BT-99 underlug comes unlocked upon firing

williamd · September 23, 2007, 09:37 PM

I shoot with a buddy who has BT-99 2 bbl set. It has had a lot of rounds through it but less than half as many as mine, and I only have one bbl. Mine has had zero defects in the 15 years since I bought it used. His is not locking properly and the 32" bbl unlocks when he fires. Seems very tight when I try to work it by had. I cleaned and looked for suspected debris but found nothing. Compared with his 34" bbl and no visible difference. Locking bolt/lugs look okay. Open to any suggestions we can try????? I suspect this can occur in any under lug break action so maybe some experience out there?

williamd · September 24, 2007, 11:41 PM

Come on .... one of you guys knows something about this!!!!

Jim Watson · September 25, 2007, 07:13 AM

Yes, but they work for Browning.
I think that a warranty matter, especially if the gun came as a two-barrel set.

steve1589 · September 25, 2007, 07:49 AM

Well, if it unlocks when fired that barrel is not fitted properly. Since, he has got a two barrel set put on the barrel that does not come unlocked when fired. With the firearm unloaded, close the action. Now look at the position of the top lever. Take some masking tape and slide it under the top lever. You may have to degrease this area before it will stick. Now take a pencil and trace around the bottom half of the top lever. Now take that barrel off and put the one that does not lock up on. Look at the top lever. Is it in the same location as the pencil line or is it more to the right of it. If it is to the right of the pencil line the locking block is not getting enough of a bite on the underlug. Which is why it comes open under recoil. If this is the case the underlug of the barrel that does not stay locked needs to be refitted.

williamd · September 25, 2007, 10:44 AM

Thanx all. This is an older set that only started the unlocking ... after several thousand rounds. Lever is exactly centered .. which is unusual in my experience.

I am gonna get a repair kit and rebuild the entire lever/locking mechanism. Will let you know.

Heh, heh ... work for Browning. Maybe so. That's okay, Brn has been very good. Can't say the same for the after-Bill Ruger company.

Harry Bonar · September 27, 2007, 07:23 PM

Sir:
Several things can cause this.
First and foremost the locking bolt is incorrectly fit - that's just the beginning of trials.

The entire breech is misfit in that whem the shell goes off the force of the case head comes against the front of breech face and "stresses" the action frame.
If the "standing breech" is not accurately fit the bbls go up or down and tempaorarily loostens the locking bolt. or, there may be play back in the action where the rear of the locking bolt pivots!
The locking bolt is only fit on one side, or, just fit in the center etc.

This is the reason African double rifles are so expensive - the breech fit, reliability and bbl. point of impact. Many African hunters are now using bolt-action rifles in preference to doubles. es, I think the double is slightly faster than the bolt, but not much and the bolt can stand far higher pressure cartridges.
There can also be longitudinal play in bbl./action fit - tested by removing forend and len testing for play - this would be very unusual in any quality rifle.
Send it back to the manufacturer.
Harry B.

CCW1911 · October 7, 2007, 11:53 PM

A new spring for the opening lever will usually do the trick, brownells has them I think. Easy to replace just pull the buttstock, one screw holds it on.

williamd · October 13, 2007, 08:52 PM

Lots of good help from a couple of gun blogs ... if this forum is a blog.

Got most parts from Browning. Tried for a new lug/bolt form Midwest Guns but Browning has made that a factory item ..... and will fit it for you in a mere 4 - 6 months! Too bad Browning, like Ruger, has decided that we are all incompetent. Even smiths.

But, while waiting for all but the bolt I completely disassembled the gun to the last screw and firing pin. [That dang firing pin spring requires 3 hands!]This is a 1978 gun and I doubt it has ever been taken completely down. A half can of GunScrubber and literally digging 'gunk' (technical for a coagulated mix of oil and dirt) out of every corner, lubing LIGHTLY and reassembling it is working. Also GENTLY took the smooth shine off the bbl lug.

Have the new parts in reserve.

Browning was really good to deal with (order of magnitude better then Ruger!) but I hate I can't get parts for my own firearms.

Oh, another while waiting ... I picked up a new Remington 1100 Competition. If you like 1100s you'll love the Comp. Only one I have seen in a shop so grabbed it. Great wood. I did work over the trigger after one round of trap and went from 17 to 25 (which I expect at 16 yds). Comes with skeet, IC, light M, M and F choke tubes. I want one XF so am looking ... it is a different tube than standard 1100 else I'd be in fat shape. Gas piston different, too. Trigger group the same (I switched to be sure). So, a few 'new' parts to add to the travel kit. I carry piston set, o-rings, firing pin, complete trigger group, magazine cap [

], follower, extractor and spring, ejector spring, staking tool and a few odd things in a sealed baggie. Have given away more then I have used but .....

September 23, 2007, 09:37 PM	#1
williamd Senior Member Join Date: March 13, 2007 Location: SoCal Posts: 801	BT-99 underlug comes unlocked upon firing I shoot with a buddy who has BT-99 2 bbl set. It has had a lot of rounds through it but less than half as many as mine, and I only have one bbl. Mine has had zero defects in the 15 years since I bought it used. His is not locking properly and the 32" bbl unlocks when he fires. Seems very tight when I try to work it by had. I cleaned and looked for suspected debris but found nothing. Compared with his 34" bbl and no visible difference. Locking bolt/lugs look okay. Open to any suggestions we can try????? I suspect this can occur in any under lug break action so maybe some experience out there? __________________ "Outlaw guns and only outlaws will have guns!" Unfortunately, we may be moving in that direction. NRA Benefactor, Conservative!, VN '64-'65. Never sell a gun or a car ... and retire rich!

September 24, 2007, 11:41 PM	#2
williamd Senior Member Join Date: March 13, 2007 Location: SoCal Posts: 801	BT-99 Help Come on .... one of you guys knows something about this!!!! __________________ "Outlaw guns and only outlaws will have guns!" Unfortunately, we may be moving in that direction. NRA Benefactor, Conservative!, VN '64-'65. Never sell a gun or a car ... and retire rich!

September 25, 2007, 10:44 AM	#5
williamd Senior Member Join Date: March 13, 2007 Location: SoCal Posts: 801	Thanx all. This is an older set that only started the unlocking ... after several thousand rounds. Lever is exactly centered .. which is unusual in my experience. I am gonna get a repair kit and rebuild the entire lever/locking mechanism. Will let you know. Heh, heh ... work for Browning. Maybe so. That's okay, Brn has been very good. Can't say the same for the after-Bill Ruger company. __________________ "Outlaw guns and only outlaws will have guns!" Unfortunately, we may be moving in that direction. NRA Benefactor, Conservative!, VN '64-'65. Never sell a gun or a car ... and retire rich!

September 27, 2007, 07:23 PM	#6
Harry Bonar Senior Member Join Date: December 5, 2004 Location: In the Vincent, Ohio general area. Posts: 1,804	unlocking Sir: Several things can cause this. First and foremost the locking bolt is incorrectly fit - that's just the beginning of trials. The entire breech is misfit in that whem the shell goes off the force of the case head comes against the front of breech face and "stresses" the action frame. If the "standing breech" is not accurately fit the bbls go up or down and tempaorarily loostens the locking bolt. or, there may be play back in the action where the rear of the locking bolt pivots! The locking bolt is only fit on one side, or, just fit in the center etc. This is the reason African double rifles are so expensive - the breech fit, reliability and bbl. point of impact. Many African hunters are now using bolt-action rifles in preference to doubles. es, I think the double is slightly faster than the bolt, but not much and the bolt can stand far higher pressure cartridges. There can also be longitudinal play in bbl./action fit - tested by removing forend and len testing for play - this would be very unusual in any quality rifle. Send it back to the manufacturer. Harry B.

October 13, 2007, 08:52 PM	#8
williamd Senior Member Join Date: March 13, 2007 Location: SoCal Posts: 801	Lots of good help from a couple of gun blogs ... if this forum is a blog. Got most parts from Browning. Tried for a new lug/bolt form Midwest Guns but Browning has made that a factory item ..... and will fit it for you in a mere 4 - 6 months! Too bad Browning, like Ruger, has decided that we are all incompetent. Even smiths. But, while waiting for all but the bolt I completely disassembled the gun to the last screw and firing pin. [That dang firing pin spring requires 3 hands!]This is a 1978 gun and I doubt it has ever been taken completely down. A half can of GunScrubber and literally digging 'gunk' (technical for a coagulated mix of oil and dirt) out of every corner, lubing LIGHTLY and reassembling it is working. Also GENTLY took the smooth shine off the bbl lug. Have the new parts in reserve. Browning was really good to deal with (order of magnitude better then Ruger!) but I hate I can't get parts for my own firearms. Oh, another while waiting ... I picked up a new Remington 1100 Competition. If you like 1100s you'll love the Comp. Only one I have seen in a shop so grabbed it. Great wood. I did work over the trigger after one round of trap and went from 17 to 25 (which I expect at 16 yds). Comes with skeet, IC, light M, M and F choke tubes. I want one XF so am looking ... it is a different tube than standard 1100 else I'd be in fat shape. Gas piston different, too. Trigger group the same (I switched to be sure). So, a few 'new' parts to add to the travel kit. I carry piston set, o-rings, firing pin, complete trigger group, magazine cap [], follower, extractor and spring, ejector spring, staking tool and a few odd things in a sealed baggie. Have given away more then I have used but ..... __________________ "Outlaw guns and only outlaws will have guns!" Unfortunately, we may be moving in that direction. NRA Benefactor, Conservative!, VN '64-'65. Never sell a gun or a car ... and retire rich!

September 25, 2007, 07:13 AM	#3
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,541	Yes, but they work for Browning. I think that a warranty matter, especially if the gun came as a two-barrel set.

September 25, 2007, 07:49 AM	#4
steve1589 Member Join Date: December 12, 2005 Posts: 55	Well, if it unlocks when fired that barrel is not fitted properly. Since, he has got a two barrel set put on the barrel that does not come unlocked when fired. With the firearm unloaded, close the action. Now look at the position of the top lever. Take some masking tape and slide it under the top lever. You may have to degrease this area before it will stick. Now take a pencil and trace around the bottom half of the top lever. Now take that barrel off and put the one that does not lock up on. Look at the top lever. Is it in the same location as the pencil line or is it more to the right of it. If it is to the right of the pencil line the locking block is not getting enough of a bite on the underlug. Which is why it comes open under recoil. If this is the case the underlug of the barrel that does not stay locked needs to be refitted.

October 7, 2007, 11:53 PM	#7
CCW1911 Junior Member Join Date: April 1, 2005 Location: harrison, ar Posts: 11	A new spring for the opening lever will usually do the trick, brownells has them I think. Easy to replace just pull the buttstock, one screw holds it on.