T//C FRAME STRETCH

I was out shooting my 375jdj today and was having alot of misfires, I had this issue when I first got the gun and thanks to you guys I cured it by adjusting my headspace and installing a bellm extra power hammer spring. since then I have probaby put 200+ rounds through it without a problem. not being sure what the problem was I came home and tore down the action and cleaned it but did not see any problems, I then rechecked the headspace with my handy, dandy bellm tool and my headspace was about .001-.002 on all my brass but just for the heck of it I brought it out to +.001, after this I went out and tried it again, same thing, about half the loads I had to hit with the hammer 2or 3 times. this time when I got home I looked the gun over very carefully and noticed that I had an air gap of roughly .005 between the recoil plate and the barrel. I checked my new frame I just purchased with my 7-30 and 30-30 barrel and noted there was no air gap, when I put these barrels on my problem frame there was an air gap, when I put my 375 barrel on the new frame there was a smaller but definate gap. It appears that somehow I have stretched the frame and possibly done something to the barrel. So my point to all of this is have any of you seen this and is it why I'm misfiring and if so will T/C fix it?

Some very helpful hints from Mike Bellm's website:

First, we should perhaps review all the necessary elements to making a Contender fire: In order to fire there is a chain of events that have to happen:

1) The locking bolts must engage the frame far enough to be safe to fire.

2) The locking bolts must rotate the interlock far enough that it FULLY releases the hammer block so that

3) the hammer block is FREE to fall out of the way of the hammer when

4) the striker hits the forward end of the sear, the sear rotates, and at the same time

5) releases the hammer AND the upper arm of the sear releases the hammer block.

Most often the locking bolts not locking all the way is the problem. Two very simple things prevent the locking bolts from engaging into the frame far enough to release the hammer block safety.

1) The top surface of the locking bolts is too high. This is just the particular tolerance variations in a particular barrel and frame combination. Older vintages of barrels and frames may be more prone to this problem, but it happens every day in new, current production as well. It happens.

2) The cartridge case sticks out of the chamber too far due 9 times out of ten to the person resizing cases not understanding how to adjust the size die to bump shoulders back on bottleneck cases. In firing, the frame stretches a bit. This stretch lets the case grow in length from shoulder to head. If this excess length is not removed, it interferes with the barrel closing...... it is too long, too big. Make it right and it will work.

wapitirod,

In my experience, if you have a stretched frame T/C will replace it. The frame stretch problem occurred years ago on the old style frame when the pin that the trigger assy rotates on was at the front of the frame & trigger assy. That doesn't mean that a current generation frame can't stretch. When I had a stretched frame the visible evidence of the stretch was located at the point where the breech block meets the frame rail. There was a visible distortion in the metal at that point. Good luck.

A17Shooter

On my blued encore frame the barrel to frame gap is about .007" on the 243. You can see a gap between the barrel and the frame. So I set my head space at .005" and it goes bang every time. Each barrel will have a different gap on the same frame. I would back out the sizing die and slowly turn it in trying the case in the gun each turn untill it closes without resistance and then check the head space with the Bellm guage. You just might find that the 375 barrel need more head space than .001".

like mentioned..."barrel to frame gap" can vary among frames and barrels. one may have .010" gap....n another combo have only .002" gap. it doesn't mean the frame is stretched......but that you need to adjust your size die to make the brass case "nearly" fill that gap.

you can use
a feeler gauge to get the barrel to frame gap. then use the bellm headspace indicator to read how much case protrudes from the "removed barrel".

a case that goes too deep into the chamber can misfire. likewise, a case that sticks out of the chamber too far, can cause a misfire.
adjust the sizer to account for the barrel to frame gap also.

Kyode, I'll try adjusting headspace and see what happens but whats bugging me is something has changed somewhere with the gun because ever since you suggested that I get the bellm tool several months ago everthing has been great with not so much as one misfire and now out of the blue I get almost nothing but misfires

I had a new problem with my T/C at the range Sunday. After 15 rounds or so it started to misfire. I checked all the usual suspects. These were fireforming cases so I figured that was the problem, wrong. The locking lugs on the bbl had gotten some debris behind them and wouldn't engage the release inside the frame. It would cock and the hammer would drop...no bang. I had to tap the lugs with a brass hammer to free the grit that had settled there. My last hunt was in the deserts of eastern OR. I never fired the gun but everything had a layer of dust on it. That was the problem.

Bill in OR

well guys thanks for all the ideas, I checked everything and I can't find a problem. I switched my 375 barrel to my newest frame and put my 7-30 barrel on what I thought was the problem frame, now everything works I don't know why it works unless it is a subtle machining difference in the frames but as long as they keep working I don't care.

I finally got motivated enough to mess with my 375 again, I got to thinking about what had changed since the gun had started acting up, and I remembered that I had changed the locking spring on the barrel, I installed one of bellms heavy duty springs. I removed the spring and went back out and had no misfires. I don't exactly know what the spring had changed to cause it to start misfiring but it was definately the culprit.

wapitirod

It's hard to tell if your frame has stretched if you didn't have a "starting benchmark", to measure frame stretch. Unless you think your frame has been enduring high pressure loads, frame stretch is unlikley. I'm not ignoring your headspace measurements that you have discovered, your mechanical mods, or satisfactory functioning with other barrels.

I am a studied and practiced wildcatter. Might be able to help. Sometimes things aren't as bad as they seem.

That being said, regardless of frame stretch, you can still reliably make your gun go bang, or in the case of the 375 JDJ...BOOM.

KISS- Keep It Simple.

Some prerequisite questions, to see if it is Simple.

#1 Did you start with virgin 444 brass, or once fired brass, and neck it down, or are you loading formed/factory brass from your all ready proven gun?

#2 I need to know the answer to question #1 to help you farther. If you started with once fired or virgin brass, discribe how you set your sizing die, in relation to the shell holder.

I'm using virgin brass and I adjusted the sizing die using one of bellms headspace gauges, I've got it so I'm about .001 above flush but like I said in my last post for some reason when I went back to the factory barrel lock spring it started working again but any input you have would be greatly appreciated

Sounds like you solved your problem.

Anyway, here's my procedure for fitting cases to my chamber.

Screw the sizing die down till it touches the shell holder with the ram raised. Unscrew the sizing die 2 1/2 turns and run a case through the die. Remove case form shell holder and place in chamber of gun, try to close action without forcing the gun closed. You shouldn't be able to close the action. Return the case to the press and begin turning the sizing die about 1/4 - 1/8 turn (less as you get closer to closing) at a time, till you can just close the action of the gun on the case.

This will achieve perfect head space even if your headspace has increased do to minor frame stretch, thrust plate setback, or a chamber cut a little too deep.

If this doesn't solve ignition problems, it's probably mechanical or rarely, primer pockets cut to deep.