Author Topic: Took the '76 to the range today. Had an issue and could use some help.  (Read 1311 times)

Offline Buckaroo Lou

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I took the '76 to the range today and was pleasantly surprised. The rifle will shoot. After figuring out how the rifle was shooting using the barrel sites that are original to the gun. I was able to shoot a 4-shot group of about three inches at 100 yards. Not bad for my aging eyes and the standard barrel sights. The rifle was dead on at 100 yards. I did not have to hold high as I thought I might. I did not flip the sight up in order to use the ladder but kept it folded down. Any farther distance shooting would require raising the ladder. I will probably try to find a better rear sight at some point.

I did find a situation with the factory ammunition that was/is puzzling. The factory rounds made with Jamison brass chamber ok until the very last 3/16". You must squeeze the lever unusually hard for the rifle to go into battery. I noticed after ejecting the spent round there was a little notch clipped out of the brass rim. I believe it is made by the rim locater extension (not sure if that is the correct terminology) on the bolt face. I measured the diameter of the case rim of the Jamison brass as compared to the Winchester 45-70 cases I had cut down and it is bigger. I did not have any difficulty chambering the reloads I had made using the cut down Winchester 45-70 brass thus no notches on the rim cases. I also noticed the firing pin strikes on the primers was off center a bit. Here are a couple of photos to show what I am talking about. Can anyone tell me how to correct this?

Can this happen if the extractor spring is too strong?
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Offline DJ

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What is the diameter of your Jamison rims and your reload rims?

Is this an original '76 or repro?

Off hand it looks like the Jamison rims are oversized for your gun.

--DJ

Offline Buckaroo Lou

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Sorry, I made another post not long ago about getting a new-to-me Chaparral 1876 rifle.

Yes, the Jamison case rim is larger than the Winchester brass 45-70 cases I cut down to the 45-60 length. The Winchester 45-70 case rim is .600 and the Jamison 45-60 case rim is around .680. They are Ten X rounds made for the 45-60 WCF. I would think they should chamber if they are made specifically for the 1876 rifle in 45-60 caliber.

Does anyone else shoot Ten X 45-60 ammo and if so have they encountered this problem? Or, is it another problem encountered with the Chaparral 1876 rifle. If it is a problem with the rifle can it be corrected? As I asked previously, can the ejector spring be too heavy pushing the case downward as the ejector engages the case rim causing the rim locater extension to bite into the case rim? Notice the firing pin strike is off center above where the bite is in the case rim also indicating as though the case might be being pushed downward.

I have trimmed the case rims on the Jamison rounds I shot to the same size as the Winchester 45-70 cases but have not yet loaded them or tried to chamber one. 
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Offline DJ

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The original 45-60  has a larger rim diameter than a .45-70 .  I suspect your '76 was set up to use reformed .45-70 cases (which are more plentiful and less expensive that .45-60), and the cartridge rim guide/locator is swaging that notch into your original-size cases.

Turning the rims should work.  You will probably want to avoid using the untrimmed oversize rims, because you're putting a lot of pressure on that part of your bolt by forcing it closed, and you risk breaking that guide piece off.

--DJ

Offline Coffinmaker

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 :)  Lou  ;)

It also appears the base of the case is oversize to the chamber (Bears witness marks).

Something is also not concentric between bolt face and chamber, I'm just no sure what.

PLUS ONE !!  and a HUGE PLUS ONE to DJ about running the Jamison Brass "as is."  something you have to remember . . . should you break something, there are NO replacement parts.  I'd personally suggest a return to re-formed 45-70 brass.

Play Safe

Offline Buckaroo Lou

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:)  Lou  ;)

It also appears the base of the case is oversize to the chamber (Bears witness marks).

Something is also not concentric between bolt face and chamber, I'm just no sure what.

Coffinmaker, I can insert one of the Jamison cartridges into the chamber all the way to the rim with ease. It is only as the bolt face engages the cartridge that the problem exists. I was loading them into the rifle this way as a single shot instead of loading them into the mag. tube because I was trying to determine what the problem was.
A man's true measure is found not in what he says but in what he does.

Offline Black River Smith

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Sorry, I made another post not long ago about getting a new-to-me Chaparral 1876 rifle.

Yes, the Jamison case rim is larger than the Winchester brass 45-70 cases I cut down to the 45-60 length. The Winchester 45-70 case rim is .600 and the Jamison 45-60 case rim is around .680. They are Ten X rounds made for the 45-60 WCF. I would think they should chamber if they are made specifically for the 1876 rifle in 45-60 caliber.

I have trimmed the case rims on the Jamison rounds I shot to the same size as the Winchester 45-70 cases but have not yet loaded them or tried to chamber one.

Buckaroo Lou,
First off, I have a Chaparral 45-60 and use 45-70 trimmed cases.  I have never encounter Ten X or Jamison brass.  The rim diameter that the Chaparral pamphlet lists is the same as the original Winchester -- 0.629".  That Jamison rim diameter is totally off or out of spec, if the 0.680" diameter is correct. If it is correct, then I can understand why your bolt and guide tab is making those dents.

You stated that you reduced the Jamison to the 45-70 diameter.  I hope you did not do all of them.  It would be nice to see if a piece cut to the proper 0.629 or slightly smaller, would function and eject better, than the extremely small diameter of the 45-70 brass.

My biggest issue with the Chaparral rifle, I bought/received was excessive extractor to bolt face gap.  I corrected that by installing a WinchesterBob 1876 extractor that resulted in a correct 0.060" gap.  But the ejection of brass was still weak because the tab was not pushing of the bottom on the rim.  As an experiment, I was able to extrude the rim diameter to 0.620" before the rim thickness of Winchester/Remington 45-70 brass got too thin.  These attempts still resulted in weak ejection from the rifle.  As I stated above, it would be nice to see if a piece cut to the proper 0.629 would function better.

While I was typing this reply it came to me -- Could your 'bolt guide tab' have been 'welded up' to give better contact, for use with the standard 45-70 rim diameter?  This would cause the dents in the Jamison brass even if the rim diameter was close to the original 0.629".  (EDITTED --- Sorry missed DJ posting comments before typing this line.)

Good luck with your rifle.  It sounds like it is a good shooter so far.
Black River Smith

Offline Trailrider

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An original M76 Winchester I had in .45-60 required .45-70 brass to have the rims thinned somewhat. (Sorry, I don't recall how much I had to thin them.) This was done from the front of the rim. I also seem to recall having to run the brass (after shortening) all the way into my .45-70 sizer die, so I couldn't use the shell holder, but use a bench vise, and then knocked the case out with a wooden dowel.  I had a similar problem with a .33 WCF. This only has to be done once.  I don't recall having to reduce the diameter of the brass (Winchester brand, IIRC).
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Offline Buckaroo Lou

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I turned all the Jamison brass rims down to .600 the same size as the Winchester 45-70 brass. They chamber and eject properly now. Anything larger and the rim guide would bite into the brass.

I have not pulled the bolt out of the rifle to examine it. I just haven't wanted to break the rifle down that far yet. I will some time in the future. Since trimming the rims down on the Jamison brass the rifle seems to be functioning ok now. I will go to the range again before too long and will report back then.

Thank you gentlemen for the assistance. You guys are the best!
A man's true measure is found not in what he says but in what he does.

Offline KenH

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Take a look at this thread:  https://www.cascity.com/forumhall/index.php?topic=64846.0 for an explantion of the problem.  The original Winchester bolt/ejector seems to be different than the replacement Uberti rifles.  I wound up turning the Jamison brass to Uberti size.

Here's a bit of info I typed up in my Project Rifle thread, look down toward the bottom of page:
https://www.cascity.com/forumhall/index.php?topic=64765.0

 

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