Gentlemen -
Posted this in here early this year, or late last year, and somehow (old age, senility) can't seem to find or remember the responses.

Nephew has a 7TCU Contender that SOMETIMES does not fire (maybe 2 out of 10 times, but, it might also go 20 times without a misfire). A second, sometimes third, attempt will always get the gun to fire. It looks like the indent in the primer on the ones that don't fire the first time is a little light.

The problem occurs on the initial fireforming load as well as loads worked up after the cases are fireformed (neck sized only).

The consensus was, if my feeble mind is working properly, that there was a problem with the hammer spring, or something (I know ZERO about Contenders). Does that sound right? If not, any suggestions for a fix?

Thanx,

R-WEST

First check your sizing dies. They maybe adjusted too far down & causing your misfires. Take a look at the linc here for an explanation. Then you can check your hammer spring if you think that is suspect. The linc to the article for Mike Bellm is very good & should be able to help.

http://www.bellmtcs.com/FAQ/contender_misfires.htm

Rich Jake

Rich -

Thanx for the link. Now I have to track down the nephew and get the Contender to check things out. According to Mike's article, the cases may need to be sized down MORE, not less.

R-WEST

I like the misfire.... they make me nervouse and jittery and show me just how much I'm flinching.

Check the bolt (below the extractor) The older ones are one piece, occasionally prevent the
hammer block from deactivating, especially when an older barrel is mated with a newer frame. This same problem cost me trophy buck.... that watched me recock TWICE.
Newer ones are split in two. Contact TC for replacement, they sent mine free of charge.

R-WEST
Sorry I may have said it wrong, but That's why I posted the linc so you would get the right info!
Rich Jake

R-WEST when you have a missfire can you see the firing pin mark on the primer If you can this would show the case is to short and you need to back your die off some or if you can not see the firing pin mark on the priner your case is to long and the gun is not locking up all the way and you will need to move your die down some more. With this one your hammer will not hit the frame the firing pin block will not drop do to the action not being locked up all the way. So when you have a missfire check the hammer

This has happened to me before and all your explanations have been on my mind already , but if I have a mark on my primer (a fairly good one) why does it sometimes take 3 firings to make it go bang ? The case doesn`t get any longer so headspace can`t be the problem , after all , my 30/30 Ackley Imp. has a rim to headspace (at least more than a 7 TCU) and if the die has sized 100 cases why should a single one be different then ? I used to blame the primers , but after I`ve switched them around from brand to brand , I seriously doubt they are the reason ! Just my 2 cents worth.....!I`ll really appreciate ALL of your help on this , SOS !

R-WEST
Mike is a wealth of info. He posts here often. So if you run into problems investigating your barrel just email him through his website or post the question to him. He has answered many questions for the people who post here. I think you'll find the problem shortly.
Good luck
Rich Jake

R-WEST : Obviously you`re not familiar with the german language (I don`t blame ya ) !We have three more letters in the alphabet , � , � , and � ,they basically consist of ae , oe , and ue put together into one single letter !My keyboard has them , as well as the � , which is short for ss !
I guess we should open a class for beginners in german ?! Did you know that german almost became YOUR official language ? As far as I know it was short only one single vote in the congress !

I thought that one vote against was also called WWII!

Instead of Heretic, my title should be "Myth Buster."

The mere presence of a rim does not stop problems of headspace, which can be positive or negative.

Zero headspace means exactly that, no space between the case head and breech face.

In the positive direction, an actual gap, the case cannot interfere with the barrel locking up completely.

In the negative direction, NO gap but actually an interference between the case head and breech face, the case is too long..... AS DETERMINED FROM THE SHOULDER TO THE CASE HEAD. It then sticks out of the chamber too far and prevents the barrel from closing all the way.

The locking bolts engage in the frame enough that the barrel won't fall open, but the bolts do not rotate the little plate inside, called the interlock, far enough that it will clear the bottom of the hammer block safety and let it drop freely.

The hammer then knicks the top of the block on its way down and loses enough energy in the process that it won't be able to fire the primer.

The problem never goes away..... until folks learn to think out of the box the magazines and loading manuals keep them trapped in.

In regard to case rims and bottle neck cartridges, the rim counterbores have to be cut deeper than the thickness of the thickest case rim, whose dimensions can vary greatly. If not, then some ammo will not let the barrel close. TC often takes this to the extreme. I often find rim cuts at full maximum SAAMI depth, coupled with a barrel to frame gap of .004 to .005" or more, which adds up to really excess headspace and case stretching. Thus, you must learn to adjust the size die so that case heads will protrude from the end of the barrel no more than what the actual barrel to frame gap measures, ideally only about .001" less than the actual gap.

I still have not had time to make an indicator base to sell for this purpose, but with a dial indicator set up as I envision it, measuring will be quite simple for anyone to do. As it is, you have to either guesstimate or go to the expense of a depth micrometer, which is also a tad tricky to use while balancing it on a case head trying to feel if it is sitting dead flat on the case and giving a true measurement of the case head protrusion. I use both methods in the shop, and inspite of over 23 years working with a depth mike, the indicator is much easier to use with greater accuracy.

Per articles I have written on the website, using a thickness or two of paper as a comparative guide is good for "layman" use to see a relative difference between the gap and the case head protrusion.

Once again, read "The Experiment Every Contender Shooter Should Perform" on the website. What is written above here is just the short course. Doing the experiment will make it much clearer for you.

Look for info also about checking locking bolts for adequate engagement. Without interference from a case sticking out too far, a barrel may not lock up adequately due to the top of the locking bolts being a bit too high in relationship to the locking table in the frame.

Misfires are no mystery at all. There are definite reasons they occur, and while replacing a hammer spring, which should be done periodically anyway, MAY stop misfires temporarily, you must go back to square one.

Square one: Things work better when the ammo fits the gun. Imagine that. What will they think of next?

Now you know what to look for. Have fun.

Mike

[ 10-15-2002, 20:57: Message edited by: Mike Bellm ]

Gentlemen - Thanks much for the responses. Now, all I have to do is get the Contender and start checking things.

At least, this year we might have some time to actually work on it. He dropped the gun off at Thanksgiving last year, and asked me to work on some loads for deer season (starts the Monday after Thanksgiving) and mentioned "Oh yeah, sometimes it doesn't go off. See if you can figure it out."

Thanks again.

(edit) Mike - Thanks for the info; I posted your data at another site (ReloadBench.com), as well, with due credit to you.

R-WEST

[ 10-16-2002, 02:19: Message edited by: R-WEST ]

mbk is right.

What happens is the hammer block is rubbing on the forward side of the interlock, slowing down the fall of the block, or the interlock is still slightly engaged under the mating surface on the hammer block. Sometimes it slows it down too much, and it won't fire. Other times, as Mike indicated, the barrel is closed just enough more that the locking bolts engage just a tad father, rotating the interlock a tad farther also, and giving just enough clearance for the block to drop just fast enough that the hammer can reach the firing pin with enough energy left to fire the primer.

BUT, in marginal situations like this, the block may drop enough to let it fire, even though in actuality the hammer is probably knicking the top of the block most every time.... just not hard enough to prevent it from firing every time.

YOU MUST have adequate engagement of the locking bolts, period!

Ink the tops of the locking bolts.

Open and close an EMPTY barrel a couple times, then see how far forward the ink has been marred on top by the locking table. It must be marred to a point about 1/32" forward of the "U" notch in the locking bolts. If it isn't, then the bolts have not traveled into the frame far enough to rotate the interlock far enough...... etc.

You can do the ink test with a loaded round also if you are not satisfied that the case sticking out is interfering with lock up.

No matter what, the locking bolts must engage the frame far enough.

Its like the latch on your car door or car hood. It may be latched enough that it won't open, but may still be ajar and not latched all the way.

Some day, maybe, I can come up with some kind of schematic to show this better. It is all there inside the frame to be observed, but you have to have your thinking cap on to see it.

Hang in there. It took me a long time to figure the thing out myself, and I did not have anyone explaining it step by step. You guys have a leg up.

Mike

After thought.

I went for a long time working on barrels before being forced into understanding the frame purely out of self defense 1) to make my barrels fire in the first place, and 2) to pull shooters out of the fire and save barrels from a reincarnation as tomato stakes...... when all it was was simply the height of the locking bolts relative to the height of the locking table in the frame or the chamber not deep enough to let the barrel close all the way on a loaded round.

After I did my part in the shop, if a problem cropped up, it was nearly always due to reloaders not bumping shoulders back so the case fit the chamber shoulder to breech face dimension.

Failure to understand the basics has been the cause for more people leaving the Contender system than you can imagine.... unless you have come to that point yourself in frustration. Then it is easy to see why so many people "used to have a Contender."

Mike

Ref.
Mike - Thanks for the info; I posted your data at another site (ReloadBench.com), as well, with due credit to you.

R-WEST

Please do post this everywhere you can. Save it in notepad or whatever and keep it on the desktop or wherever else it is handy.

Many of you have gotten the idea pretty well and are doing a good job of explaining it to others, which really helps a lot in the overall effort.

I'd rather be talking about different things. But the fact remains there is a lot of work to be done helping folks with problems like this, as old and chronic as the problem is.

Thanks for giving credit for the source. That is all I ask if you are copying what I have written.

Thanks again.

Mike

Maybe I should finally do my homework and follow Mike`s instructions .....? I went shooting last night and had another experience with my Contender, my 7-30 Waters Imp. barrel would not lock unless I slammed it close , after the 5 shot I quit and switched to my 375 Winchester barrel , brand new , same thing ?????? I figured the problem was/is with the frame , I took it apart again tried the bolt in all the holes ( had enough play for 2 guns , damn!)put it together again and it locked ! Now , the 375 Win. is a straight case with no shoulder at all , headspace is only at the rim , what if I had (I was thinking about this misfire topic) misfires with a case like that ?

Jurgen,
For misfires on a straight wall case, first I'd probably check for good locking lug engagement as Mike B. describes above. I have had a couple that did need to be stoned down. After that make sure the bullet is not seated out too far (not likely on a factory barrel) too where the bullet jambs the rifling. Also the chamber to case fit can cause the problem. A case that headspaces on the mouth which has been trimmed too short may slide into the chamber too far to where the firing pin can't get solid contact with the primer. I do not know how common this next problem is but I just had it happen with a .45 win mag barrel that I traded for. The chamber is too SHORT. The manuals that I have give the "trim to" case length as 1.188" - 1.190", for an empty case to chamber a hair above flush in this barrel it has to be trimmed to 1.183" MAXIMUM. If not, no sure lock-up and I get misfires, I proved that. I'm guessing this is why I got a virtually new "pristine" barrel in the trade. It was probably a real headache to the original owner, especially if he tried to shoot factory ammo. It now shoots very exceptional with proper length cases. Thats half the fun of a T/C they give you many options to shoot and balence that with an equal number of oppertunities to screw up.

Mike