Wednesday, July 30, 2008

Straightening barrels

Guest blogger
Rick Klages had an unfortunate accident that bent the barrel of his R9 Goldfinger air rifle. He asked me for advice and was surprised when I told him to just bend it back. This is his story.

If you'd like to write a post for this blog, please email me at blogger@pyramydair.com.

Bloggers must be proficient in the simple html that Blogger software uses, know how to take clear photos and size them for the internet (if their post requires them), and they must use proper English. We will edit each submission, but we won't work on any submission that contains gross misspellings and/or grammatical errors.

Straightening barrels
by Rick Klages


Beeman R9 Goldfinger


It's an overcast July 4th morning, and I'm working on adapting my artillery hold to a prone position. Being humid and hot outside has led me to perspire, and laying in the grass has made my hands slick. Compound this with my failure to remove my wedding band (titanium), and we have all the makings of a classic breakbarrel stupident. I was cocking my R9 Goldfinger while laying on my left side and palming the muzzlebrake instead of firmly grabbing it, when my hand slipped off. I was very near the end of the cocking stroke when the barrel snapped closed with nearly the full force of the mainspring.


Not all bent barrels are as obvious as this R1. Anytime a breakbarrel snaps shut by itself, the barrel will bend upward at the junction of the baseblock. An average adult male should be able to bend it straight again following the directions Rick mentions below.


So, I picked myself up and started to take stock of what just happened. Ok, no broken wood, good. Everything else looks normal. But when I took a few offhand shots at 50', I realized there was a problem. The point of impact had moved 4" upward. Now what do I do? I could call Beeman, but this was a holiday! Tomorrow was Saturday, and there was no way I could wait until Monday to work out my dilemma. The barrel doesn't look bent. So, I asked B.B. what he thought. This was what he wrote back to me:

Your barrel is bent. It happens every time a breakbarrel slams shut. You are lucky the stock didn't crack, too, as that often happens. You have to straighten the barrel again. A friend of mine does it all the time and he says the barrel will straighten easily, but will resist going past straight. You should be able to see the bend, which is located at the front of the base block, by looking through the barrel.

I was a bit incredulous at the suggestion I could simply bend it back, but B.B.’s instructions were simple:

Straighten the barrel by bending it in the opposite direction. It's best to take the action out of the stock for this and support the action on a solid table. Muscle power, alone, is all you need to straighten an airgun barrel. As you bend it back, you can feel the steel "giving." It sort of shudders as it returns to straight. Once straight, though, it does not want to bend farther, so the resistance increases.

I decided to give it a try. I removed the scope and took the action out of the stock. Using my sturdy kitchen table and a large, clean terrycloth towel as padding, I broke open the action. As I placed the compression tube/receiver on the towel, I applied downward pressure on the barrel. The spring cocking lever bottomed out in the action and the next thing I felt was a slight shudder. I used a fair amount of force. Pushing harder resulted in no other sensation of movement. Even though the rifle has a safety that automatically engages upon cocking, I made sure to keep clear of the naked trigger. It may be prudent to remove trigger units, if possible.

I then reassembled my R9. So how did it go? Here is my reply to B.B. after all was said and done:

It worked! I wouldn't have believed it really. I didn't think I could bend a steel rifle barrel without a press and since I don't have Superman on speed dial I was skeptical. So I tried it. I will now add "Bends steel rifle barrels with bare hands" to my resume. Best of all my R9 is back to normal. Thanks for the advice.

40 Comments:

At July 30, 2008 6:52 AM, Anonymous JP said...

Question: is a breakbarrel rifle solid, I mean, is the barrel solid steel like a firearm, or is it a barrel tube/sleeve arrangement like the average air rifle? is there ever a problem of barrel bend just from normal cocking? JP

 
At July 30, 2008 7:21 AM, Blogger Il Bruce said...

Well done.

I too have wondered about barrels bending during cocking, but again I assume that the engineers know what they are doing. I was mildly surprised the first time I read about this barrel bending.

I have returned steel bike frames to their original geometry by bending. I have always been a bit nervous about it though. My first attempt resulted in the stays snapping off of a nice Reynolds 531 tubed Dawes racing bike. We let the shop owner relay the news to the owner. The failure was due to poor brazing not the material.

Steel really is a remarkable material and despite fashion 5/6 of my bikes are made of it. Is there any trend away from steel for gun barrels?

 
At July 30, 2008 7:31 AM, Anonymous Anonymous said...

hi BB, sorry about being so far off subject, but was it the hammer weight that gave you the high fps numbers when you tested the condor with the micro meter tank? ive been trying to find out what a standard talon in .177 cal. with the micro tank would do. it was easy to make and educated guest, but then i was reminded of the hammer weight difference, anybody have any fps numbers or fpe, thanks Allan

 
At July 30, 2008 7:40 AM, Blogger B.B. Pelletier said...

Allan,

That was a factory striker in an early gun. The weight would be around 53 grams, I believe. But I think that info is meaningless here.

The MM valve is grossly overpowered by the Condor. It can only open so far and stay open so long and the Condor opens it with more energy than required. In other words, a heavier striker shouldn't make a difference.

B.B.

 
At July 30, 2008 8:26 AM, Anonymous Anonymous said...

Nice post Rick! Glad to hear that you were able to fix your barrel and that all is not lost if one has a "stupident".

Al in CT

 
At July 30, 2008 9:03 AM, Anonymous twotalon said...

Allan
With a .177 Talon, you can expect somewhere in the 800's with a medium weight pellet. With the SS you get somewhere in the low to mid 700's with medium weight pellets.
Hammer weight has no effect. Power wheel adjustment has no effect.
The micro dumps a fixed volume of air at the remaining tank pressure no matter what you do.
Velocity will slowly decrease as you use up air.
You will get what you get, and that's it.
twotalon

 
At July 30, 2008 9:30 AM, Anonymous Anonymous said...

Good morning, B.B;

Is there going to be further articles about the Condor? I am mostly interested in the accuracy potential with heavy(25+ grain) pellets in .22 cal.

Thanks for your time; Gary L.

 
At July 30, 2008 9:30 AM, Anonymous Anonymous said...

BB,
If you had barrel droop, would this work if you did it in small doses over time(cocking it ti 15degrees, then letting it go).
Shadow express dude

 
At July 30, 2008 9:38 AM, Blogger B.B. Pelletier said...

Gary,

I didn't have plans to test the Condor any more. I can tell you that with 28-grain Eun Jin pellets it gets between 1 and 1.25 inches at 50 yards on most days. An occasional group will be smaller than an inch. The Kodiak works much better in the Condor's Lothar Walther barrel.

B.B.

 
At July 30, 2008 9:39 AM, Blogger B.B. Pelletier said...

Shadow express dude,

Because the barrel does not want to bend easily from straight, I don't think this is a good option.

I have never heard of it, but maybe someone has?

B.B.

 
At July 30, 2008 10:10 AM, Blogger B.B. Pelletier said...

JP,

Some barrels are solid steel like the one in this report, and others are a liner inside a jacket, like a Gamo Whisper.

B.B.

 
At July 30, 2008 10:12 AM, Blogger B.B. Pelletier said...

Bruce,

There is a trend away from solid steel barrels because of the cost. It's much easier to pull a rifling button through a thin steel tube than through a thick one. Look at Gamo and all their plastic-sheathed barrels.

B.B.

 
At July 30, 2008 10:33 AM, Blogger Brody said...

B.B.,
God news. I have finally selected a camera. Its a Nikon CoolPix L18. It is $140 at my local store that has it. I am going to try and get it this weekend. So i will post a couple pics with it next week.
See ya,
Brody

 
At July 30, 2008 11:47 AM, Blogger Rick said...

I've found that if you want to measure HOW STRAIGHT YOUr BARREL IS, place a carpenters square on top of the block where rear iron sight sits. check that the rear of barrel and front of the barrel are completely parallel by using a dial caliper(inside measure part) and slide it between the square and barrel all the way down, noting any change in gap. just my two cents, and thank you for your blog rick.
cheers

 
At July 30, 2008 12:03 PM, Anonymous Anonymous said...

B.B. and Rick,

Yes, I was wondering about this episode when it first appeared. I'm surprised that one could bend a steel barrel with bare hands, but obviously it's true. Well-done, Rick. What still puzzles me though is how to do it with the necessary precision. Can you be sure that you are straightening the barrel in the exact same plane of bending without the teeny-tiniest degree of variation? It seems like even the smallest deviation could have a large effect on the accuracy of a precision rifle. When I look down the bore of my Savage 10Fp, I see a perfect geometry of spirals from the rifling grooves, and it's hard to believe that a human being could reproduce that precision with bare hands. How can you be sure?

I have a little repair question of my own on the further foibles of the B30. While blasting away last night, I was interrupted by a large black object hitting the floor. This turned out to be the adjustable front sight which had worked loose and fallen off. The sight fastens onto its ramp with a Phillips screw which is loosened to allow the sight to slide back and forth and tightened to hold it in place. I was right in there with my Phillips screwdriver, but I found that the screw was frozen in the loosened position. The sight slid onto the ramp easily enough, but no amount of force could budge the screw one way or the other. The opposite side of the screw from the head seems to have a small ding if that makes a difference although I don't see how that would affect the rotation of the screw. I shot hundreds of rounds through the gun with open sights and they were steady as a rock, so the front sight was working for awhile. Any ideas what happened here, or more importantly how to fix it? I sprayed Ballistol on the screw hoping to loosen it but with no effect.

Otherwise, in spite of the signs of shoddy workmanship, the B30 is getting even more accurate. This is a weird rifle.

Matt61

 
At July 30, 2008 12:07 PM, Anonymous Anonymous said...

Rick,

Are you shooting prone without a sling? I don't know if that's your rifle in the picture, but I don't see any sling attachments. I've heard of shooting in the unsupported prone but have not been able to make it work; the gun moves all over the place. And don't you find the prone position to be a hassle with the breakbarrel?

Matt61

 
At July 30, 2008 12:08 PM, Anonymous Vince said...

BB, I have a .22 cal TF89 barrel (mounted on a Walther Force 1000) that shot hard left, even after I straightened the barrel (it was initially bent to the left). Consistent, but about 4" off at 10 yards with the windage adjusted right as far as it will go.

I actually bent the barrel near the muzzle to compensate for this. I did it near the muzzle because I needed a certain exit angle - and if I bent the barrel from the breech end the front sight would have moved so much the POA would have moved almost as much as the POI.

It looks goofy as all get-out... sighting down the barrel you can actually see it hook to the right, and you can see the same thing if you look down the bore. But it certainly shoots well enough - at 10 yards or at 60. I would have thought that doing this would negatively effect SOME aspect of its shooting behavior, but it doesn't seem to have done so.

Based on this, I suspect that barrel bending COULD be used to fix Diana barrel droop without degrading the gun's performance.

 
At July 30, 2008 12:31 PM, Blogger B.B. Pelletier said...

Matt61,

You need to use an impact driver on that screw. Back in the 1960s, anyone who owned a Honda motorcycle also owned an impact driver, because the valve cover screws would sieze, due to head warpage.

Don't bugger that screw with a screwdriver - borrow an impact driver.

B.B.

 
At July 30, 2008 1:05 PM, Anonymous Anonymous said...

B.B.

Thanks, I'm off to Ace Hardware to get an impact driver or see if they will loosen the screw for me.

On the subject of straightening, I know that there is a such a thing as an arrow straightener. I wonder if the same device or principle could be used to straighten barrels. I'm glad to see that PA has gotten into the business of selling archery equipment and am enormously pleased at the arrow case I picked up from them.

Matt61

 
At July 30, 2008 2:04 PM, Blogger B.B. Pelletier said...

Matt61,

There is a barrel-straightening press, but it isn't needed in this situation. The barrel was bent by force and will only straighten to its original shape. It would take much greater force to go beyond that shape.

B.B.

 
At July 30, 2008 2:55 PM, Blogger Lloyd said...

B.B.,
Based on comments in today's blog, it seems that very slight bends in the barrel that are NOT too near the muzzle, probably won't adversly affect the rifles accuracy.
I'd appreciate your thoughts.
Thanks,
Lloyd

 
At July 30, 2008 3:00 PM, Blogger B.B. Pelletier said...

Lloyd,

The bend I describe here is at the end of the base block near the breech.It doesn't affect accuracy but it does shift the point of impact up.

B.B.

 
At July 30, 2008 3:11 PM, Anonymous Anonymous said...

B.B.

Back from Ace Hardware. I showed them my front sight and told them about the impact driver. The guy just took a screwdriver, bent in to a crouch, and with a burst of Neanderthal power, got it loose. He was sort of built like one. I asked him what tool he was using, and he said an ordinary screwdriver, but I don't know. It was thick with an enormous handle. It reminded me of my new gunsmithing book where it said that you must not use ordinary screwdrivers which taper. These will fit a bigger variety of screws, but since they concentrate so much force through their taper, they are more likely to tear up screws. That would explain the appearance of some of mine. Instead, the book says to get specialized screwdrivers which do not taper but fill in the screws completely. Do you put any stock in this?

Vince, I think barrel bending to correct droop, even if you got the bend exactly right, would create problems with the sight picture for open sights. And that particular barrel shape might get a few sniggers on the shooting range.

Matt61

 
At July 30, 2008 3:35 PM, Anonymous twotalon said...

Matt61
I'm sure B.B. will tell you the same thing.........
I bought a gun screwdriver set almost 40 years ago and have never regretted it.
You pick out the bit that fits the screw, and use it. No screw damage.
The bits are made to be softer than the screw heads, so the bit will twist before it tears out the screw heads.

twotalon

 
At July 30, 2008 3:56 PM, Blogger Il Bruce said...

I see where there would be a benefit (cost) to the thinner tube barrel. I was curious if any other material is seriously being considered for the business part of the barrel.

I am surprised at the lack of chatter regarding Ben Taylor's smooth twist barrels. I can't get my head around that at all.

 
At July 30, 2008 5:36 PM, Anonymous Anonymous said...

B.B.
First I would like to thank B.B. for all the work he does to provide all of us with SO MUCH information on airgunning and sometimes other topics of related interest. And it is all FREE!!!!
I recently purchased a Walther Falcon - Hunter Edition in .22 which i like very much, except for the trigger mechanism. As shipped my particular rifle had a VERY heavy pull and after about 40 shots started randomly malfunctioning - not wanting to fire without pulling the trigger so hard I could feel the plastic flexxing. So with the help of my older brother(he's an excellent gunsmith) we went into the trigger assembly and after some parts polishing, repositioning and cuting a tiny bit off the sear engagement spring got the trigger to where I think it would normally be "as shipped". It works reliably now but is still much to heavy for my taste. I would like to remove the sear spring and keep it as a backup (since I know it works as is) and put in another sping with lighter compression. My queery is I don't have a source for such small springs. Can you suggest a source, individual or business, that carries an assortment of these types of springs. Thanks, DOC in NC

 
At July 30, 2008 5:49 PM, Blogger B.B. Pelletier said...

Doc,

I would check with Brownells. They have packages of things like springs that might be just what you're looking for. And I presume that a ballpoint pen spring won't work?

B.B.

 
At July 30, 2008 6:26 PM, Anonymous twotalon said...

B.B. and Doc
I have found some good springs at hardware stores, and also have made some out of small MIG wire and single strand steel fishing line leader.
Use caution making your own out of wire....it will poke a hole in your finger very easy.
twotalon

 
At July 30, 2008 6:28 PM, Anonymous Anonymous said...

Twotalon, thanks. Yes, the soft bits were another thing mentioned in my gunsmithing book.

B.B. now that I think about it, I see that when straightening a barrel by hand, any position but absolute vertical would put a huge torque on the part of the barrel resting on the table which one would feel right away and which would make it almost impossible to bend the barrel at all. So an alignment system is already built in.

Matt61

 
At July 30, 2008 6:30 PM, Anonymous Anonymous said...

B.B.

Thanks for the Brownells lead. I didn't think of using a ballpoint pen spring but after looking at it I think the diameter is a bit too big, but I will recheck to be sure.

BTW, looking forward to your post on the Air Venturi Ram Air gas spring upgrade for the Falcon - Hunter Edition. I know you don't like to spill the beans on your upcoming posts but does it at least look promising so far.

DOC in NC

 
At July 30, 2008 8:22 PM, Anonymous Brian said...

Hi Guys,
First time poster, long time reader. So, can someone expand on this barrel bending technique? If I understad the original post correctly it seems like the barrel is bent when the barrel is in the cocked postion. If this is correct how does the table come into play?It seems this would put a lot of pressure ont he cocking are/foot, possibly enough for it to bend.
I am a visual learner, so I often have difficulty conceptulizing things from a written description.
The reason I am asking is I have a sweet Stingray carbine that has not be shot in 2 years becasue the barrel is bent upwards from a similar barrel slam accident. I broke my stock and fortunately bought the last replacement Pyramyd had a while back.
Also, it seems the carbine would be a bit more difficult since the barrel is so short.
I have tried once (unsucessfully) to bend it back by taking off the barrel and tugging on it in a vice.

Thanks,

Brian

 
At July 31, 2008 7:39 AM, Anonymous rickklages said...

Nice to see my name in print! Yes it's true I don't use a sling for shooting I
The table comes into play by supporting the receiver / compression tube while you "over cock" the action. Once the spring is compressed and the sear is set and all the possible slack is removed from the cocking mechanism then the barrel can be straightened. The procedure looks like trying to fold the rifle in half. It does work. The Barrel on the Goldfinger R9 isn't all that long.

Rick

 
At July 31, 2008 8:40 AM, Blogger B.B. Pelletier said...

Doc,

No beans to spill. I haven't seen the gun yet.

B.B.

 
At July 31, 2008 9:20 AM, Blogger B.B. Pelletier said...

Brian,

The table is what keeps the spring tube steady as you press down on the broken (open) barrel. If you are real strong (Incredible Hulk strong) you could just hold the spring tube in your other hand.

Yes there is a lot of pressure on the cocking link. But if you don't horse it, it can take it.

B.B.

 
At July 31, 2008 9:30 AM, Anonymous brian said...

Rick,BB,
Thank you both for the clarification. Seems my "vision" of your technique was correct. FYI, the Stingray carbine barrel is just under 12 inches. I figured less length would = less leverage, thus making it a bit more difficult to bend. I'll give it a try over the weekend and report back. Thank you for the great write up. I'm looking forward to getting the Stingray back in action. It was my "go to" springer prior to the accident. Regarding the cocking arm/link and the Hulk. Good to know it can take it and my incredible arm strength. OK, that last part might be a slight exaggeration, so I plan to use a table.
Brian

 
At July 31, 2008 8:15 PM, Anonymous Anonymous said...

"As you bend it back, you can feel the steel "giving." It sort of shudders as it returns to straight. Once straight, though, it does not want to bend farther, so the resistance increases."

well said.

 
At August 09, 2008 6:54 PM, Anonymous Anonymous said...

Are we on candid camera or something?
You can't bend a rifle barrel back to a 1/8th" group at 20 yards.
Come on folks. Machinists do this thing for a living @ .0001 of an inch and you think You can bend a barrel back by hand and eyeball to plump after being bent. I'll go along but give me a break. lol

 
At August 10, 2008 11:32 AM, Blogger B.B. Pelletier said...

Candid camera,

Learn something today. Gun barrels have always been bent by eye - never by a measuring device, because it isn't accurate enough.

Just as precision lenses are inspected by optical means rather than measuring devices, rifles barrels can be made straighter by eye.

Google the straightening of gun barrels.

B.B.

 
At August 29, 2008 6:16 AM, Anonymous Anonymous said...

reading this thread gave me the inspiration to bend my R1 barrel back in place ... prior to the bend , the rifle was shooting 8 inches high at 10 meters , after the bend , it is shooting 1/2 inch groups at 10 meters ,no adjustments for windage were needed , when scoped , I'm sure it will do better

 
At August 29, 2008 6:24 AM, Blogger B.B. Pelletier said...

Please tell us how the job went after you have straightened the barrel.

B.B.

 

Post a Comment

<< Home