I have an older style contender frame with serial number around 235K. When using my 44mag or 6mm-223 barrel, the action opens as soon as the round is fired.

I know it's not the lugs on the barrels because I have 3 other actions that these two barrels work properly in. The 44 is coming open with minimum powder loads using 240gr bullets.

Is ther something that needs to be done to the action? Or something that can be repaired?

I never had this happen to any of my other actions, even using the 375JDJ or 300 savage.

Any suggestions would be appreciated.

HL

Its the bolts (they are technically not lugs) but since you know its not them..........I have no clue. When you figure out what it is.....I'll sell you a set of bolts.

Ask Mike Bellm. He'll have an idea what it could be. I think his website is www.bellmtcs.com If not do a search, you'll find it. Let us know what it turns out to be.

I'll give mike a call. This really has me confused and concerned. I can use either barrel in a separate, newer action and there's no problem. The hinge pin is still tight, so I know there has been no stretching of the frame. Plus, I don't shoot at or above max loads.

You would think if the 6mm and 44mag would pop open an action, the 300 savage and 375JDJ would also.

First time this has happened in over 20 years of contender shooting and I'm perplexed.

Time to give Mike a call.

Thanks gentlemen,

HL

You make the assumption that all your frames are the same...........

I know they are all different to a certain extent. This problem is coming up with the same action I purchased first and used with this barrel for over 15 years.

Action closes with a good snap sound and everything appears to be solid with no slop.

That's kind of my dilema.

I already sent a message to Mike and I will see if he has any insite. I'm stumped.

The only thing I have not done is replace the springs. I guess that could be it.

Aside from the possibility of needing a new set of longer bolts, don't overlook trace amount of oil or lube in the chamber or on the brass. Even with mild loads, if the brass can't grip the chamber walls, excessive backthrust can be the result -- and that can actually unlock a frame.

Also, make certain that the bolts can move freely. On a custom barrel I ordered a few years ago, the first shot forced the frame open. Some type of grit or polishing compound was the culprit, and after cleaning that out, it performed flawlessly.

"When using my 44mag or 6mm-223 barrel, the action opens as soon as the round is fired.

I know it's not the lugs on the barrels because I have 3 other actions that these two barrels work properly in. The 44 is coming open with minimum powder loads using 240gr bullets."

I think you are making a mistake here. Just because it's ok on the other frames don't mean it good that one. I'd still ink the lugs & check to see if your getting complete lock up. If not you need to fit the lugs to that frame if it's where they are going to be used. Also I believe that Mike Bellm sells heavy duty lock lug springs as well. That might be a solution if nothing else works. If it's an old frame the springs could have lost some of it's strength. Just some things to think about. gGood luck!

Now ..........would you like a heavy spring and a split bolt set or do you still "know its not that" ?

Rich and SKB, you guys are probably on to something. since those are my two oldest barrels and I have shot those two probably 10X more than any of my other barrels.

I'll get in touch with mike and try the heavy springs. The barrels are already equipped with split bolts. Both of these barrels were custom barrels from Mike back in 1985 and 1986.

I had the same problem with an older frame. I sent it off to TC and they replaced the entire gun.

I should be getting the heavy duty springs from MB within a week or so, and I will give that a try and see if it solves the problem. For now, I have my 22 hornet on that action. I seriously doubt that it will cause the action to fly open, but will find out this weekend.

If the spring doesn't correct the problem. I will be sending the action off to TC and see what can be done.

I had this happen on two of my frames, on a 7TUC & 7BR, and I sent them back to Thompson for repairs. When I got them back that problem was corrected. They were fast , it took about 2 wks. turn around time. Oh they requested the barrels sent along with the frames. I don't belive there was a charge from Thompson, but shipping was expensive. That was a few years ago, why don't you give Thompson a call. Lee

Leland-Who chambered your 7mm BR barrel? Just curious...

HL, there is an article on the main www.bellmtcs.com site about barrels flying open.

What usually happens is a marginal lock up, one that just does allow the interlock to clear the hammer block when the barrel is closed, leaves a smaller contact area between the locking bolts and the frame's locking table.

Over time and use, the locking table surface becomes worn and rounded partly due to more force being applied on a smaller area.

Take the trigger group out of the offending frame and examine the locking table surface. Do the same for other frames and compare them. I think you will see the difference.

Dropping the top surface of the locking bolts some to increase the engagement under the locking table may put it back to normal.

I use the No. 11F Diamond EZE Lap for honing down the top surface of the locking bolts.... just the plane the "U" notch is in..... NOT an part inside the locking bolt slot in the barrel lug, just what is exposed.

I say this because if you remove any material from the locking bolts where they contact inside the barrel lug, it increases the amount the bolts can tilt in the slot and aggravates the problem.

Do use the Heavy Duty Locking Bolt Springs also. I will be a little surprised if the springs alone will stop the barrels from flying open, but they might.

Keep me posted.

Mike Bellm

I'm just about to the point that I can dedicate one action to a barrel. For now, I have my hornet barrel on that action and so far no problems. I still plan on putting your springs on the other two barrels, mainly because they feel light when pushing down on the bolts in comparison to the other barrels.

If the action stays closed on the hornet barrel and I leave it that way, I can live with that rig.

Thanks for the help, you should have my order by now. Look forward to talking with you soon.

HL