Gene's Tuner @ 200 yd

[Jerry Reisdorff]

Shot my 30 BR this Sat @ 100 and 200 yd's - what I saw was that I needed a different tune at 200 to make 3/4 inch 5 shot round holes.

It this normal or do I need to change something?

Jerry

 

[Gene Beggs]

Shot my 30 BR this Sat @ 100 and 200 yd's - what I saw was that I needed a different tune at 200 to make 3/4 inch 5 shot round holes.

Is this normal or do I need to change something?

Jerry

Jerry, if the rifle is in tune at 100 yards, it will also be in tune at 200, 300, etc. With tuning, all we are doing is timing bullet exit to coincide with one or the other stops of the muzzle. It has nothing to do with yardage. Some say you have to retune the rifle for a headwind, tailwind, left crosswind vs., right etc. That makes no sense to me. External ballistics apply only to the bullet's flight path after it leaves the muzzle.

If you had to change the tune at 200 yards from that which shot well at 100 yards, my question is, "Was the temp the same; how much time elapsed between the last group at 100 yards and the first at 200?" A ten degree increase in temperature will make a noticeable difference in vertical.

What many shooters do not understand is the fact that tuning is condition specific. The rifle will be in tune only as long as there is no change in atmospheric conditions. You cannot set the tuner to a specific position today and expect the rifle to remain in tune tomorrow unless there is no change whatsoever in atmospheric conditions.

Before the first match of the day, always zero the tuner by turning it all the way in and backing it off one revolution, placing the reference mark in the 12:00 o'clock position. This will always be your starting point regardless of location or temp.

Later,

Gene Beggs

 

[alinwa]

If this is the case Gene then how DOES the trajectory compensate for velocity differences?


IMO Jerry you must tune for each specific yardage since the basis of the tuning concept relies on convergence of different trajectories.

al

 

[mike in co]

al,
my limitied knowledge,
if it always leaves the muzzle at top dead center, then it may hit(poi) different at 200, than at 100, but the 200's should all be close....no need to retune if the conditions did not change from 100 to 200.....( all the 200 yd bullets have similar velocity at 200, and the bbl/node/timing was all the same)

mike in co

 

[Gene Beggs]

If this is the case Gene then how DOES the trajectory compensate for velocity differences?


Al, trajectory does not compensate for velocity differences; how could it?

Having the bullets exit when the muzzle is stopped at the top is what compensates for slight variations in muzzle velocity.

Later,

Gene Beggs

 

[alinwa]

If this is the case Gene then how DOES the trajectory compensate for velocity differences?


Al, trajectory does not compensate for velocity differences; how could it?

Having the bullets exit when the muzzle is stopped at the top is what compensates for slight variations in muzzle velocity.

Later,

Gene Beggs

?????


Of course they do.... the only way a bullet that's running 40fps slower than another to hit the same poi is for it to be launched "higher", at a steeper launch angle. Two football passes can reach the same receiver, one a lob and the other a bullet......but only because the lob is sent higher.


al

 

[eww1350]

I'll bet "Kathy" could explain it.....just get him a "spam samwich" and some "Moutain Dew"...he could go on for hours (pages)...

 

[Gene Beggs]

?????


Of course they do.... the only way a bullet that's running 40fps slower than another to hit the same poi is for it to be launched "higher", at a steeper launch angle. Two football passes can reach the same receiver, one a lob and the other a bullet......but only because the lob is sent higher.


al

Al, I understand your analogy with the football passes but I do not believe it applies to tuning/shooting a rifle.

Yes, if the shooter had some way of knowing which round was going to be slow or fast, he could compensate by holding a different point of aim but that is not the case.

I am well aware of the sine wave that results from gradually increasing the powder charge and its affect on grouping. Vaughn describes this perfectly in his book, "Rifle Accuracy Facts" chapter 4 under, 'Special Benchrest Gun Problems.

On page 85, Vaughn suggests that one should operate on the 'peaks.' By 'peaks' he means the stop of the muzzle at the top. I have found equally good results operating at the stop at the bottom.

Regardless of the load, my tuner can switch the bullet's exit timing from a positive peak to a negative peak by rotating exactly one revolution. If the rifle is completely out of tune, the bullets are exiting in the middle of the swing where variations in velocity cause maximum vertical dispersion. In this case one can get the rifle perfectly in tune by turning the tuner a half turn in EITHER direction. Making a half turn in one direction times the bullets exit to coincide with one of the stops of the muzzle; a turn in the opposite direction times it to the other.

I have seen no difference in grouping whether the rifle is tuned to the top or bottom stop.

Hope this helps.

Later,

Gene Beggs

 

[tim in tx]

jerry sir

sounds like you may have developed some velocity variance that is scattering them by that it is changing the exit timing around.the rounds in the ammo box facing up hitting the table with .001 neck tension a little too hard can somtimes hammer the bullet down into the case and go from jam to jump,if not you might run some chrono test and see if you did develop a problem.genes tuners do not fix velocity es problems,they simply bring the rifle back into tune as it would be on a powder change tuned barrel.if you have velocity variance you have to fix that first for longer ranges than 100yds.most of the time es wont hurt you at 100yds as i am sure you know but anything longer shows up somtimes .if you want to get the barrel on the upswing at the bullets exit to correct for velocity variance you will have to add a chunk of weight to slow the swing down and it is a huge pain to do but it does work.setting a tuner in winds that create poi shifts make it harder to say if it is really in tune,if you set any tuner in adverse winds it seems it will be in tune somtimes but not all the time hence inconsistancy ,the wind can blow you in giving false comfort just as easy as it can blow you out which can cloud the judgement if setting the tuner by groups shrinking outside,if you develop a formula as gene stated i would go with that. it just sounds to me like the only way to adjust a tuner consistantly for groups,but with low es for longer yardages as is with normal barrel configurations.good luck sir.hope this helps tim in tx

 

[bryan]

Jerry

I think what Gene is trying to get across is that the tuner modifies Internal Ballistics.........which involves everything BEFORE the bullet exits the barrel. After the moment of exit, not one thing about the rifle or load or gun handling has any bearing on what that bullet is going to do.........it's all up to the bullet at that point. 100 yds, or 1000 yds, that bullet is on it's own.
Bryan

 

[Boyd Allen]

If we go back to Varmint Al's graphs, his contention was that a longer barrel (24" on a short range center fire Benchrest rifle) or a weight at the muzzle, or a barrel that is thinned in the middle can all slow the muzzle swing to the point that bullets exit the muzzle as it rises, relative to the target. This would then mean that bullets that exited slightly later would leave the barrel when it was pointed higher than those that exited earlier, thereby reducing the amount of vertical produced by a given amount of velocity difference within a group. The kicker is that if this is how it works, the convergence of trajectories would be distance specific, requiring a different set of velocities or different barrel and/or tuner configuration to produce the same effect at a different distance. You will notice that I didn't say that this theory is correct, since I have no way of verifying it, nevertheless I think that it definitely merits consideration.

 

[bryan]

Boyd

I can't follow the math. Varmint Al is a smart guy and talented with the software, but imagine, if you will, this scenario. Super-duper high speed photo of the bullet exiting the barrel at the very top (or bottom) of it's verticle swing. Great. Now lets do it 4 more times with exactly the same pattern. EXACTLY THE SAME PATTERN. At this point, the rifle, bags, shooter, powder and bullet have theoretically behaved in an identical manner. OK?
Now, if the bullets were exact clones of each other, and the conditions were 100% constant, would those bullets not produce groups at 100 or 200 or 300 yards that would be consistant with the MOA of the range being shot?
I guess what I am saying is that if the combination is the nuts at 100, but not the nuts at 200, something is wrong with the stability of the bullet at different ranges. And that has nothing to do with the bullet while it is still in the barrel. You can send it on the perfect course to the target, but It has to be capable of maintaining it's course.
Make sense?
Bryan

 

[Charles E]

. . . After the moment of exit, not one thing about the rifle or load or gun handling has any bearing on what that bullet is going to do.........it's all up to the bullet at that point. 100 yds, or 1000 yds, that bullet is on it's own. Bryan

Bryan, a little story. One day at Hawks Ridge Jim Borden & Dave Tooley were both in attendance. I was shooting my HG, which in some ways is like a PB rail gun -- no shoulder contact, you just catch it, even though it rides in sandbags.

I had developed the bad habit of catching it early, after about 1-2 inches of recoil, so as to be able to looks through the scope & see the bullet impact. Also wasn't shooting so good. Both Jim & Dave came up (separately) & remarked that yes, they knew the bullet had gone, but experience with PB (point-blank) rails showed you shouldn't catch them so soon. And that paralleled my own experience with a rail.

So the next day (match 2), I let the rifle come on back. To see, I just held my head farther back, so the scope came into focus after recoil.

The gun shot much better.

* * *

Lord, it seems to be winter again. Theories coming out of the woodwork. Data (& theories) are fine, as long as they lead to smaller, more consistent groups. I'm not much interested in any other kind of data.

 

[Boyd Allen]

Come on fellas. He comes on the board and says what looks in tune at 100 looks out of tune at 200, and because it doesn't jive with one theory of what is going on, his results are discounted. How about your theory is still a theory and not fully verified, and this data calls it into question. I might add that his results seem to be consistent with Varmint Al's work. I think that Alinwa is correct.

 

[John Kielly]

I suspect that we have the possibility of a number of circumstances that might have a bearing on performance & they aren't necessarily mutually exclusive.

1. There are zones or nodes where happenstance influences outcome. It is an accepted practice in centrefire benchrest to load towards the midpoint of these zones which happen to coincide the elevation of shots with variations in velocity that otherwise might be expected to cause elevation issues. Al speaks of 40 fps velocity variation & we (you) know from experience that some pretty wicked groups can be shot with such loads in this circumstance.
   
   
2. I shoot long distances (1000 to 1200 yards) under an arcane restrictive prescription & I know that because of the performance of projectiles in the transonic range, among other things, I can't rely on compensation alone to resolve elevation in my groups at all distances. Therefore, my first goal when tailoring a load is to achieve a velocity spread as low as possible, certainly never greater than 25 fps, with corresponding encouraging standard deviations, then tweak (tune) the barrel until the group size corrsponds with the expectation that these numbers give, It works for me & for quite a number of my counterparts in this particular sport in Australia. In one admittedly atypical case, I was able to convert a 100 yard MOA group into one of around ¼ MOA (10 shots in each case) & that tuner adjustment carried on right out to 1200 without any further fine tuning.
   
   
3. Finally, we have Gene Beggs' case, where he avers with some justification, if we believe Wilbur, that he can accommodate to the environment change that usually is managed by tweaking the load detail to detail.

John

 

[mike in co]

Come on fellas. He comes on the board and says what looks in tune at 100 looks out of tune at 200, and because it doesn't jive with one theory of what is going on, his results are discounted. How about your theory is still a theory and not fully verified, and this data calls it into question. I might add that his results seem to be consistent with Varmint Al's work. I think that Alinwa is correct.

ohhh and we are suppose to accept that the shooter made no errors, no change in conditions from 100 to 200......

sorry lots of possibilties WITHOUT CLAIMING gene is wrong.

right on the rude side.

mike in co

 

[Jerry Reisdorff]

I will re-shoot and re-verify my results for ya but I shot those groups one after the other with flags and after cooling of the barrel.

First I shot at 100 yds to get initial tune - 5 - 5 shot groups just like a match.

Then

I shot at 200 yds thinking it would be just wonderful - it wasn't -
Adjusted the tuner and the it shoot better groups.

Went back to 100 yds adj scope and groups good not great.

At FRGC I can place a target at 100yds and a 200rd target directly above and all one has to do is more up and adjust scope setting.

Scope is a New Lup 45X.

 

[Boyd Allen]

Mike,
You mean that I can't subscribe to a different theory than a friend without being considered rude? I was just pointing out what had happened in the course of an exchange between several posters. I value Gene's work, and consider his tuner to be an excellent and well thought out product. I just subscribe to a different theory as to what is going on when they work.

I think that Jerry brought us valuable information. I don't remember much being written about the sort of test that he has described. We are talking about cutting edge technology, and we may not have the how it works fully nailed down. Heck, if it has been otherwise, I would be having to change my theory of tuner operation, which could happen, if new, solid data were to make it obsolete.

 

[mike in co]

boyd,
you were using ONE set of data to discount a product. yes you can have your own opinion of how the world turns. your wording( to me) seemed to be more of discounting gene, than supporting your opinion.
no biggie at this point.
even with the latest post on the "test" we have no input on the AD..alttitude density change. look at the post on temp affect on n133 in charge weight and velocity.
i see lots of opportunites for change which whoud require a tunner adjustment.
mike in co

 

[Boyd Allen]

Mike,

I didn't say anything about any product. I experssed a difference of opinion on how tuners work, and about how readily information was discounted by some, that is all.

Boyd