bent barrels on airguns

[1377x]

i was talking with a local air gunsmith last week and he mentioned to me that a lot of the crosman barrels are bent and have to be tweeked to make them straight shooters.i was "called out" on the matter and told to provide proof.
heres the proof
i read a lot of different forums and see a common problem being posted about
the problem is running out of scope adjustment.
the scope and/or crown gets the blame
the berrels get recrowned.scopes get changed and yet they still run out of svope adjustment
if not running out of scope adjustmen they get pretty close to it.i have read may posts saying they have to go almost all the way to the right or all the way/close to all the way up you get my point .the scopes adjustments run out or nearly run out. canted mounting holes get the blame too
in springers its called droop if it wasnt a common problem then droop compensating scope rings wouldnt be sold by the masses they are.
what most people dont realize is the problem lays with the barrel,its not only a springer problem or related to one particular brand
if the barrels were tweeked on such guns then there wouldnt be a need for drop compensating scope rings.with tweeking such a barrel scope/sight adjustment wouldnt run out or nearly run out of adjustment.
i commonly see this with 2240's and 1377's .i cant say how many posts i read about this recently and here on the forum.people return there guns to the factory for replacement only to get another gun with the same issue
with my 1377's most of my open sights are adjusted all the way to the right thats the direction i commonly see,also.
you might get lucky and get one that doesnt need to be adjusted all the way right or all the way left
bds reported that his new bug out 2289 was shooting straight right out of the box no major adjustment had to be made for sight in.
lets see how many of the other 2289 bug outs are shooting straight without  having to move the sight left or right
if all barrels were straight and squared then the left and right windage adjustments would only be used when wind is a factor
sadly thats not the case.
and bent doesnt mean it has to be in a u or s shape the slightest undetactable bend will only be noticed during sight in
maybe a lathe would tell rolling a barrel on a flat surface would only be noticed a proffesional who actually looks for this stuff
just watch this video and you will know why the majority of our mass produced gun have "bent" barrels and why fx guns are so accuracte and you pay what you pay for quality.if crosman did this to their barrels instead of contacting an overseas company as we all know doesnt have a high standard qc dept,we would be paying a lot more for our crosmans
[youtube]https://www.youtube.com/watch?v=V_HTQwrTG6s#]https://www.youtube.com/watch?v=V_HTQwrTG6s#[/url]

[Motorhead]

For YEARS Robert Beeman of Beemans Precision Airguns offer a service called "SCOPE CORRECTION ANGLE" that was nothing more than a controlled upward arch bending of the barrel down it's length.
With some practice and common sense a mod one can do themselves to adjust parallax errors and alignment issues between receiver/scope mounting and barrels POI.

In the past 30 years air gunning have personally adjusted MANY this way.
To keep in context ... Has NOT effected accuracy what so ever OTHER THAN being to actually get optics and pellet to get to the same POI. 

[jdub]

I run into this a lot... not because of bent or droopy barrels but because I'm trying to sight a scope in at a close distance and the centerline of the scope is 1.25" to 1.5" *above* the centerline of the barrel.  I run out of adjustment and have to shim the scope *not* because the barrel is bent but because I have to make the scope centerline drop by 1.25" within 5 yards.   In effect I'm making the scope point down so its centerline crosses the path of the pellet at 5 yards.



The higher the scope is mounted and the closer the sight-in range--the bigger the problem.  Some of my springers do droop but if I sight them in at 20 yards I have enough travel in the scope to handle it.

However, this does *not* explain the windage problems that Ed mentioned.  If the scope is mounted correctly on the barrel then the windage of both should be in alignment.

[BDS]

There are a lot of issues at play with "bent" barrels or ones that "droop".

Bent does not neccesarily mean bent in a perfect plane in an up/down condition, they can also be off center from the breech or bending away from the breech, right/left or... even a combo of all the previous  Whoa! That's a lot to compensate for!

Add "cheap" scope mounts, dovetails that are not perfectly in-line with breech and barrel and... jeeez, what a mess!

It often takes some detective work to sort it all out but, I have always had the best luck with the barrel roll on a granite top or flat steel table top, followed by a fit check to breech and then dovetail or sight rail alignment to the other two components.

Here's a cool pic of a helix barrel FWB .177 target pistol that actually shot as well as it's straight barrel cousin, it was built to prove a point within FWB. Optically, it seems strange but, there are no pinch points and, the breech and sights and barrel crown/sight are in perfect alignment so there is no issue with sighting and shooting.

[ped]

it's not just a crosman problem i think most long barrels will be bent to a degree,as long as it's bent in the verticle plane i wouldn't worry about it(except if the bend was visible to the eye) as scopes can be shimmed
ped

[BDS]

it's not just a crosman problem i think most long barrels will be bent to a degree,as long as it's bent in the verticle plane i wouldn't worry about it(except if the bend was visible to the eye) as scopes can be shimmed
ped

Ya but, IMO shims are really a last resort and can't be too thick or one risks tweeking scope tubes and other nasty stuff happening?

[ped]

i use old 35mm film and haven't had a problem yet but i know what you mean about the possibility of bending scope tube
ped

[BDS]

Yup, that's about the limit or thickness of shim to use.

[YSYEO]

...
lets see how many of the other 2289 bug outs are shooting straight without  having to move the sight left or right
...

Mine's about 3/8 inch to the right at 20 feet with the rear sight still in the center.

[Graemevw]

I didnt have enough scope adjustment on my 2250. I did shim the rear of the scope a tiny bit, but the main problem was the barrel band was pulling the barrel down towards the air tube.
I put a thin shim under the barrel, inside the barrel band, and all was well again.

I guess a badly fitted barrel band could also push the barrel left or right?

[Motorhead]

I didnt have enough scope adjustment on my 2250. I did shim the rear of the scope a tiny bit, but the main problem was the barrel band was pulling the barrel down towards the air tube.
I put a thin shim under the barrel, inside the barrel band, and all was well again.

I guess a badly fitted barrel band could also push the barrel left or right?

In general, Crosman Benjamin with there semi floating barrels have VERY POOR barrel retention designs !!!
Sloppy and mis-fitting sums it up pretty well.
Thus WHY the aftermarket makes Better Breechs, Better Barrel bands etc ....

[Graemevw]

Indeed.

I already have a few steel breeches, but only stock barrel bands at the moment.

[breakfastchef]

The OP stated, "all of xmans guns are bent and have to be altered to make them straight shooters". That is a pretty all-encompassing comment that could lead folks to shun Crosman products. It also assumes that bends make a gun unable to shoot straight.

Here's a cool pic of a helix barrel FWB .177 target pistol that actually shot as well as it's straight barrel cousin, it was built to prove a point within FWB. Optically, it seems strange but, there are no pinch points and, the breech and sights and barrel crown/sight are in perfect alignment so there is no issue with sighting and shooting.

Brian, that pistol perfectly addresses why the OPs statment was fundamentally flawed. Barrels may often have slight bends or curvatures, BUT that does not mean they cannot shoot straight. And a diatribe about scopes running out of adjustment can be caused by a myriad of factors, not just the barrel.

[1377x]

my actual statement was just about all crosman barrels are bent and need altering to be straight shooters.there might be that one that doesnt need work but i cant see that either.if no work at all was done to the barrels, you would need the great wall to see where your pellet went in more cases than a few
the degree to which these barrels are bent is not the point.a bent barrel is the point.sights not scopes show that a barrel needs to be altered/ bent in a direction to make it stay with in sight adjustment parameters most of the time.there is a way to see how bent a barrel is and thats the fx does it in the video
truth be told all barrels are bent,not just air guns. thats why they need to be altered to be straight shooters.all barrels made need a degree of work done to them.some extremely bad ones make it through the high standards of crosmans qc and can either get worked on some more or sent back to the factory for replacement and then you hope to get a sraight one
the picture of the twisted barrel has the end straight, if it wasnt it would be shooting in the direction of the bend not the target.they had to alter the bend to make it shoot straight the picture is proof of that also anly about 1" but less than two inches needs to be straght and rifled
scopes for a number of reasons can need adjustment loose lens bumped scope height etc,open sights are different the only lens that comes into play is the lens of your eye
from what i have heard crosman barrels are hammer forged.there is no way a hammer forged barrel is not going to need some work to shoot straight.
fx is a high end barrel and costs what it does because of the amount of work put into it straightening it out.less than 2 inches is rifled in an fx barrel
only a very small amount needs to be rifled.the amount of rifling is not the point
my point is the barrels are bent to whay degree they are bent is not in question.if crosman went through the degree of craftmanship ship fx does we would be paying more than $10 for a barrel.even an lw barrel is more expensive than a regular crosman barrel
why does a lw 10" .177 barrel cost more than a 14-24 inch crosman .177 or .22.because of the amount of work that goes into a barrel
i guess its to much for some people to fathom that these barrels or any barrels need work to become straight shooter

[BDS]

Whoa pardner! 

Yes, I have had "bent" barrels but.. I have also checked the TIR (total inidcated runout) on many others and two of my Crosman guns dialed in at .001" or less across 10 and 12 inch lengths and crown to breech paralellism was just as good.

Barrel making (gun drilling) removes a lot of material and the steel can relax or let loose, that's why most barrels are soft on the Rockwell scale of hardness so that the steel can relax and memory can take over. It's more of an art than science and mass production is pretty unforgiving, so Cos. like LW do TIR checks and other QC stuff to eliminate much of these issues.