Barrel Bending Diana 34

Bedrock Bob

Member
Jul 18, 2024
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A couple years back I decided to have my D34 tuned and a Vortek kit installed. I shipped it to a reputable Smith and things were just groovy. Upon return the box was damaged but the gun looked fine. I mounted a scope and zeroed it. No problems. It shot beautifully.

A few weeks ago I decided to take the scope off and shoot it bare. When I zeroed the iron sights I noticed the back sight was screwed left almost to the limit. A quick check revealed the scope too was zeroed almost to the limits of the windage screw. A careful check with a straight edge showed a very slight, almost imperceptible bend to the right. It must have been damaged by UPS when they shipped it back. I just didn't realize it.

I did some research and decided to bend the barrel back to center. I made sure the front sight was plumb and centered the rear sight. I made up a maple jig that fit the barrel then set the whole mess in my bench vice and proceeded to add pressure.

A straight edge across the top from the front post through the rear sight told me exactly how much bend I was giving it. I would apply force until I got a bend and then test fired a pattern.

I started slow and the first few tries the barrel would just spring back to the same POI. But after a brief learning curve I started to make headway. The gun started out shooting 4" right at 10 yards. After 13 "bends" I got the pattern right in the middle of the dot.

I optically centered the scope using a mirror and mounted it on the rifle. It was 4 clicks right and 10 clicks low at 25 yards.

The entire process from making a jig to sighting the scope took less than 2 hours. The gun shoots as good or better than it did before. No affect on accuracy at all.

I sweated and fretted the first few bends. That barrel was WAY over to the left when I put pressure on the jig. But it sprang back nicely. When it was all said and done you couldn't tell it was ever bent. Now when passing a straight edge across the (centered) sights it comes across the center of the receiver at the rear. When I started the process it was at the extreme left edge.

I was so happy with the results I decided to bend a hatsan 95 barrel that had snapped up and bent. It was easy. 3 bends and it brought the POI back down to zero at 25 with an optically centered scope. The iron sights jibe perfectly. I didn't touch the scope adjustments at all to get zero. The rear iron sight is pretty much centered in its vertical travel. Horizontally it zeros exactly in the center.

What a hoot. I would have never thought you could bend a barrel back straight again with a stick and a vice. Well I was wrong. You can. It's not difficult at all and it's a bunch better than dealing with adjustable mounts and scope shims.

Attached is a photo of the rifle and the jig I made to straighten the barrel. Just a piece of maple cut to length with a lug at both ends. I cut a saddle in the front lug for the barrel. The rear lug is square and rests against the pivot block. It's as simple as clamping it in a vice and turning the handle until you think it bent a little. Then test firing and repeating until the rifle's POA and POI are in the same spot.

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I do hope you removed the shroud and spring around the barrel before that.
I didn't remove anything. I took the action out of the stock to bend and re-assembled to test fire.

There is no shroud nor spring around the barrel of this rifle. You can see the muzzle in the photo. There is just a front sight up there.

The maple jig fits around the barrel behind the sight. The pressure is on the barrel alone.

The Hatsan has some baffles in a plastic lug. The barrel does not extend very far into that assembly. Again I put the saddle over the barrel. Not the "suppressor" assembly.


It takes a buttload of force to bend a barrel. If you rested that jig on a plastic part and torqued it you are going to break something. Common sense dictates that the jig apply force to only the part that needs bending.
 
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A couple years back I decided to have my D34 tuned and a Vortek kit installed. I shipped it to a reputable Smith and things were just groovy. Upon return the box was damaged but the gun looked fine. I mounted a scope and zeroed it. No problems. It shot beautifully.

A few weeks ago I decided to take the scope off and shoot it bare. When I zeroed the iron sights I noticed the back sight was screwed left almost to the limit. A quick check revealed the scope too was zeroed almost to the limits of the windage screw. A careful check with a straight edge showed a very slight, almost imperceptible bend to the right. It must have been damaged by UPS when they shipped it back. I just didn't realize it.

I did some research and decided to bend the barrel back to center. I made sure the front sight was plumb and centered the rear sight. I made up a maple jig that fit the barrel then set the whole mess in my bench vice and proceeded to add pressure.

A straight edge across the top from the front post through the rear sight told me exactly how much bend I was giving it. I would apply force until I got a bend and then test fired a pattern.

I started slow and the first few tries the barrel would just spring back to the same POI. But after a brief learning curve I started to make headway. The gun started out shooting 4" right at 10 yards. After 13 "bends" I got the pattern right in the middle of the dot.

I optically centered the scope using a mirror and mounted it on the rifle. It was 4 clicks right and 10 clicks low at 25 yards.

The entire process from making a jig to sighting the scope took less than 2 hours. The gun shoots as good or better than it did before. No affect on accuracy at all.

I sweated and fretted the first few bends. That barrel was WAY over to the left when I put pressure on the jig. But it sprang back nicely. When it was all said and done you couldn't tell it was ever bent. Now when passing a straight edge across the (centered) sights it comes across the center of the receiver at the rear. When I started the process it was at the extreme left edge.

I was so happy with the results I decided to bend a hatsan 95 barrel that had snapped up and bent. It was easy. 3 bends and it brought the POI back down to zero at 25 with an optically centered scope. The iron sights jibe perfectly. I didn't touch the scope adjustments at all to get zero. The rear iron sight is pretty much centered in its vertical travel. Horizontally it zeros exactly in the center.

What a hoot. I would have never thought you could bend a barrel back straight again with a stick and a vice. Well I was wrong. You can. It's not difficult at all and it's a bunch better than dealing with adjustable mounts and scope shims.

Attached is a photo of the rifle and the jig I made to straighten the barrel. Just a piece of maple cut to length with a lug at both ends. I cut a saddle in the front lug for the barrel. The rear lug is square and rests against the pivot block. It's as simple as clamping it in a vice and turning the handle until you think it bent a little. Then test firing and repeating until the rifle's POA and POI are in the same spot.
Great job, and a good example of a "quality " post
 
Nice work Bob!

As a teenager having access to a well equipped workshop I did a lot of gunsmithing for my friends. Bent springer barrels happened and I had a similar jig for straightening them. I fixed a dozen or so over the years.

Most of my gunsmithing was in tuning and custom fitting stocks when the guys out grew them. The fee for the work was paid with cans of pellets.

Like you said, it's a bit unnerving when you start but you quickly get the feel for how much force to use and how much spring-back there will be.

Six decades later I'm back to tuning airguns and making stocks 😀

Cheers!
 
Well done and thanks for the count of times bending . Lot of small bends !
I would bend the barrel on my precious Diana rifle until I freaked out about how much it was bending. About the time I was sure I destroyed it I'd release the pressure. That would get me about 1/8" I'm my POI. Really springy. The muzzle had at least an inch left deflection under torque. Many tries produced no change in POI. But I just kept it up being careful not to overdo it and eventually it came around.

I put the Hatsan in the vice and I felt it bend back the first try. I probably was less concerned about it and started with more force. The barrel was bent worse and all in one spot. But it came right out. The barrel was shorter than the Diana so less leverage. Still things required a lot less pressure to get a bend.

I think the moral of the story is to go slow and test often. I'd rather try 10 times and not get a bend than fold it over like a taco with a big heave ho.
 
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I didn't remove anything. I took the action out of the stock to bend and re-assembled to test fire.

There is no shroud nor spring around the barrel of this rifle. You can see the muzzle in the photo. There is just a front sight up there.

The maple jig fits around the barrel behind the sight. The pressure is on the barrel alone.

The Hatsan has some baffles in a plastic lug. The barrel does not extend very far into that assembly. Again I put the saddle over the barrel. Not the "suppressor" assembly.


It takes a buttload of force to bend a barrel. If you rested that jig on a plastic part and torqued it you are going to break something. Common sense dictates that the jig apply force to only the part that needs bending.
Sorry my mistake. I mixed it up with the 48.