception of three loads for one handgun. Two of those are on the money, the other shoots a tad high, and a tad left. Those are all handguns. The rifles are all sighted for the loads.

[Dave C.]

If I do my part my Clark Long Heavy Slides (1911's)
remove the X from the target. First shot in a match to
the 270th shot of the match. The only change is in the
shooter not the gun or the ammo.

Good health and good shooting
Dave C.

[chutesnreloads]

YEP..depends on the gun and some on the load too.My two worst offenders are a 10-22 that always shoots high right with 1st shot out a cold barrel and a tikka .243 that always hits high to left with 1st shot.I suspect all guns do it just some more noticeable than others.

[UBER7MM]

YEP..depends on the gun and some on the load too.

Yep, Some guns like a fouled bore. Others shoot well first and last shot. Each gun is a law unto it's self.


Keeps it interesting.

[reloader28]

If mine dont go into the spot I'm shooting, I dont trust the load.
I'll keep working til I get the first 3 to go in the same group.

If its a condom bullet, it better be around 1/2"@100yds.
If its boolits with a scope, it has to be under 1 1/2"@100yds.
If its a boolit with open sites, I'll settle for 3-3 1/2"@100yds.

[BLTsandwedge]

My right foot.

[williamwaco]

You didn't ask this question but I find when accuracy testing that when I change powder ( variety, not charge weight ) the first three shots with the new powder will always go wild.

I am not sure but I think this is related.

.

[KYCaster]

You didn't ask this question but I find when accuracy testing that when I change powder ( variety, not charge weight ) the first three shots with the new powder will always go wild.

I am not sure but I think this is related.

.



I think he's looking for the answer to a question he didn't ask. :veryconfu He's just going at it in a roundabout way so he can get an unbiased opinion.

Maybe some day he'll let us know what's on his mind. :popcorn:

Jerry

[williamwaco]

I think he's looking for the answer to a question he didn't ask. :veryconfu He's just going at it in a roundabout way so he can get an unbiased opinion.

Maybe some day he'll let us know what's on his mind. :popcorn:

Jerry


He did say he was noticing a pattern. I hope he will let us in on it because I have wondered how to fix that problem for almost 60 years and I have never even seen a pattern.


.

[runfiverun]

you guy's are on track.

i want to see some more responses.
the answers are very,very telling............
i'm gonna let this go another day or so.

[waksupi]

I seem to recall Felix at one time said if you were shooting his lube, run a patch of Ed's Red through the barrel when you were done shooting, next time out, run one dry patch through, and the shots will all be in the group.

[runfiverun]

ric is getting much closer.

[btroj]

In the 375 I have been using Bens Red lube. I have been cleaning the barrel each time out but am cleaning with straight ATF, the same bottle I used to make the lube. I run a couple dry patches when done but it leaves a light film of largely the same thing laid down by the lube. Not sure how much more consistant a first shot layer I can get.

[runfiverun]

brad read eutetics post in the quest thread.
there's one more thing you could do,but you'll have to test it for yourself.

[popper]

So you are figuring a velocity change due to the lube or bore 'seasoning'? Or recoil change?

[waksupi]

Lamar, are you working your way up to tell us to quit cleaning the bores so often? Works for me, I don't remember what year I actually "cleaned" my .358 Win the last time. Closest thing it usually gets is a dry and oil if hunting in rain or snow. My first group this morning was nice n tight, and I had shot a lot yesterday without touching the bore. No need, it's shiny as can be. I imagine I am well over 1000 rounds since last cleaning it.

[btroj]

I think he is working up to wondering if a small powder charge reduction in the first shot might not let it go Ito the group.
Maybe have a load that shoots a groupin a specific location and a special charge that is for first shots only. It would have a reduced charge that would let that round impact into the same group from a cold barrel.

Run can be a bit obtuse at times, I am finally figuring out how to read his posts.

[btroj]

I do have a question for Run, do you think that running a patch damp with a light oil, something like ATF, then a dry one before that first shot could make a difference
Would "loosening" the fouling in the cold bore make a difference?

[40Super]

If the first shot always goes high, well just aim low that first shot:razz:

[runfiverun]

brad got it.
the first shot as we know is usually high left [talking rifles here small bore stuff 358 down through the 22's]
we know that the lube changing in the bbl causes friction variances in the first shot and many have [i'm sure] seen the first number across the chrono higher.
the wet bore patch will help alleviate this by conditioning the bore [much like mikes MML lube overcomes this just in reverse]
however by adjusting the load down about 4-5% will also overcome the dry condition.
i tried this before and eutetic really wrung this out,in the quest lube thread.

this is just a little something else we can work with for those hunting loads,or cold target shots.


anyway.
the pattern i was loking at was the high left shots [i knew they would go there] i just [last week]shot 12 different rifles 6 shots each and 11 of them went high left, just one went slightly low left.
this happened with my complex moly lube with atf and was also the most recent rifle i had shot.
the other boolits were lubed with bac, my e-purple,e-yellow [not modified],carnuba red, and 60-40 b-wax/ xlox with lanolin.
the calibers included the 223,22-250,220 swift,7x57,8x57,308 [x2],30-30[x2],30-06,and my 358 win.
all bolt action rifles except 1 30-30 levergun [the one that was a little low left].
i was gonna include the ar with my moly complex too but little girl wasn't havin any of the test stuff,and just started shooting clay birds at the 100 yd line.

[runfiverun]

i may repeat this test with my 357,44-40,all three 44mag,and all 4 45 colt leverguns,plus both
375's and the 45-70 levergun also just to see what's up with them too.
i think i missed a couple of my leverguns though.
if i do i think i will throw in some recluse lube and my b-wax modified version in the mix also.

and for those that wondered why i threw in the jacketed also.
i wanted to see what kinds of replies i would see there and if they differentiated between a clean and dirty bore.
i have a couple three jaxketed only rifles and know where they shoot thier first shot compared to the group also.
it's different for many of them like was pointed out.
[and it is usually the first two shots that are together]shrugging here]
however, my really accurate ones show a quite similar pattern amongst themselves too.

[Eutectic]

I'm still testing, but the 4-5% powder reduction works dropping the first shot into the group..... so far! It changes as temps go colder it seems. I'm at 19F now.

I have had pretty good results in several guns and with three different lubes (all formulated during the 1254 posts on the Quest thread.)

Of course, a lube formula that eliminates cold starts hot, warm, cool and below zero is what we need!

Treating the bore some way could be balanced to gun/load to work too for the first shot to group dead-on I'm sure.... But I haven't pursued it. I have three guns I will use hunting this winter. My varmint and rabbit hunting can't get by with just one bore treatment as these guys may need several "cold starts" in one outing.

I have a hunch that when it gets below zero that a cold start could be a half hour instead of a day. I plan to see what happens as winter comes on. I'll leave gun and ammo outside and shoot say four hours later.... If I don't get a cold start I'll go overnight and try it (8 hours). If I get a cold start at 4 hours (which I think I will at say 15 below) then I'll shorten the time to see just what I can get away with.

It will be easier to have special shells separate for the cold start if they occur an hour (or even a half hour) apart and I'm callings coyotes for an example where shots have that amount of time in-between.

It appears adjustments will be gun, load, temperature specific as well. Hope we get a lube formula that will handle it eventually.

Eutectic

[btroj]

It is those multiple cold starts while hunting that bother me the most. My 32-20 is really picky about lubes in the cold. It would be a great squirrel rifle but I need to be able to hit something with it!

Target shooting on the range isn't a big issue with me, I can fire a few into the berm first if needed. Hunting a the place where I want to know where that first shot will be, every time.

[MT Gianni]

run, I love this question!! and it applies to me today. Loading for my brother's .356 Win in a model 94AE. Shooting rcbs200fngc with 25 gr. of A5744, WLR primer. Boolit cast of #2 alloy and sized @ .359. Range of a whopping 25 yds. because this gun had proven to shoot low before.First shot was 6" low and 1/2" to left. OK, I could have been off the 1/2" to left, but was still way too low. Did some measuring, front sight is 3/4" above bore center and rear sight is topped out, same problem I had a cpl yrs ago. Looked at midway catalogue and found a shorter front sight to order. Only problem is, the smallest they list is a Marbles at 1/16". I would prefer one of 1/32".
Anyway, oldest son and I shot just because. Gun wants to shoot good that's for sure cuz we did shoot some nice grps after we started aiming 6" high. Enough BS, shots were all centered, just 6" low. Do you know where to find 1/32" bead?

My long gone 356 was a poor shooter with irons. I put a scope on it and it improved 100 %. I would put a peep on it before staying with the Winchester blade.

[Mal Paso]

Quite often that first shot will be in the x-ring then I'll struggle to get another 1 or 2 close to it. Prolly Sick-O-Logical cuz I'll do it several times during the day. (44 Mag DAs, offhand, Iron Sights, usually 25yds) Could it have anything to do with shooting next to a guy with a wounded Right Foot?

Thanks to the fine folks here I've changed Fit, Powder, Lube and Gun Geometry. Bore gets a brush and dry patch, no solvent. Cylinder and crane need lube removed.

I kid you not. When I started shooting lead, there were times I pulled streamers of lead from the barrel.

[popper]

Just for grins, I'll SWAG this and ask if @ 100 fps diff(~1/2 gr), is it lube or cold bbl dimensions causing the high left 1st shot? At an SD (+- 30%) of ~20(+-.1 gr.) it would appear that lube reduces fps with increased friction. But we lube to reduce friction. So swabbing with lube before a cold shot would solve that problem.

[btroj]

But if that lube is high in wax components that get thicker with cold, like carnuba, then it may actually make things worse, not better.

It also isn't practical to swab the bore before each cold shot in a hunting situation. Deer hunting isn't an issue to me, squirrels are. With my 32-20 I can have 1.5 inch flyers with the first shot using some lubes in a cold barrel. That means misses much of the time. Not acceptable.

[runfiverun]

whether it's either lube or cold bbl dimensions it's still a lube problem.
that says you have too much in the bbl and if it [the bbl] shrinks a little bit it's causing the lube to clog things up.
a dry patch would eliminate the excess lube and also the cold bbl issue.

what i keep on seeing is that we swing past the zone too far for the cold, then back too far for the hot.
ruining our chances on the other end.
gear and i have talked about this several times we need a lube just barely good enough in the cold and just barely good enough in the hot.
or it will fail on one or the other.

in brad's 32 personally i would look at a softer wettter lube and for 3-5 shot grougs that hold together.
no more than that.
something with atf,or 2 stroke oil added to them.
that would definatly get you through the season,and has been the best answer to the first shot flyer closer to the group i have found.
it's pretty easy to specialize, it truly is hard to generalize a lube.

[popper]

The evidence from Eutectic and chrony results indicate the 1st shot is maybe 5% faster, independent of the rifle or lube used(I'll make that assumption anyway). Typical powder drop & CB weight variation will be 1%, so let's forget load variables. I clean with Ed's Red and just leave it, no dry swab before shooting, 1st is high. So the conclusion of this thread appears to be that fps causes it (high) and lube should be only enough to prevent leading? The ambient temp range would only apply to follow on shots. The shooter gets to compensate for the 1st any way that works. Is there an error in my logic?

[geargnasher]

I'm late to the party but here's my two pennies-worth anyway.

I think a LOT of this first-shot flyer thing has to do with FIT and how soon obturation is achieved. Why do I think so? Because setups that allow for absolutely minimal lube blowby tend to throw that first shot a lot less out of the group, and also tend to throw them high from a dry barrel. Loads that allow more blowby are less affected by dry barrels for obvious reasons.

If I patch out with Ed's Red, no scrubbing, just a damp patch immedietely followed by a couple of dry ones before storage, by first shot is in the group provided the lube and temperature are matched. If I leave too much Ed's in there, or let it soak enough to remove the "season", the first shot or two is always low, very low. Same with oil. Too much slickum in the barrel and the pressure (and thus velocity and POI) drop.

Right twists generally throw first-shot, dry-barrel flyers high and left, left twists throw them high and right. Boy, I'd love to know why!

Cold weather and hot-weather lube from a properly-fouled barrel throws first shots high every time.

Hot weather with cold-weather lube may or may not throw the first shot out of the "group", but usually throws the third or fourth shot wide (sometimes randomly, sometimes not) in a consistent pattern. One notable example is using MML lube in 100-degree weather with one of my rifles in particular, it will print two separate groups about two MOA apart, with about 20% of the shots being low and left. Done this several times on different days, a perfect example of "purge flyers".

Eutectic's C.O.R.E. concept is the whole thing, but don't forget to include pre-engraving blowby among the items on the list of "Residuals Encountered" when doping it out. FIT and SEAL from ignition to muzzle exit affect things as much as temperature does, part of the reason that lube formulations become so complicated, and above all, subjective.. Fit affects everything.

Gear

[40Super]

Would it not be Yaw, that causes the high right for right twists an high left for left twists. I believe in some long range shooting that yaw is a measured effect on trjectory. Could the lube be drastically increasing that effect?

[runfiverun]

i think the thickened lube is affecting friction causing a slight pressure change.
changing to a softer lube will change things considerably [it will generally move the first shot closer in the group]
but has the down fall that gear pointed out.

before yaw becomes any kind of an issue you need speeds in the 2400 fps and over range.
and even then you really need to have a badly flawed boolit for it to become an issue.

[smokeywolf]

Grease or lube is a double edged sword. It reduces metal to metal friction/resistance/galling. At the same time the lubricant itself becomes an obstacle that the boolit has to overcome; to push and or move out of the way or down the barrel.

Too much lubricant and the first boolit has to clear it. While the complete absence lube, like Gear said, and you have a dry surface (metal to metal) that that first boolit then has to overcome.

That first boolit establishes surface conditions in the barrel; temperature, lube/moisture, friction coefficient, that tend to change less after that.

smokeywolf

[Eutectic]

i think the thickened lube is affecting friction causing a slight pressure change.


In gun barrel dynamics we all delve in an area that the human mind and its ability to understand has trouble with. It is time I speak of; in our case, elapsed time. I have noticed both in myself and others that very short time duration can 'trick' us! It is human nature it seems to think (or group) microseconds as 'instant' and not having a duration; but oh boy it does! It seems the mind has good understanding of time down to the duration of our reaction time and then things get cloudy for all of us. If this time duration affects other variables in what we try to figure out it becomes more complicated yet!

I say this because we have to trust the physics we know that are going on in our gun barrel.

Run's first line caused me to ponder out loud all of the above!

Time pressure curves.... If we had hard copies of Time Pressure Curves for a given cast boolit load for a baseline; and then we tested a 'cold start'...... I think we would see what is going on better.

While we struggle with microseconds our powder does not!

I think therefore, that increased (or different some how) bore friction during a 'cold start' delays our boolits start and bore travel in mere microseconds. Our powder reacts to this by acting (and performing) like it has a faster burning rate. In small amounts, Maximum chamber pressure increases, muzzle velocity increases, and the shot impact is usually high. (especially lever guns)

I have two .22 Hornet barrels that are almost identical in chamber dimensions and fit. One is a right hand 1 in 12" twist, the other is a left hand 1 in 12" twist.
I am just getting into 'cold start' patterns between them.

Both are shooting (very well I might add) my Polybutene Felix lube now with a 8.5 bhn boolit at near 2600fps. Maybe Gear's comment on 'fit' have something to do with this ability because I would have bet it not possible with so soft a boolit!

Our answers here includes 'microseconds'.......

Eutectic

[popper]

Arrrg. More variables! Larry Gibson has the equipment, possibly he has some pressure/temp data he could add. I agree with the 'fit' that gear mentioned. Spin-drift in the US should cause a right drift. Analysis does show a helical-cycloidal path the the target that begins left and up. It can start with a large radii which decreases with damping or stability (function of distance and velocity). Just had a curious thought. What does a non-lubed PP CB do? Where is pdwg shooter?

[1Shirt]

Ahhhh---tis a wonderment? Good thread!
1Shirt!

[geargnasher]

Arrrg. More variables! Larry Gibson has the equipment, possibly he has some pressure/temp data he could add. I agree with the 'fit' that gear mentioned. Spin-drift in the US should cause a right drift. Analysis does show a helical-cycloidal path the the target that begins left and up. It can start with a large radii which decreases with damping or stability (function of distance and velocity). Just had a curious thought. What does a non-lubed PP CB do? Where is pdwg shooter?

I think you're confusing spindrift with Corlois Effect. The latter is the effect, noted as something on the order of 10-15 inches at 1,000 yards with a .308 if I remember right, of the earth moving the target during the duration of the bullet's flight. If you shoot due geometric north, the bullet will strike left of the aim point due to the rotation of the earth after the trigger is pulled. Spindrift is created by air pressure on the nose of the bullet as it spins and the pressure differential between layers of air molecules at the surface of the bullet, and much more noticeable at shorter ranges. It would take several pages to describe it in detail but that's the short version.

The damping of the yaw-induced helical spiral is a result of a well-balanced bullet that has the center of pressure well ahead of the center of gravity. All bullets experience a sort of wobble as they exit the muzzle due to muzzle blast or unsquare bases, and this is dampened within a few thousand caliber lengths by the spin. By a hundred yards, most supersonic bullets will be as stable as they are ever going to be, so the spindrift, winddrift, drop, and various effects of yaw are the only real factors, none of which are significantly affected by bore condition as far as I can tell.

The reason for high or low first-shot flyers? I think it must be frictional conditions in the bore affecting the burn curve and peak pressure (the way energy is transferred to the bullet vs. the barrel as kinetic energy and heat energy, respectively), and our old nemesis barrel harmonics. Alter that burn curve just a bit, like 5% powder charge, and you'll see the same change in POI much of the time as you do with a cold barrel shot.

Gear

[mainiac]

This country-bumpkin would like to ask one question....

If this first shot has less/more pressure,and this is the reason for the high flier, then how to explain certain loads that have E.S. chrono numbers that are 80-100,,and these loads will shoot tiny groups with no fliers.


I took 2 semesters of physics,,i hated it,and still hate it! And i didnt stay at a holiday inn!!!!

[HangFireW8]

If this first shot has less/more pressure,and this is the reason for the high flier, then how to explain certain loads that have E.S. chrono numbers that are 80-100,,and these loads will shoot tiny groups with no fliers.


Benchresters have debated for years why flat-base bullets shoot so accurately at short (up to 300M) range with poor Extreme Spreads. Long range shooters know that these ES are not suitable for their long range (over 300M) target work because vertical stringing will result. They are using boat-tail bullets that have a smaller MOA accuracy at long range than short range. This of course is due to settling mid-flight, the long range bullets do not continue to diverge from the ideal flight path as much in the latter portion of flight as the initial portion. Shooting accuracy is not geometry.

I think the posters on this thread are on the right track, from a dry unlubricated barrel, the time/pressure curve differs, the initial friciton pressure is higher, this causes a quicker more complete burn which in turn leads to a steeper acceleration curve, all of which results in a flier compared to following shots.

From a heavily lubed barrel, a flier is caused by pushing out more lube than following shots. It is also has a very different acceleration curve, since it starts easier (unless the lube is so heavy there are hydraulic issues), it gets moving earlier and the burn is not so efficient and the acceleration curve not so steep.

That's why for cast boolits I push a patch through with a little bit of the lube I'm using. For jacketed I often leave the barrel a little dirty.

HF

[felix]

Ah! Mainiac, WHERE the boolit exits the muzzle is far more important than WHEN it exits the muzzle. The vibes in the barrel, and only the vibes, determine that WHERE point. But then, the collection of vibes is a function of the ACCELERATION of the entire mass of the gun, including the boolit and all ejecta. The point of the barrel that is moving the slowest would be the most accurate point of that barrel. The smoother the wave, the more variation of velocity is allowed for the same accuracy. This is why certain loads can fine tune the system, as well as a barrel tuner. ... felix

[geargnasher]

Ah! Mainiac, WHERE the boolit exits the muzzle is far more important than WHEN it exits the muzzle. The vibes in the barrel, and only the vibes, determine that WHERE point. But then, the collection of vibes is a function of the ACCELERATION of the entire mass of the gun, including the boolit and all ejecta. The point of the barrel that is moving the slowest would be the most accurate point of that barrel. The smoother the wave, the more variation of velocity is allowed for the same accuracy. This is why certain loads can fine tune the system, as well as a barrel tuner. ... felix

Perzactly. Small variances in the pressure/time curve, especially the initial pressure build, affect the position and size of the muzzle at boolit exit, which is going to throw the first shot off a lot more from "average" with a given load than a few FPS and time to target (gravity drop) will at shorter ranges. Bore condition at each shot plays a big role in how powder pressure builds, and thus the barrel wiggle.

Gear

[popper]

Perzactly Got to remember that one. Yes Corlois Effect is a function of earth spin. Gravity is a factor in spin drift. Yesterday (~70F) I got a 2" high 1st, 1" high 2nd from 336 RD311165 lubed with mazzola, HT COWW==, 30 gr LeverE. from a DIRTY bbl. Like not cleaned for a month, after ~100 rnds. Same results with the 308. No left shift like I get with LLA or recluse. Sure have a sore rotator after ~ 250 rnds. Got some castor oil to try, that stuff sure is expensive - ~$3 for 8 oz. Both bbl were streaked when I started, haven't checked this morning, but accuracy was the same when I finished.

[Win94ae]

So far, none of my pistols have a cold bore deviation, whether they are clean or fouled, whether using cast or jacketed.
My rifles usually have a clean bore deviation at about 2 to 3MOA low using jacketed bullets; sometimes not, it seems load specific.
My 30-30 with cast tumble lube, has a cold fouled bore deviation at 4MOA low, but if the bore is clean it doesn't have a POI shift.
I thought if I changed from straight Alox to a 45/45/10 mixture, I would see less of a shift but it seems to have had no affect.


http://www.youtube.com/watch?v=uozqOkWnUxc

I can count on the cold fouled bore POI shift to be precise so I'm just going to take it into account... (I could also try a clean patch down the bore beforehand.)

The cast cartridges were all shot in 80-98 degree F temperatures.