What effect would having a barrel bolt too tight or too slack on a break barrel?

Medievalturner

Medievalturner

Super member
Joined
Jul 11, 2022
Messages
1,576
Reaction score
2,565
Location
West Cumbria
Just a query, (apart from the obvious, where if it was too tight you can't break the barrel), what other effects could be expected from a barrel bolt which is either too tight or too slack?
Is it possible that ( let's for arguments sake say the barrel bolt didn't screw into the compression tube without some manipulation) ie the compression tube (most likely) is slightly out meaning the bolt doesn't engage with the female threaded side of the tube without help.
With it fitted, eventually, has this slight misalignment, with the bolt too tight or slack, totally ruined any chance of the breach seal working to it's designed function, even though this mis alignment cannot be measured easily once it is back together.
 
Too tight usually shows up in vertical stringing of the groups. To loose and it's likely to be more random or horizontal on the groups. You also have to look after the detent plunger and keep the stop lug clear of debris. There's also the changing of the breech seal which sometimes changes point of impact. A break barrel gun will require some adjusting, but maybe only every 10,000 shots, or so. Depends on the quality of the gun. Sounds like a lot of trouble, but they usually don't give much trouble.😁
 
I think it's neither too much nor too little; there's a middle ground. Once tightened, try moving the barrel by hand and check for any internal movement. If it's rigid without any play, that's a good sign. Another parameter for me, for example with Weihrauch HW 35s, is the sound the rifle makes when opening and closing it. It should be a clean sound, and if you like, a high-pitched one—a sound that will give you the certainty of a perfect opening and closing.
 
I've some limited experience which did surprise me. I was pellet testing after a rebuild and noticed the barrel was very easy to close after cocking, some free play could be felt by moving the barrel side to side. Groups were decent tho. Anyway in the quest for even better groups I tightened the barrel so slight resistance was felt upon closing, the barrel would just about hold its own weight after cocking. Back to the range with great anticipation, the groups were worse!
I can't pinpoint why. They just were.
Maybe barrel lock up was more consistent with a slacker barrel. Maybe some recoil or vibration is not taken up by the loose fit barrel.
Wasn't what I expected.
 
andy96j said:
I've some limited experience which did surprise me. I was pellet testing after a rebuild and noticed the barrel was very easy to close after cocking, some free play could be felt by moving the barrel side to side. Groups were decent tho. Anyway in the quest for even better groups I tightened the barrel so slight resistance was felt upon closing, the barrel would just about hold its own weight after cocking. Back to the range with great anticipation, the groups were worse!
I can't pinpoint why. They just were.
Maybe barrel lock up was more consistent with a slacker barrel. Maybe some recoil or vibration is not taken up by the loose fit barrel.
Wasn't what I expected.
Click to expand...
Each rifle is a laboratory, full of curiosities and effects. And we're impressed by what we don't expect. We want them to work logically, but steel is sometimes capricious. And perhaps it needs time and testing. Perhaps instead of tightening too much, it's better to gradually develop a minimum tightness and test. Perhaps the best results come from small modifications.
 
A too loose bolt causes a shotgun-like spread. Like on my brand new but shitty Cometa Fusion air rifle. The barrel comes loose on its own after a few shots. Completely useless. Beware of Cometa air rifles. :(
 
springer.22 said:
The barrel comes loose on its own after a few shots. Completely useless. Beware of Cometa air rifles. :(
Click to expand...

I have 2 with zero issues.
Did you purchase new, and is the grub screw that locks the barrel cross bolt still in situ?
I think that all the Cometa niggles have already been addressed on these pages, but loose barrels and dodgy detents is a new one, the lock ups on mine are both bank vault Shrug tt
 
2506sendero said:
I have 2 with zero issues.
Did you purchase new, and is the grub screw that locks the barrel cross bolt still in situ?
I think that all the Cometa niggles have already been addressed on these pages, but loose barrels and dodgy detents is a new one, the lock ups on mine are both bank vault Shrug tt
Click to expand...

I have a Cometa 220 in .177. Love this Light and accurate little rifle.
Shoots JSB 8.44 pellets at 623 fps with the old silver, softer OEM spring. The firing cycle is lovely. No problems with it. It is made with the old grub screw safety.

I bought a Cometa Fusion two weeks ago. It is made with the newer barrel locking mechanism. No grub screw, just a single T25 Torx head barrel cross bolt secured with two washers. Only 6-10 shots and this barrel screw comes loose. The barrel starts to wobble, the power drops to 12 fpe, and the spread becomes terrible.

I wrote to Cometa about this problem, they ansvered that the tightening torque of the barrel screw is 8 Nm.

I just tried to put it together with blue Loctite threadlock and I don't know if it will work. It's not normal to have to glue a new gun. :(

I was very disappointed with the quality of the Cometa.
 
springer.22 said:
I have a Cometa 220 in .177. Love this Light and accurate little rifle.
Shoots JSB 8.44 pellets at 623 fps with the old silver, softer OEM spring. The firing cycle is lovely. No problems with it. It is made with the old grub screw safety.

I bought a Cometa Fusion two weeks ago. It is made with the newer barrel locking mechanism. No grub screw, just a single T25 Torx head barrel cross bolt secured with two washers. Only 6-10 shots and this barrel screw comes loose. The barrel starts to wobble, the power drops to 12 fpe, and the spread becomes terrible.

I wrote to Cometa about this problem, they ansvered that the tightening torque of the barrel screw is 8 Nm.

I just tried to put it together with blue Loctite threadlock and I don't know if it will work. It's not normal to have to glue a new gun. :(

I was very disappointed with the quality of the Cometa.
Click to expand...

That's not good, and i didn't realise that they had changed the design around the barrel lock up Homer face palm
 
I have two BSA Meteors, a wall hanger MK5 and a scruffy MK3 Super Meteor. Thanks to BSA's design genius, the forward stock mounting can pull the breach apart. Requiring it to be gently reset. On my MK5, due to the condition, I've not done this. Result: about 5mm lateral movement at the tip of the barrel.
The scruffy Super Meteor, I've tightened it up carefully, with the result being that it is an accurate little bugger at closer ranges.
 
You must log in or register to reply here.
Back
Top