RG45-70 fail to fire/light hammer strike/no strike

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RG45-70 fail to fire/light hammer strike/no strike

Postby Arroyoshark » 11 Apr 2016 16

I have picked up the topic, apparently long after original investigations by Tuco Ramirez and Centaur in another thread. I am posting this in the Rio Grande Sub-forum, because, in this case those who might be experiencing these issues might look here first.

I was quite discouraged a couple years ago after I picked up an RG45-70, because I had a lot of issues with both light primer strikes and the hammer failing to fall completely to strike the firing pin. I set this rifle to the side until I had more time to deal with it. Now, unfortunately, or fortunately, the Rio Grande series is out of production. I think that for the most part it is an arm that was plagued, if not sunk, by manufacturing intolerances. Some examples work wonderfully, as experienced by Ranch Dog's very early model. Others seem to be more hit or miss for perhaps a number of reasons. I have followed a lot of comments and the gun smithing work on the Rio Grande by Tuco Ramerez as well as Centaur. Centaur has not posted here for over a year, so I do not know the final outcome of his work.

Here is what I have found in taking this gun down and observing the interaction of particular parts.

First, Head space and bolt slop:

I chambered rounds loaded with R-P brass and rounds loaded with trimmed Starline Brass, and the bolt lockup was good. I don't have any worries here.

Second, the firing pin:
I discovered that the firing pin on my example seemed very tight, mostly stuck. Sometimes it took three times to get a round to fire. I disassembled the bolt, unscrewing the pin for the rear firing pin piece, then driving out the retaining pin for the forward firing pin part. When I removed the firing pin, I observed that the slot in the firing pin for the retaining pin was galled, indicating a lot of interference between the retaining pin and the slot in the firing pin. In order to loosen things up a bit, I took a file, then a stone, to relieve the slot so the firing pin did not actually contact the retaining pin.

Here is a part of the exploded diagram for the Rio Grande Bolt:

Rio_Grande_exploded bolt.jpg


Note that within the bolt (#17) is the firing pin (#21), with retaining pin slot next to the part number and the retaining pin (#74) that was interfering with movement of firing pin. I should add that to remove the extractor, in order to remove the retaining pin, place bolt in a padded vise, spread a needle nose pliers so tips of jaws contact both sides of the extractor and give it a tap. The extractor should come flying right off (literally). Keep an eye on it !

After a few iterations filing away slight bits of material from firing pin slot, and then re-assembling the firing pin in the bolt and installing the retaining pin, I achieved a firing pin that moved back and forth on its own when I tipped the bolt up or down. I re-sassembled the rear portion and observed that there was no interference with the rearward portion of the firing pin and the forward pin. I could freely push both parts forward, and the cocking lever would easily push the firing pin back in the bolt for next firing. The smoothness of the firing pin movement at least duplicated the feel of the firing pin in an older Marlin 1894 that has no firing issues.

I might also mention that a previous poster on this topic, "ozarki" felt the gremlin in his rifle was the flat spring (part #67) that pushes the rearward portion of firing pin down. I inspected it, found nothing out of sorts. When the bolt was fully assembled, I could still shake the firing pin(s) back and forth with relative ease. The use of the flat spring seems typically Marlin as well.

After a trip to the range to test the modification, I had no more failure to fire. I had no instances of light primer strikes. Indicates to me that the Rio Grande hammer spring is sufficient and that the firing pin moves freely. It also confirmed that on my RG example that the bolt lockup did not interfere with the rearward portion of the firing pin sufficiently striking the forward firing pin.

All this was comforting to me. I did not relish whittling on the other action parts as this could affect action timing and function, possibly undesirably. I might mention, at this point, that the trigger on my RG is delightful, right out of the box. I did thoroughly clean the arm when brand new, but the trigger is a light 3.5 lb. release, with perhaps only a barely detectable amount of initial creep. I would not want for a better lever action trigger.

Third, Hammer drop:

What was disturbing, back out at the range, was that I did continue to experience the hammer stopping several times at near the half cock position, causing a failure to fire.

I reviewed the modifications done by Centaur in this thread.

For reference,
viewtopic.php?f=44&t=2206&start=40

I would like to raise a red flag to the modifications he made to the hammer.

If you remove the cross bolt safety from the frame and peer into the hole for the safety, then operate the hammer, you will find that the part of the hammer that Centaur whittled away does not actually touch the receiver frame. That is the part that engages the interference portion of the cross-bolt safety. If you whittle much material from the hammer, it will compromise the hammer blocking safety. Just a heads up here ! I would not do this. I think Centaur was close to the problem, but he was going after the wrong part as I discovered.


Fourth, Cross-Bolt Safety:

This little part turned out to be a smoking gun !

Out at the range, I noticed that when the hammer was captured at the half cock position, when the trigger was pulled, it was due to some very minor interference with the safety. Seems the safety moved back and forth on my Rio Grande way too easily. The recoil, plus cycling the lever often caused the safety to move to right a slight amount, enough to block the hammer. If I pushed the safety to left before each shot, the round would go off - not a solution in my mind.

To test this I removed the stock in order to remove the tension screw, spring and ball detent for the safety, so I could remove the safety to the right. The first thing I noticed was that the tension screw was backed out a fair amount. This apparently significantly reduced the tension on the ball detent allowing some free movement of the cross bolt safety. I also discovered that tightening the tension screw down tight, resulted in making the cross bolt safety impossible to push back and forth. It was locked in place.

Here is pic of the safety detent system (borrowed from Beartooth Mercantile site)

3_large.jpg



4_large.jpg


I completely removed the tension screw and ball detent, and the safety. Once more I tried some rounds. What I discovered was no hammer drop failures, no rounds that did not go off. In reviewing the symptoms that several other RG owners experienced, the failure of the hammer to fully drop when trigger pulled, and the fact it fell to nearly half cock position, supports in my mind, that either the cross-bolt safety is not manufactured to correct tolerances, and/or the tension screw backs out under extended firings, resulting in not enough pressure in the ball detent to hold the safety in the fire position.

I have used Winchesters with conventional half-cock safety positions for decades, so the cross-bolt safety seems like a lawyered design feature. I decided to order a safety delete from Beartooth Mercantile. I did not care to have the saddle ring feature, so was going to order the basic delete part. The blued ones are out of stock at moment, and I didn't want a stainless part on my blued gun. I am off to Ace Hardware to get some 5/16 carbon steel rod that I can cut and machine to correct dimension to fit. I don't have a lathe, so will see if I can do what's needed with my drill press. I will post a pic of the finished part .... if I am successful.

So, to bring some closure to this, the Rossi Rio Grande is not difficult to disassemble or put back together. I would advise much caution in doing any whittling on parts, at least until there is some observed verification that it is not something else happening with the rifle. If anyone is having occurrences of light primer strikes or failure to fire a round, and it is not an ammo issue, it is worth disassembling the bolt and firing pin to check for binding with the retention pin for the firing pin.

If you experience hammer falling problems when pulling the trigger, check for interference with the cross bolt safety. Pull the butt stock off and examine whether the tension screw has backed out too far.

This seems to be an older issue, but those still playing with their Rio Grande rifles might benefit from this.
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby GasGuzzler » 11 Apr 2016 17

Awesome. Thanks for your time in documentation.
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby Ranch Dog » 11 Apr 2016 21

Yes, great job with the detective work and the writing! Thanks!
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby Arroyoshark » 05 Sep 2016 15

THIS IS A FOLLOW-UP TO MY ORIGINAL POSTING, WITH PROGRESS TO DATE. (FOR WHAT EVER IT'S WORTH)


Wow, time passes quickly. Finally got around to finishing what I started. I removed the cross-bolt safety and the Rio Grande's reliability went up. When the safety was removed, it left a hole on both sides of the receiver, making gun look unfinished.

For clarification and review, the cross-bolt safety, when pushed to right engages an interference surface that prevents the hammer from striking the firing pin when the trigger is pulled. The problem I was having is that the safety would move just a little to right on firing which was enough to interrupt the hammer fall, causing rifle not to fire. As an aside, I've since come across several postings on other forums that indicate a similar thing happens with newer marlin levers. It was suggested that a tight fitting o-ring could be fit over the left (red) side of safety preventing it from moving to right. So apparently Rossi has successfully cloned the bad aspects of the marlin 336 as well.

Here is a photo of the hole in receiver with hammer cocked - note it is a round hole.

IMG_20160904_154903.jpg


With the hammer down, there is a small tang now visible in the bore for the cross bolt safety. This is the surface that rests on the safety when it is engaged.

IMG_20160904_154817.jpg


I decided to fabricate a plug, from aluminum rod to fit in the hole and not have any surface that could interfere with the hammer. I selected aluminum rod as a test bed for this, and may later fabricate a plug from steel rod. In any case the old safety is not a uniform diameter across its length. It mic'd approx. .314" on the right (green) side, and .299" on the left end. The width of the receiver measured 1.025".

I cut a piece of rod 1.027" long and chucked into my low ball lathe to turn down to size. I don't have a lathe, so used a De Walt 3/8 variable speed drill held in a vise. I then used combination of diamond file and stone to achieve the desired diameters of .315" on right side and .300" on the left side, for a snug fit. Here is the rod chucked into my drill.

IMG_20160901_125351292_HDR.jpg



After getting the rod to correct diameters, I filed a notch approximately half the rod diameter into the center, making sure the width of the notch was wide enough not to interfere with the hammer. Here is the hand formed part next to the original cross bolt safety.

IMG_20160904_124149093.jpg


Here is the part after I blackened it.

IMG_20160904_134226170.jpg


I installed the plug into the receiver, and secured it with the tiny ball bearing, spring and lock screw that is used with the cross bolt safety. In this case I tightened the screw down to prevent any movement. I had filed a V-groove in the plug for the ball bearing to seat against.
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Last edited by Arroyoshark on 05 Sep 2016 16, edited 1 time in total.
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby Arroyoshark » 05 Sep 2016 16

FOLLOW UP TO ORIGINAL POSTING (FOR WHAT EVER IT'S WORTH)

The final fit was pretty danged close. I finish fitted the final length dimension, and made it smooth on both ends. The piece is a snug fit in the receiver, which is good. I did not file any fake screw slots into the ends of the plugs. At the original Rossi price point, this is just a utilitarian piece.

I know I could have ordered up the aftermarket part from an online source (for a Marlin) and just fitted it to the Rossi, but had wanted to challenge my need to tinker and see if I could do it myself.

Have to wait and see if the aluminum plug holds up to use, but can't yet figure out why it shouldn't.


IMG_20160904_154652.jpg




IMG_20160904_153459089.jpg


Now, back to the +guns
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby Ranch Dog » 05 Sep 2016 16

That is really great work, thanks for posting!
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby GasGuzzler » 05 Sep 2016 17

Nice. I like fixing stuff like that too.
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby Steve-R » 06 Sep 2016 18

Ranch Dog wrote:That is really great work, thanks for posting!

+1
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby klr » 06 Sep 2016 19

Nice work!
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Re: RG45-70 fail to fire/light hammer strike/no strike

Postby Archer » 07 Sep 2016 14

The only potential issue I see is how to keep it oriented so that it does NOT in any way contact the hammer.
IF you've got that worked out, other than a more or less interference fit then it sounds good to go.
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