Author Topic: Transfer bar and FTF (Read 6704 times)

gcrank1 · « **on:** February 16, 2011, 07:19:55 AM »

It finally got me!; FTF and light strikes. So I dug deeper............Perhaps this will help someone else.
When it occurs I have continued holding the trigger back to be able to inspect the t-bar function. With it unloaded and cocked, checking the firing pin protrusion with just the transfer bar pushed forward it has a good way to go (fully extended .090 which I DONT want all of!), with the hammer lowered to do the same as when fired, it is noticably less at .042 (.050-.055 is not uncommon).
Looking closer, it is obvious that the top portion of the hammer is peening the top lip of the action (a shiny spot is up there); so the action contact of the hammer nose is arresting the hammer fall short of fully depressing the transfer bar/firing pin far enough, thus light strikes.
I could drop the hammer, jig it up and grind the top contacting tip area flat and square on the mill; not too bad a job, but it can be done on the gun too (with care!).

But this does bring up the question (perhaps Brian of H&R will chime in), since the hammer nose of all the Handi's that I have looked at show no sign of having been 'dressed' to final fit for proper firing pin protrusion, does the factory depend upon different transfer bars of varying thickness to achieve this?or different length f-pins? If so, are they 'available'?

quickdtoo · « **Reply #1 on:** February 16, 2011, 08:34:59 AM »

This has been discussed many times and on Fred's website in the FAQs, the only way to check functional pin protrusion is with trigger pulled and held back while lowering the hammer manually to the rest position, then measure the pin protrusion. The easiest way to increase pin travel is to reface the tip of the hammer where it rests against the frame, removing material from the frame is much harder to do, and the hammer can be replaced easily if a mistake is made, Fred states that removing material from the hammer face can cause the t-bar to jam, but I've done a couple dozen and never had a problem yet.

One caution on increasing pin travel no matter how you do it is to make sure the hammer isn't resting against the pin causing it to stick thru the standing breech slightly, hammers and frames have a lot of dimensional differences, I've had the hammer make contact with the pin directly on two different frames, so beware, this negates the safety feature of the transfer bar if the hammer drops accidentally, not too likely since it only touches lightly, but a more likely consequence is the barrel damaging the protruding pin when opening and closing the action.

Tim

gcrank1 · « **Reply #2 on:** February 16, 2011, 09:11:21 AM »

And it will drag across the primer and case before it hits the ejector/extractor; very obvious.
You are right that the interplay of parts in even a simple action, such as these, is more complicated than might be assumed.
As Ive said in the past, before removing any metal (on any part) make sure you know that is the right place to do it (and do it on the cheapest, most easily replaced part if possible).

quickdtoo · « **Reply #3 on:** February 16, 2011, 09:55:20 AM »

Quote from: gcrank1 on February 16, 2011, 09:11:21 AM

And it will drag across the primer and case before it hits the ejector/extractor; very obvious.

That's not necessarily true, depends on how much pin protrudes of course, 1) if it's loaded and then only if the headspace is minimal, and 2) an ejector wipes the breech face hard every time the action is closed, some don't have much of a bevel on the bottom edge and will catch on the firing pin if it protrudes, same for extractors to a lesser degree, don't ask me how I learned that little tid bit!!

Tim

gcrank1 · « **Reply #4 on:** February 16, 2011, 10:15:02 AM »

Quick, have you ever measured the thickness of the transfer bars at the firing pin contact suface, or know someone who has? Im curious to find out what these are running at in the newer guns and how it relates to the incidence of FTFs.

quickdtoo · « **Reply #5 on:** February 16, 2011, 08:31:16 PM »

I measured three spare t-bars, the newest I just got from Numrich is .152" the other two are .150".

Tim

gcrank1 · « **Reply #6 on:** February 18, 2011, 02:14:48 PM »

The plot thickens (and yes, I have reviewed the FAQs).
I did measure the f-pin protrusion as indicated (I have a simple homemade plunger rig for this), had .042. I saw nothing wrong with increasing this to .050 as even those cartridges that went off well had lightish strikes.
Test fire one was fine, two didnt........hmmmmm; and Im sitting there with the trigger well back in the guard (and I had looked when it was cocked, the T-bar was fully up); I slowly let the trigger forward and 'no click', you know, the one you are supposed to get as the t-bar falls within the action after firing.
What this means is that ,even though consciously pulling the trigger fully to the rear in a brisk fashion, that the t-bar was falling out of place and perhaps only a bit of it made f-pin contact ?(thus light strikes). The t-bar seems to fall out of place so quickly that you cannot pull the trigger fast enough, and trying to is no good for shooting anyway.
This is apparently an internal t-bar malfunction requiring dissassembly and analysis. I see the 'tip' on the rivet for initial viewing.
More to come, Im sure........
BTW this is a post '08 rifle (CBA)

gcrank1 · « **Reply #7 on:** February 19, 2011, 02:04:26 PM »

There are two issues to consider if you have 'misfires' or complete FTF.
One is just inadequate f-pin protrusion, observable by consistent 'light strikes' that may or may not fire. You have to inspect each round for indent on each try, multiple hits may make it go off and also make the dent deeper. It is measureable and relatively easy to increase the f-pin protrusion as mentioned previously.
The other is more complicated. You may get ignition on some rounds, and they may show a decent indent, while others FTF and show very light strikes. There have been other t-bar malfunctions but in my case I believe that these are caused by the transfer-bar falling prematurely from the strike zone of the hammer/f-pin, perhaps only partially getting some hammer blow, but not enough as it slips off the lower beveled edge of the f-pin.
This is observable following the FTF if you still have the trigger fully pulled back. Hold it there and slowly draw the hammer back just a bit and you will see the t-bar is sitting below the F-pin.
I believe the reason it slips out of position is because the t-bar 'lock' (this may not be the official part name) is not holding the t-bar in place until after ignition. This 'lock' is an arm in the trigger assembly that rides on the trigger pivot pin and has a locating pin down on the left side of trigger body. The tip of this simple, stamped part, as fit from the factory, may not be quite correct.
Now, to find an 'unfit' one to compare and fit myself...........

quickdtoo · « **Reply #8 on:** February 19, 2011, 02:33:13 PM »

That part is called a trigger extension, Brownells is out of stock, but Numrich has it, it's likely the part that H&R "adjusts" when there are FTFs or light strikes, it was discussed at one time in the rimfire forum after a rash of Sportster misfires.

Tim

http://www.brownells.com/.aspx/pid=0/sid=676/schematicsdetail/SB2_Handi_Rifle_H_R_Ultra

http://www.gunpartscorp.com/catalog/Detail.aspx?pid=280780A&catid=3626

gcrank1 · « **Reply #9 on:** February 20, 2011, 10:16:05 AM »

Thanx Tim!
Update: I decided that I had nothing to lose; I took the 'trigger extension' to the anvil and, on the horn, cold forged it to lengthen it (the horn does this, not an anvil flat) a bit on the contacting tip end. That is, the end which contacts the transfer bar and locks it in place when you pull the trigger.
I made this whole operation easier by having a slave pin for the trigger group assembly and a pair of slip fit test pins to replace the small front trigger guard retaining pin and the thru pin for the trigger group proper (quick assembly/disassembly compared to the factory splined pins).
I know a half dozen shots is far from definative, but, 6 shots without a bobble after 50%+ FTF is very encouraging; enough for me to be confident that this is the culprit and I can fix it!
When I can get a couple 'virgin' parts I will test my theory that they need to be long enough to lock the t-bar right after the sear trips out of the hammer notch, and no shorter.

quickdtoo · « **Reply #10 on:** February 20, 2011, 10:20:57 AM »

That sounds like a real easy fix, good stuff for the FAQs, thanks!!

Tim

OR-E-Gun Bill · « **Reply #11 on:** February 20, 2011, 03:25:02 PM »

Just so I'm getting this right, the area of the trigger extension that you have lengthened a wee bit is the area shaded in red in this picture taken from H&R manual, correct?

Note: This illustration is not an accurate representation of modern Handi rifle receivers. It was used only to show the relative positions of lifter striker/transfer bar and trigger extension.

I've been fortunate to have never had the problem of FTF, so far, but it will be a good tip to try if it ever does happen.

Thanx,

Bill

gcrank1 · « **Reply #12 on:** February 21, 2011, 03:29:23 AM »

Just so! Though the picture and my actual part differ somewhat in shape (they may have used an old illustration of a previous t-bar) the contact area and function is as you see.
Do understand, VERY little lengthening is needed. I suspect it would be overkill to weld a blob out there and have to grind most of it back off.
Shimming the slop out of the assembly at the pivot pin may help too but its another piece to have to get the slave pin in and out of (probably supergluing the shim washer to the trigger ext. would be best), and make sure you dont make the trigger too tight.
BTW, with the trigger assembly out is a good time to spray flush the rest of the works and , using a needle oiler, lube up the hammer pivot, etc. I also like to put a little 'magic goo' on the hammer notch for the sear tip.

zoner · « **Reply #13 on:** February 21, 2011, 03:38:41 AM »

very good thread.....there'd been several reason's and fixes to the FTF issue, taking a little off the hammer to increase pin protrusion, installing the wolff hammer spring, etc. But i've always been a little suspicious of the trigger extension. Sounds like you are having some success by lengthening it. Did you measure before and after the mod? Wondering how much "length" you gained?

44 Man · « **Reply #14 on:** February 21, 2011, 04:37:37 AM »

I think knowing this would have saved me a lot of grief when I had this problem with my old Topper! Thanks! 44 Man

dangerranger · « **Reply #15 on:** February 21, 2011, 05:21:46 AM »

At the time I sent mine in to the mother ship, they said that they had a more effeciant transfer bar system.I had already replaced the hammer spring, cleaned and pollished the firing pin, and squared the frame and hammer to increase the firing pin protrusion. that was as far as I knew how. after all that I was still getting 50% failure to fire. according to UPS my rifle is due back today. we will see if the extention is what they have replaced. Im hopeing it is that simple. DR

gcrank1 · « **Reply #16 on:** February 21, 2011, 05:23:47 AM »

Thanx guys!
Z, I thought about measuring but did not since the piece is oddly shaped and would need a good fixed data point that was really repeatable, especially for only a few thou' change on a 'slanted' contact surface.
I considered the 'cause and effect' approach more meaningful as each FTF situation caused by this will need to be hand fit anyway.
Ideally (for me) a new, unfit tgr-ext. would be a tad too long to allow hammer trip, but its hard to say what length they are in the box of parts they assemble from.

gcrank1 · « **Reply #17 on:** February 21, 2011, 05:27:40 AM »

DR, the same effect could be achieved with a little thicker lug on the lifter portion of the t-bar (where the tgr-ext. contacts it, though that part is more expensive and troublesome to replace even for them). I am curious what your work order will indicate.

dangerranger · « **Reply #18 on:** February 21, 2011, 03:42:02 PM »

I just got the rifle back. took it out to the garage and fired ten primed cases with no missfires. H&Rs repair document says they replaced the striker/lifter,hammer, hammer spring, and trigger. it also says they adjusted timing, refit forend, and test fired. further down the page under the material used it says "H&R striker-original style". what happened to the "more effeciant" one? Not complaining tho, if it works Im happy. DR

gcrank1 · « **Reply #19 on:** February 21, 2011, 04:36:01 PM »

I wonder what would have happened if they would have just properly fit a trigger extension?
We will never know; glad it is working for you!
I am suspecting that the 'adjusted the timing' is possibly what I have been doing here.

dangerranger · « **Reply #20 on:** February 21, 2011, 07:16:28 PM »

I wonder if they do have several sizes? I cant see them grinding each to fit. DR

gcrank1 · « **Reply #21 on:** February 22, 2011, 05:22:51 AM »

On this one it was evident that some grinding had been done, I will make it a point to check every one when I take an action down! Next time you look at one you will see for sure just how chintzy a part this is for such a critical function.

gcrank1 · « **Reply #22 on:** March 05, 2011, 06:00:01 AM »

I was able to acquire some trigger extensions to compare, measure, swap for testing and function, etc. At this point I am getting better hold upward of the transfer bar and, with limited test rounds, am not having FTF.
With a little further inspection though, I note that the Firing Pin chamfer on the underside is considerable too, and typical of my several later actions. Combine this with the downward angle of the F-pin body through the standing breech and the rise of the T-bar Striker I can visualize the hammer fall hitting the Striker and somewhat 'squeezing' it down and out of contact onto that chamfer (like squeezing a watermelon seed till it flies off). I dont think the chamfer needs to be near what they make it; better would be the lower 1/3, not the 1/2, or more, that it is now.
But that is another set of trials.
For now, this trigger extension work has convinced me that this inexpensive and easily replace part may well fix a number of FTF syndrome rifles.
Make sure you have adequate F-pin protrusion too and it should go bang.

quickdtoo · « **Reply #23 on:** March 05, 2011, 06:06:06 AM »

Good work, thanks!!

Tim

Deerhunter#1 · « **Reply #24 on:** March 05, 2011, 08:10:14 AM »

Well I have a question as my receiver was sent in previously with a 243 ultra to be fit. When I received it back It was fine. I have since sent it in and received a 7.62 barrel and my first trip to the range was today with it and out of 30 rounds i had 3 ftf with the 7.62 with factory and reloads. I switched to the 243 and shot 30 with none. Can two barrels act different on the same receiver with ftf? Could the head spacing need adjusting. The groups were acceptable when it did fire about 1 1/2 for the 1st time being shot. Any thoughts?

quickdtoo · « **Reply #25 on:** March 05, 2011, 09:30:13 AM »

Off center pin strikes have been an issue, I've found a primer change can help with those, Rem and Fed primers seem to work the best, apparently less sensitive to off center pin strikes. But the 7.62x39 was discontinued due to misfires, so it could be a head space issue as well, the pin protrusion being suspect, check it and increase it a little and see if it helps.

Tim

Deerhunter#1 · « **Reply #26 on:** March 05, 2011, 09:43:06 AM »

Off center strike is a def. I have a noticable off center strike and am using cci primers. I looked at the strike of my 7-08 and it looks just as deep so I will try some other rem primers first. Hope that works dont feel like sending back again.

Slackdaddy · « **Reply #27 on:** September 29, 2011, 03:03:03 AM »

Gcrank1,
can you give a detailed description of "lengthening" the triger extension.
Not a blacksmith, debating building up with weld/grind,,
Could the lengthening be done on a 1" bolt shaft, as I don't have an anvil?

Many Thanks for taking the time with the detailed description of the problem/fix

Slack

gcrank1 · « **Reply #28 on:** September 29, 2011, 05:14:22 AM »

Any solid hunk o' steel (and a lot of bench vises have a short 'anvil' tail already on them) and a hammer does this job. It is good to match the hammer size to the work. A BIG hammer sure will flatten things, but usually what you are trying to do is move metal in certain directions (hot or cold shaping). That is what you are doing with this, drawing the end out a bit longer. So, think about how the stroke and direction of the hammer taps are moving the metal as you hold the piece mostly stationary. Move that striking head out that way as you hit, but dont do it with the hammer edge, use the face. Sometimes it helps to think about how material moves if it were modeling clay. Metal moves the same, only slower.
Also keep in mind that you want that tip of the extension to go longer, not wider and too flat.
Cold Forging 101.

Fred M · « **Reply #29 on:** October 01, 2011, 10:47:03 AM »

The most FTF comes from a worn out hammer spring, and a dirty and jammed up firing pin seat. On my website I have a complete write up how to make the FTF go away. A complete tuning of the transfer bar, hammer seat, and hammer itself. Remove and polish obvious points of friction. Dont't know what what benefit is achieved with the lengthening of the trigger extension. I am missing the point here.
Fred M.