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"What Happened to Me" by Josh3rd (long post)

September 26 2017 at 11:02 AM

Hector Medina  (Login HectorMedina)
YF

Josh;

Sorry for the late reply, but with two little ones and a ton of stuff going on, plus the fact that there was info all over the place, I had to take a little while to mull all things over.

So, let's start with the gun:

Pro Sports are elegant guns that CAN perform very well at their intended power level: 12 ft-lbs.
The architecture of the gun (side rails where the mechanisms are mounted mounting then onto the stock) makes for VERY peculiar stresses and shifts. This is not unique to the ProSport, it also happens to SMLE's (all Mk's). There are ways to bed these guns, but it is not the way factories do it.
So, my first piece of advice (that you have already gotten) is drop down the power to 12 ft-lbs. MAX 13. No more. There are several ways to do it, PERSONALLY I do NOT go for "skinny" (sleeved) pistons simply because they require equally skinny springs, and since internal stresses in the spring steel go with the CUBE of the OD, it makes little sense increasing the internal stresses of the springs when they are already pretty close to their limit.
A short stroke piston with a maxed out (OD) spring in a custom guide would be the way I would prefer to do it.
Make sure the stock is well finished INSIDE AND OUT. And test, under different environmental conditions, how the gun performs.

Now, the scope:
Hawke scopes are not too reliable. You need to work on it to learn its idiosyncrasies. Theoretically, your scope's reticle should be "true" at 10X (or so the website says), but I have found in actual scopes that that is not ALWAYS, EXACTLY the case.
So, set up a mil-confidence target (anything that is marked in inches) at 27 yards 2 feet and 4 inches and make sure you verify that your mils are true miliradians.
IF you are not interested in using the metric system, then check that at 12X you are getting IPHF (Inch per Hundred Feet) between mil-dots.
While you are at it, you should also measure what is your true Click Value (set the scope at a point in the ruler or other marked object you are using) and dial in 40 clicks, then see where the CH's are at. Note it, and now you can divide the whole distance by 40 to know the average value of each click (not too useful for AAFTAHFT, but useful for sighting in with the least number of shots).
IF you can, do these tests at different SCOPE temperatures (you will need two strip thermometers: a beer brewing one and a reptarium one glued to the main tube of the scope, just make sure that you have space to use the rings), you will gain much information.

Now the pellet:
EACH barrel will prefer one specific pellet. WHY? all the industry is working on that and has been for the last 25 years without any real answer. It is just a fact.
It is also a fact that the final SHAPE of the pellet is given by a combination of the powerplant pressure delivery and the rifling (including the choke). Since the shape defines the drag (real, not theoretical) and the drag is SIMULATED in the ballistic software using a scale factor we call Ballistic Coefficient, the BC is dependent on the tune, the barrel and the batch of the pellet (each batch may use a SLIGHTLY different metallurgy and/or dies and therefore the final shape will depend on how much the pellet gets deformed, or not, when shot), your trajectory WILL change as the pressure delivered to the skirt by the powerplant changes (DO NOTE I am saying Powerplant, so this applies to PCP's also).
H&N's are consistent pellets, BUT as much as I like the H&N guys (we've worked closely on a few projects), nobody's "purfect". And even if all the factors in the pellet are the same, changing venues (altitude, temperature, humidity) WILL change the pressure curve delivered by your powerplant to the pellet.
Last, but not least is the fact that precession, nutation and yaw are the most detrimental to a good BC. A lighter pellet that flies true will have a substantially higher BC than a heavy pellet that wobbles.
SOMETIMES, you can establish if your pellets wobble by setting up a powerful/laser flashlight under the gun at sunset and watching how the pellet flies to the target by watching the reflection on the skirt.
A high speed camera affixed to the scope can also help, but not everyone has one.

Now the shooter:
If you changed your attire, most probably, your POI will change. A jacket, even a thin one makes a difference when it is on or when it is off.
Gloves change the POI.
If you use a baseball cap, it might change your POI if the visor touches the scope while the gun is recoiling.
If your level of hydration changes, the eye, that is almost 98% water, will change, and with this the focus and the acuity.
Sitting differently will change your POI, how you rest your gun in the sticks can also change POI.
You need to test AND shoot in EXACTLY the same configuration.
You also need to test elevated (inclined) and downhill (declined) shots. The angle of the barrel will change your POI.

Now, IF EVERYTHING ABOVE is constant/known, now you can deal with the environment.
Wind is the pellet's Nemesis. Pellets are (like all flange-stabilized projectiles), extremely sensitive to air flows.
Wind from the front will make you hit low. Wind from the rear will "float" your pellets along and yield a higher POI.
Wind from the left will not only make your pellet drift to the right, it will also make it climb a little.
HOW MUCH these effects change YOUR POI is something for you to determine.
Ranging from the shadow to the light will change your ranging
Ranging in bright light will give you different results as ranging with an overcast sky.
IMHE, putting all the marks on the scope in one day is impossible to do accurately. You are better off putting in pencil marks and then checking along the week at different times to see how PRECISE (true to true value), your ranging is.
Same goes for the trajectory. Do it and then check it again and again under different conditions.

I'm sure I am forgetting a few things, LOL!

Springers are peculiar beasties.
And yet, they are most satisfying.

Take your time, enjoy the trip.

HTH





HM

 
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AuthorReply

AngliaUSA
(Login AngliaUSA)
YF12

Great reply - the Airgun GURU has spoken !

September 26 2017, 12:16 PM 

Pretty much applies to all airguns but mostly Springers .. even Whiscombes.

Thanx for the detailed reply Hector .. you da man !

 
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Ron
(Login rj222)
YC

What is a Whiscombes?

October 10 2017, 3:37 PM 

"A woulda got a higher score if I hadn't missed so many"

Ron @ CASA

 
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Boomer
(Login Boomer75)
YF

Figures!!!!!!!

September 26 2017, 3:06 PM 

As I get ready to press "post", I check the page and see that you posted EXACTLY what I was going to send. Now I have to check my pc to see how you got it word for word what I was going to say... happy.gif

Hope you are laughing now Hector. happy.gif

Thanks,
Boomer
"I am not addicted...I can quit anytime I want...I just don't want to..."

[linked image]http://www.bagaclub.com/

 
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Ron Robinson
(Login compressive)
YC

Apparently,

September 26 2017, 3:32 PM 

You've located your long-lost evil twin, Boomer. One question though. Which one of you is handsome one?

 
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Boomer
(Login Boomer75)
YF

Hector got all the looks, I have to be 100% honest!!!!

September 26 2017, 7:48 PM 

I got the voice for radio
Hector got the face for TV!!!!

Boomer
"I am not addicted...I can quit anytime I want...I just don't want to..."

[linked image]http://www.bagaclub.com/

 
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K
(Login Knobs)
YC

Do you sometimes wish....

September 27 2017, 8:10 AM 

...that you were just born rich instead of so damn intelligent & good looking?

LOL

K

 
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Boomer
(Login Boomer75)
YF

one could only wish my friend....one could only wish......n/t...

September 28 2017, 10:01 AM 

Boomer
"I am not addicted...I can quit anytime I want...I just don't want to..."

[linked image]http://www.bagaclub.com/

 
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Josh3rd
(Login josh3rd)
YF12

Lol, good one. NT

September 27 2017, 5:51 AM 


 
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Twentycal1
(Login Twentycal1)
YF12

This to certify that I read and understood every word Hector said and then....

September 29 2017, 7:08 AM 

Went bowling!

 
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Paul Porch
(Login paulporch)
YF12

Hector, you did not mention pellet spin rate and the effects wind will have on

September 26 2017, 4:45 PM 

Faster or slower rates.....

 
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Bill Day
(Login dayjd2)
YF12

Paul, Don't we have enough to work with ...............

September 26 2017, 5:07 PM 

Without adding more brain freezers. I'm thinking he was addressing Mr. Springer for our PCP's aren't quite as edgy quite so often. Don't misunderstand me and as you already know PCP's can be finicky sometimes too but Mr. Springer wins the Chicken dinner!


    
This message has been edited by dayjd2 on Sep 26, 2017 5:08 PM


 
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Paul Porch
(Login paulporch)
YF12

Oh yeah he does......! Just had an in depth pellet spin speed discussion. At the PA Cup

September 26 2017, 5:59 PM 

With Manolo from PR Chris, Pedro and pellet guru Tom Holland. Manolo made some interesting points on the subject.

Of course we were also steadying downing some adult beverages and some factors escape me now....lol

 
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Griff C
(Login GriffC)
YF12

Whew

September 26 2017, 7:43 PM 

I may need to get back to shooting tin cans off a fence post.

 
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SteveV
(Login stevevines)
YC

Right there with you bro' ....nt

September 27 2017, 6:42 PM 


 
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Josh3rd
(Login josh3rd)
YF12

Man i can't wait till tomorrow.

September 27 2017, 12:02 AM 

Hector that is a lot to take in. Guess that's why you're a champion. Now when you said do the 40 clicks, is that at 10 or 12 power and is it at 27yds 2 feet and 4 inches or at 100 feet? And what am I distance am I dividing by 40? I'll have more questions for you by tomorrow evening. Thanks for your help.

 
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nced
(Login SpringerEd)
YF12

BRAVO!!!!! Most excellent reply!

September 27 2017, 10:35 AM 

Mentioned in other posts, the gun didn't have a shifting poi before it was sent to PA for a de-twang. This (to me) points to a botched tune that seems to has only addressed "spring twang".

Anywhoo.....a most excellent detailed response! I especially relate to "putting all the marks on the scope" comments. Currently I have marks on the AO of my 5-15x50 Hawke Panorama that were put there a couple days ago shooting at my practice lane. Well, last night I was checking out my "near zero mark" upstairs at 18 yards with a lighted target and found that the "near zero mark" on the AO didn't line up with the pointer like it did 2 days ago. I'm blaming most of this on 70 year old eyes that don't seem to focus the same from day to day!

 
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Héctor Medina
(Login HectorMedina)
YF

A little "on the fly "

September 27 2017, 1:06 PM 

Thanks for all your kind words.

What I wrote is just the results of a few years of careful observations and notes.
I have been blessed with the opportunity to dedicate myself to this full time, until becoming a stay at home Dad, LOL! Thanks should really go to Veronika, that made it all possible.

Anyway, short comments
Boomer is too modest, you should see the looks he gets from waitresses at the Texas Roadhouse in New Philadelphia. wink.gif

Paul is partially right in that rifling rates (twists) can define whether a pellet wobbles in flight or not, but in my experiments, and I am right now in the final stages of a very long research project that has taken over 4 years, there are other aspects that are as important, if not more.
Manolo uses an Anschütz barrel, so quality of manufacturing is a given there, he also specced the internal dimensions of the barrel for a pellet. So when he shoots these pellets, he has good results, but his barrels are not dramatically more "forgiving" of batch differences than others.

We need to remember that wind drift is proportional to pellet's velocity LOSS. And that is a function of drag, which in turn gets its worse boost from wobble.
A pellet that "goes to sleep" (meaning that it's turning in its own axis without any wobble) will drift much less than a pellet that does wobble, even slightly.
In BR and LR circles barrels that are capable of precisely and accurately putting to sleep the projectiles used are called "hummers". And within the realm of cilindroconical bullets, the factors that are conducive to this are rather well known.
Not so in the pellet world.
And there are two reasons for that, sort of like a push-pull toy.
The VASTLY PREDOMINANT twist rate for pellet barrels is in the region of 1/16". Partly inheritance of the old days of using RF barrels for Airguns.
So, most pellet manufacturers strive to obtain the best results out of these typical barrels.
And so, we perpetuate the situation where "natural selection" tends to ensure that the best probability of high accuracy comes from the established twist with the established pellet shapes.
Until recently, that H&N decided to "rescue" the efforts made by the deceased "Defiant/Prometheus" line in what is now called the "Sniper" line, we had not seen an innovative pellet shape since Sheridan's Bantams.

Again it's a question of minimizing the wobbles and given the extremely complex shapes of pellets we are still some time away from final results. But we are advancing.

Josh.- 40 clicks are not magnification dependent. Unless you want to measure the subtension (angle) instead of the distance (inches) between aimpoints before and after the 40 clicks.

If you measure the distance (inches) with a target placed at 95.51 yards, you will be measuring MOA's.
If you measure inches at 100 yards you will be measuring "shooter's MOA" or IPHY's.

PERSONALLY, I would suggest you measure the number of clicks per YOUR dots. As it is this combined number what will be most useful to YOUR method of shooting every distance possible.
It's not what I would do because having made PP-Calc, I tend to rely on it for establishing my numbers for each venue.

HTH


Thanks again, keep well and shoot straight!



HM

 
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dan_house
(Login dan_house)
YC

Awesome advice!!!

September 28 2017, 3:01 PM 

can only add one thing: be darned absolutely sure of your range from scope to target.

Ive setup several times using a hand truck with the target taped to it, and just roll it back and forth to the next distance to set a number for..... that part worked great, helped reduce the time and effort to do so......

then a couple years later, happen to walk past the hand truck setting on the level garage floor and noticed its angled BACK off vertical a few degrees (guessing so it doesn't tip your load off the front).... while its only a about 3 inches tipped back, I had been measuring from the bottom of the truck. SO Im off now by .25 feet...

That got me to examining every part of the setup process..... and I noticed a couple of other things......

My 200 foot tape measure would "bow" in the slightest breeze, meaning it measures shorter, and the flat plane of a field I do this on has a slight downhill to it, making it correct to the tape numbers, but shorter thru the air. Add them up and Im now off over a foot...... Little things add up quickly........





    
This message has been edited by dan_house on Sep 28, 2017 3:03 PM


 
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Jerry
(Login JCTX)
YF12

more about pellets, and a couple of suggestions

September 29 2017, 8:13 AM 

Josh,

You're getting a lot of advice from some very experienced (and expert) airgunners.

After reading this and other threads, I see you are listening and working to get a solution.

And for disclosure, I'm a field target shooter myself, and had some similar head-banging concerns about my shooting and my equipment. One of the great things about my airgun experience was the idea for a product called Pelletgage that can easily check the head diameter of pellets. I have sold a lot of them to shooters worldwide, and have numerous reports from users who found and solved issues with their pellets. As Hector points out, they can vary. Most shooters seem to find a brand, weight, and type of pellet that works well, and stick with that. In my case, the JSB (or Air Arms) pellets are the go-to. H&N are popular, as well. But there are cases where a lot (or a tin) can have enough variance to be a problem, and that variance can produce the kind of hard-to-explain results you describe.

Here is a BLOG post by a very serious varmint hunter, Cliff Tharp. Cliff uses high power PCP rifles to shoot prairie dogs at long range. His equipment, skills, and experience in this type of shooting are up there with the very best. Early on, Cliff purchased a Pelletgage, and he wrote about what he found.

https://web.archive.org/web/20160805114539http://varmintair.typepad.com:80/varmintairs_blog/2015/06/okay-lets-get-real-about-head-sizes-and-pellet-weights.html

If you're shooting FT, ask to borrow a Pelletgage, and check that tin of FTT's. My suggestion is that the tin should have a mean size with a two sigma variance with +/- 0.01 mm limits. For a mean size of 4.52 mm (as an example), 95% would be found to have diameters of 4.51-4.53. Also, doing a sampling and finding the mean diameter of the pellets that shoot well in your gun lets you know which size to buy in future. If you sample 50 pcs from a tin of 500, no more than one should be more than 0.01 mm from the mean size. Note also, the mean size could be 0.02 mm or more from the nominal size you think you have!

You seem to have a capable rifle, and I will bet that if you keep plugging away, the problems will be solved. I switched to a PCP rifle, and it still took more than a year of shooting it, making adjustments, etc before I could compete in field target.

Here are some suggestions (some you already heard) based on my experience:

1) get that chronograph, and use it to see that you are getting a consistent velocity. If you don't have that, accuracy will be impossible.
2) avoid drinking any caffeine for hours before shooting.
3) a stable scope mount can be hard to achieve - make sure that your mounts are secure, but also that they don't impart any pressure on the scope tube. This amplifies the effect of temp changes. Even good mounts can have a latent torque or bending moment that shift the scope enough to matter. You might re-mount, and be careful to tighten carefully and evenly. In some cases, going to a quality one piece mount would help. Some people even lap the scopel

good luck!


    
This message has been edited by JCTX on Sep 29, 2017 8:19 AM


 
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