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barrel droop.....does it even exist?

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Yogi:

--- Quote from: Deerstalker on October 14, 2020, 07:36:58 PM ---
--- Quote from: wolverine on September 19, 2020, 02:04:07 PM ---i thought pellets and bullets rose from the from the muzzle to an apex and then began to drop, making the trajectory an arc and giving 2 poa/poi.

--- End quote ---
Another pic on pellet trajectory.


--- End quote ---

Yes but when you initially set up a scope you have no idea if you are at the first zero or the second one.  2 zero's just make everything more difficult for target shooting.  For hunting they are fine.

-Y

Methuselah:
I know this is an old thread, but the airgun gate has ten times the traffic, so it doesn't seem like such a big sin...

One thing not mentioned about droop and the effect on the scope is that it isn't necessarily going to require money to be spent correcting a perceived problem. I say perceived because there are work-arounds.

For a situation where droop isn't severe maybe the scope rings can be shimmed. I've used cut pieces of tin cans between layers of electrical tape but you could use friction tape I suppose.

The easiest "fix" is what one prominent user has advocated several times, bend the barrel. He's shown doing with a tree fork, and home made fixture too. He also posted a pic of a factory using a giant press to do it. I've made a fixture and done it, corrections are in 1/1000'ths of an inch and it doesn't effect accuracy (there's a pic here of a German made gun with the barrel in a loop that was reported to shoot accurately).

I think I watched a youtube video of barrel bending by tapping the barrel on a log too...

lefteyeshot:
I've read gunsmith back in the day who made dueling pistols used heat and tapping with a hammer to make the guns POA and POI the same.

I never used shims in the scope rings. If a droop mount didn't fix it I bent it. I have two droop mounts in my tool box. One was on my Diana 350 PC. When I started using heavier pellets I had to remove it. One I had on a gun backwards cause the gun shot to high. Don't remember the outcome. Sometimes I think the scopes are the culprit. I've bent a few that were shoot too far right or left.

Most guns I've bent the barrel were old Chinese guns. Had a Hatsan 135 come bent about 6 inches from the muzzle. Last time I paid for a pre-shipping gun test. Using my jig I put a block where it was bent and one each a few inches before and after the bend. Worked okay.

Madd Hatter:

--- Quote from: nced on September 19, 2020, 05:06:25 PM ---
--- Quote from: Joey on September 19, 2020, 10:26:52 AM ---Why would several excellent companies, making quality spring piston rifles all have "problems" with barrel droop.  If you can make a rifle capable of one hole groups out to 25 yards or so, why would barrel droop be a problem?

I've been thinking about this for years and I think I have an answer.  A well made rifle puts the centerline of the rifle bore and the centerline of the scope( when the scope is adjusted at the center of it's range) pretty much parralel.  If that's true, the rifle would NEVER shoot to point of aim.  The bullet starts dropping from it's centerline as soon as it leaves the muzzle.  With an airgun, that drop amounts to several inches at , say 50 yards.  Well, the pellet starts out about 1 1/2" below the centerline of the scope and at 50 yards could be maybe 6" low.  That's a LOT for a scope adjustment to make up.  Back when iron sights were more popular, they could be built to copensate for that easier because they were closer to the centerline of the bore.  Building a rear sight a bit higher and with more adjustment is a piece of cake for a good gun maker. 

A fast, centerfire rifle bullet drops WAY less than a pellet, and is normally sighted in at much longer distances.  This next bit is all nominal for explanation purposes.  A 1 degree adjustment in the scope elevation would put the POA and POI at the same point because of the flatter trajectory of the faster rifle.   Comparitively, a pellet has a rainbow trajectory that needs a LOT of adjustment to tilt the ever-falling pellet up to get to the POA. 

A pretty, computer designed picture here would certainly help me explain my concept.  Not in my skill set.



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Perhaps "barrel droop" isn't an issue for the majority of airgunners outside the USA that use "iron sights". I've read that some makers (such as Diana) "design in" droop to accommodate the tall front sights with the interchangeable inserts (however I don't know if I completely believe this story). If the droop issue was only related to "manufacturing tolerances" then there would be Dianas with both "snoop and droop". Since droop is the "common issue" I do tend to believe that droop is "designed in" for whatever reason..........

I've never handles a Diana "fixed barrel" but I just finished looking a a lot of RWS54 pics and it certainly seems that the barrels are "drooping" relative to the receiver.

Anywhoo....I do know that "droop" is a reality for guns such as the RWS34 that I looked at decades ago at an airgun show. The droop with the brand new RWS34 was so pronounced that it was easily seen by eye without the need for a straight edge as a reference. Rather than "fix a droop issue" RWS offers the "Lock Down mount" with .025" elevation compensates for barrel droop...........
https://www.pyramydair.com/product/rws-lock-down-1-pc-mount-w-1-rings-11mm-dovetail-barrel-droop?a=2406

LOL......I bought one of these mounts and used it on my HW95 resulting a poi 4" above the poa at only 18 yards!

   

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I can tell you that my Diana 48 which IS a fixed barrel droops. I have to use a .005 shim under the rear scope mount. Been that way for the 30+ years I've owned it. My hatsan 125 sniper has no droop.

Yogi:

--- Quote from: Joey on September 19, 2020, 10:26:52 AM ---Why would several excellent companies, making quality spring piston rifles all have "problems" with barrel droop.  If you can make a rifle capable of one hole groups out to 25 yards or so, why would barrel droop be a problem?

I've been thinking about this for years and I think I have an answer.  A well made rifle puts the centerline of the rifle bore and the centerline of the scope( when the scope is adjusted at the center of it's range) pretty much parralel.  If that's true, the rifle would NEVER shoot to point of aim.  The bullet starts dropping from it's centerline as soon as it leaves the muzzle.  With an airgun, that drop amounts to several inches at , say 50 yards.  Well, the pellet starts out about 1 1/2" below the centerline of the scope and at 50 yards could be maybe 6" low.  That's a LOT for a scope adjustment to make up.  Back when iron sights were more popular, they could be built to copensate for that easier because they were closer to the centerline of the bore.  Building a rear sight a bit higher and with more adjustment is a piece of cake for a good gun maker. 

A fast, centerfire rifle bullet drops WAY less than a pellet, and is normally sighted in at much longer distances.  This next bit is all nominal for explanation purposes.  A 1 degree adjustment in the scope elevation would put the POA and POI at the same point because of the flatter trajectory of the faster rifle.   Comparitively, a pellet has a rainbow trajectory that needs a LOT of adjustment to tilt the ever-falling pellet up to get to the POA. 

A pretty, computer designed picture here would certainly help me explain my concept.  Not in my skill set.

--- End quote ---

Joey,

If you have a gun with peep sights that are both mounted on the barrel, then barral droop is a non-factor.  That is how most European guns are sold.  And until recently that is how most Europeans used there guns.  So NO barrel droop with open sights mounted on the barrel!

-Y

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