Author Topic: 45/70 Latch shelf shim (Read 1094 times)

tcoggins · « **on:** August 19, 2012, 09:57:39 AM »

Gents - I have recently fitted a 45/70 barrel (purchased here) to my receiver. Had to shim the underlug to get a tight fit. This things locks up nice and tight at the breech. After putting about 40 rounds through it, I was having a tough time getting the scope zeroed. Scope rail is bedded to the barrel with Loctite, and the mounting screws are Loctited as well.

At any rate, yesterday while shooting, and getting terrible groups, I noticed that the release lever was all the way up when the action was closed. While I could not feel any up and down movement in the lockup, the fact that the release lever had no play in it told me that the lockup at the latch may have had some play in it.

I epoxied a .004" shim to the latch shelf, and stoned the shelf until I had a good contact (I smoked the shelf and stoned the surface very slowly). Now, I have about 1/16" movement in the release lever when the action is locked up.

Does it make sense that a little play at the latch would create accuracy issues? Based on the geometry, for every .001" of play at the latch, it could throw off the point of impact almost 1-1/2".

I welcome your thoughts on this.

Thanks.

Tim

quickdtoo · « **Reply #1 on:** August 19, 2012, 11:45:21 AM »

The latch release being loose doesn't really matter, it's position is indicative of latch engagement tho, as long as the barrel is tight with absolutely no looseness when locked you're good to go, ignor the latch release wiggles, it can wiggle freely and not affect accuracy as long as there is good latch engagement, it's just the way it's made, there's nothing to keep the release from moving, it's hinged on the pin and just has a cog that fits in a mating notch in the latch.

Tim

tcoggins · « **Reply #2 on:** August 19, 2012, 01:19:29 PM »

Tim - Thanks for the reply. My issue is not the looseness after shimming this, as all my other Handi's have looseness in the release lever. The issue was, before shimming, there was no looseness in the release lever, which indicated that the latch was all the way forward, but perhaps there was still some movement between the shelf and latch, which could cause some accuracy issues.

Does this make sense?

Thanks.

Tim

quickdtoo · « **Reply #3 on:** August 20, 2012, 04:16:35 AM »

Yes, if the release is all the way up and tight, the latch is at the end of it's travel just like it is when the barrel is removed, because of the geometry of the latch and shelf, that usually means the lock up isn't good and accuracy will suffer. Take a look at the FAQs barrel fitting pic of the latch index mark thru the inspection port which shows proper latch engagement, your shim fixed that.

Tim

gcrank1 · « **Reply #4 on:** August 26, 2012, 05:21:07 AM »

I cant help but wonder if the barrel lug should have been shimmed first?

tcoggins · « **Reply #5 on:** August 26, 2012, 12:50:50 PM »

Gcrank - The barrel underlug was shimmed first, but in the process of fitting the barrel to the receiver, I neglected to check the fit of the latch shelf. I have since shimmed the latch shelf(and have a bit of looseness in the release lever when closed), but have not had a chance to shoot this since then.

Is that what you posted about, or did I misunderstand (I worked all weekend, and am a bit frazzled)

Thanks.

Tim

gcrank1 · « **Reply #6 on:** August 26, 2012, 01:17:53 PM »

Yes, good that you shimmed the barrel lug in first. Have you since done the standing breech to barrel feeler gauge test? The latch, being a sliding taper to the latch shelf provides for lock up when the breech fit is correct and rarely need much, if any fitting. Did you take any material off the bottom of the breech end when fitting the barrel that would have made it seat deeper into the action, thus resulting the shelf to be too low?

cwlongshot · « **Reply #7 on:** August 26, 2012, 01:30:31 PM »

I have only had to shim one barrel like you have. (In about 50 or so H&R's)

I also epoxied the shim in place, but I chose to file more material away so I could attach a thicker piece of stock.

MOST barrels simply need stoning or gentle filing of the shelf. Sometimes I need to shim the hinge. But only once was the barrel so loose I needed to do as you have done.

I used a epoxy machinists use to affix carbide tips to drills. No brand name, its two "tubs" you mix together. MAN do they get hot!!! It is a 357 barrel and so fat its good. But its only seen a 100 or so shots thru it since the repair...

As long as you have the proper epoxy and you prepped the steel correctly, your shim should last. I chose to "wrap" the shelf simply to get more surface area for the epoxy to adhere too. I was concerned about the edge where the latch comes across the face to "work" against the shim.

CW

gcrank1 · « **Reply #8 on:** August 26, 2012, 01:43:12 PM »

Your pics are awsum, CW! (and your advice always good).

tcoggins · « **Reply #9 on:** August 26, 2012, 03:51:23 PM »

Gcrank - after fitting the barrel, I inserted a piece of aluminum foil (mic'd at .0005") in the breech area and closed the action. It was tight on the foil, which indicates a pretty tight lockup (I seem to recall H&R shoots for a maximum of .002" at the breech in a factory fitted barrel).

I am hoping that the shim takes care of the accuracy issue I was having. If it comes off, I will take the barrel to a local gunsmith and have him silver solder a shim on the shelf, then re-fit the shelf.

Thanks for all the input.

Tim

gcrank1 · « **Reply #10 on:** August 27, 2012, 06:17:42 AM »

Boy Tim, it sure sounds like you covered all the bases well. I wonder if a new latch might have just enough dimensional difference to make up what you are doing with a shim? Of course, all bets are off on that if the previous owner filed the shelf down.....
BTW, have you re-checked that clearance? (do so without any brass in there first, then again with).
If it is still good for headspace and lockup just work on your rest technique and it should come together.

quickdtoo · « **Reply #11 on:** August 27, 2012, 06:30:06 AM »

H&R makes 3 different latch lengths, Numrich sells em, I used the short one on the 50-140 barrel fitting rather than stoning the shelf, this was a new BC barrel that had never been fitted to a frame at the factory that I bought from Tim Looney when he worked for H&R/Marlin.

Tim

gcrank1 · « **Reply #12 on:** August 27, 2012, 06:37:26 AM »

WOW, 3 different latch lengths! First Ive heard of it; thats wonderful!

tcoggins · « **Reply #13 on:** August 27, 2012, 03:15:04 PM »

Tim - That sounds like a better idea than shimming the latch shelf. I will order one of each (since I don't know which one I have in my rifle). If the shim fails, I will have these as a backup.

It looks like the part numbers from Numrich are 275250, 275260B, and 275260C. Do those numbers sound correct?

Thank you.

Tim

quickdtoo · « **Reply #14 on:** August 28, 2012, 04:40:15 AM »

No, 1358720, 1358730(heavy) and 1358740(medium) are the numbers, but it appears 1358740 is no longer active, so it's only available from H&R, but being a restricted part, must be installed at the factory.

Tim

http://www.gunpartscorp.com/catalog/Detail.aspx?pid=1358720&filter=1358720

http://www.gunpartscorp.com/catalog/Detail.aspx?pid=1358730&filter=1358730

http://www.gunpartscorp.com/catalog/Detail.aspx?pid=1358740&filter=1358740

tcoggins · « **Reply #15 on:** August 28, 2012, 05:27:12 PM »

Tim - Thanks for the info.

Tim

tcoggins · « **Reply #16 on:** September 02, 2012, 08:18:23 AM »

Well, some good news and some bad news.

The good news - shimming the latch shelf tightened up the groups to about 2" at 100 yards (getting tighter from there is my issue, not the rifle's). The bad news - the shim came off.

I ordered some new latches from Numrich, hoping they will be bigger than the original. If not, I will have my gunsmith silver-solder a shim onto the shelf.

I thank you gentlemen for all the help and advice.

Tim

cwlongshot · « **Reply #17 on:** September 02, 2012, 12:39:03 PM »

Quote from: tcoggins on September 02, 2012, 08:18:23 AM

Well, some good news and some bad news.

The bad news - the shim came off.

I thank you gentlemen for all the help and advice.

Tim

Sorry to read this Tim... I was worried when I read it was on a single facet... But even then the prep of the parts could have been the reason for the failure... The metal needs a bit of a "tooth" to allow the "glue" to stick to. Also, both surfaces need to be 100% clean and oil free. I like to clean the parts with Acetone. This removes all finger oils or any such contaminates that may cause poor adheasion.

Hopefully one of the different size latches will fix you up!

CW

tcoggins · « **Reply #18 on:** September 03, 2012, 08:03:15 AM »

No worries. I believe if the larger latch does not fix the issue, my gunsmith can build up the latch shelf sufficient enough to get this to lock up.

Part of the fun of these rifles is the tinkering that goes on (as well as interacting with the fine folks here on Graybeard).

Thanks.

Tim

tcoggins · « **Reply #19 on:** September 04, 2012, 04:20:56 PM »

Latches came in the mail today. Largest one fit just fine and locks up with a little play left in the release lever.

Thanks again for all the great info.

Tim