Chambering a Panda

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gzig5

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Getting ready to chamber a new Krieger in 22BR for my new to me Panda. The instructions on Kelby's site state the following "When chambering for a Panda, Kodiak or Grizzly barrel cut the tenon 1.0625” in diameter by 1.115” for a cone bolt action or 0.980” for a flat bolt action. For an Atlas barrel cut the tenon 1.0625” in diameter by 0.692” for a cone bolt action or 0.557” for a flat bolt action. It is recommended that the first 0.110“ from the rear of the barrel be turned to 0.966” diameter. Leave the rear end of the barrel square for now."
What's the purpose of turning .110" down to 0.996"? Is that a thread relief up at the barrel shoulder, or a relief at the end of the barrel for some reason? It's not clear to me, obviously.
 
They are talking about at the start of the thread next to the cone not at the shoulder end of the thread. This gives a little neater appearing start of the thread than just having it start at the end of the tenon. If you cut a thread relief at the barrel shoulder then .966" would be way more than necessary as the minor diameter of a 1 1/16" diameter thread is a few thousandths over 1" in diameter. I've threaded barrels with a relief there or without it. It doesn't make much difference one way or the other.
 
I prefer a nice bevel.

That .966 is the double depth of a 18 tpi 60 degree V Thread.

By the way, I feel safe in saying that most Gunsmiths turn that tenon to 1.057/1.058.
 
Thank you gentlemen, that works for me. I was a bit surprised at the recommendation for the tenon to be the full 1.0625, I usually go 5-6 thou less than "nominal". Could the action thread be a bit oversize on purpose so it will accept that "larger" major dia? I haven't pulled the current barrel yet, so it will be interesting to see how it was done.
 
Being a rookie I trusted the published tenon dimensions. When I re-barreled my brother's 30 BR, he provided the tenon print from the manufacturer. Using the jigs loaned to me by this guy Butch, who does not claim to be a gunsmith, took measurements of the tenon and headspace off the old barrel. Noted the difference in the pitch diameters, the old barrel measured 1.016, whereas the print called for 1.023 - 1.024. The old barrel was chambered by the action manufacturer, I thought maybe he just purposely cut the PD that much smaller, so I went with the published print, hoping it will be a nice fit. Got the tenon done, no go, the barrel did not screw in.

Back to the phone with Butch, he suggested duplicate the old barrel
The barrel went back to the lathe, indicated it and chased the thread, cut the thread to 1.016 PD, life was good.

Question. To what PD do you guys cut the threads on 1 1/16 x 18?

Why the discrepancy in the published PD and actual to where the action would not even screw in with the published PD?
 

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Jackie,

Thank you.

I was just curious, not being able to test fit the receiver to the tenon, I relied on my PD micrometer with the proper tips for the pitch to establish the proper dimension for the action to screw on. Remember this the first bolt gun I ever chambered, I thought I was doing the right thing by using the micrometer. The education continuous.
 
NezRongero said:
Being a rookie I trusted the published tenon dimensions. When I re-barreled my brother's 30 BR, he provided the tenon print from the manufacturer. Using the jigs loaned to me by this guy Butch, who does not claim to be a gunsmith, took measurements of the tenon and headspace off the old barrel. Noted the difference in the pitch diameters, the old barrel measured 1.016, whereas the print called for 1.023 - 1.024. The old barrel was chambered by the action manufacturer, I thought maybe he just purposely cut the PD that much smaller, so I went with the published print, hoping it will be a nice fit. Got the tenon done, no go, the barrel did not screw in.

Back to the phone with Butch, he suggested duplicate the old barrel
The barrel went back to the lathe, indicated it and chased the thread, cut the thread to 1.016 PD, life was good.

Question. To what PD do you guys cut the threads on 1 1/16 x 18?

Why the discrepancy in the published PD and actual to where the action would not even screw in with the published PD?
Click to expand...

Curious, what type of cutter and do you feed the cutter straight in or with the compound. If with the compound, what's it set on? Has the cutter ever been sharpened?
 
Maybe you just got

a small one.

I do alot of panda's for different guys and have bbl specs for each. I looked through my computer files and the smallest PD I show is 1.021 Thats looking at 15 different actions.

I know my pitch mic is right on. I have them qualified with certs every other year.

Over the years of doing various brands of actions (BR actions) they will vary quite alot. It's just a crap shoot on the first bbl. I've seen undersized, oversized, even tapered. I have one on file that the PD is 1.023 at the action face and tapers to 1.014 at the back! The actions shoots great but it's just one of those things you don't find until you try spinning the bbl on.
Another good reason to keep good notes!!

Bbl threading aids sometimes work and sometimes not. Learned that along time ago. Had one action maker tell me" if our bbl threading aid screws on it will fit any action we make of that type" Found out that wasn't true.
Don't you just love pulling a bbl out of the lathe and it won't fit!

Richard Brensing
 
Richard said:
a small one.

I do alot of panda's for different guys and have bbl specs for each. I looked through my computer files and the smallest PD I show is 1.021 Thats looking at 15 different actions.

I know my pitch mic is right on. I have them qualified with certs every other year.

Over the years of doing various brands of actions (BR actions) they will vary quite alot. It's just a crap shoot on the first bbl. I've seen undersized, oversized, even tapered. I have one on file that the PD is 1.023 at the action face and tapers to 1.014 at the back! The actions shoots great but it's just one of those things you don't find until you try spinning the bbl on.
Another good reason to keep good notes!!

Bbl threading aids sometimes work and sometimes not. Learned that along time ago. Had one action maker tell me" if our bbl threading aid screws on it will fit any action we make of that type" Found out that wasn't true.
Don't you just love pulling a bbl out of the lathe and it won't fit!

Richard Brensing
Click to expand...

Richard, I have a Stiller Diamond Back, 1.0625 18 tpi tenon, which is a direct match to a Panda. But a barrel fit for it or a Panda will not fit into the 1.0625 18tpi Bat Neuvo I just installed a barrel on.

The biggest variations I experience with Actions was the early Farleys. Their "1 1/16 16 tpi tenon" was sort of a "suggestion".:rolleyes:
 
I have a couple Pandas and bought a Borden with the spacer to be able to test barrels
The 1.060 I had been using for the pandas was to tight for the Borden
I've started making them all 1.057
 
I think the melonite has something to do with the tighter fit. Both of my coated actions have loosened up after a few barrels. That feeling of getting tighter as you screw the barrel on makes the pucker factor go up considerably.
Joe Hynes
 
liljoe said:
I think the melonite has something to do with the tighter fit. Both of my coated actions have loosened up after a few barrels. That feeling of getting tighter as you screw the barrel on makes the pucker factor go up considerably.
Joe Hynes
Click to expand...

No, Melonite is not a coating and does not increase dimensions.
 
liljoe said:
I think the melonite has something to do with the tighter fit. Both of my coated actions have loosened up after a few barrels. That feeling of getting tighter as you screw the barrel on makes the pucker factor go up considerably.
Joe Hynes
Click to expand...

More than likely you are cutting your threads in too few coarse steps. When there is no allowance for failure, most cut lathe threads with the least passes possible. Doing that you are leaving a thread which has sharp edge steps on the back of the thread. That side of the thread is the most important, and all that pretty, shinny from the rear of the barrel and the front of the action are just clearance. Every time you install and tighten a barrel and remove it, that stepped thread chews away at the action thread.

Cutter angle, grind, tool angle, tool height, rigidity, in-feed tool angle , number of passes, number of cleanup, spring passes. and about a dozen more, if I really wanted to list them all.

Single point threads are not the holy grail, especially when most learned how simple it is from the pros available anywhere on the WWW.
 
TRA said:
More than likely you are cutting your threads in too few coarse steps. When there is no allowance for failure, most cut lathe threads with the least passes possible. ......


Single point threads are not the holy grail, especially when most learned how simple it is from the pros available anywhere on the WWW.
Click to expand...

Something to be aware of too is that on most lathes while on the cross slide dials the graduations move the tool half of the indicated amount while the compound dial moves the tool the actual indicated amount.

i.e. moving the cross slide dial 0.010" takes 0.010" off the diameter while moving the compound dial 0.010" takes 0.020" off the diameter.

.


.
 
Tim Singleton said:
I have a couple Pandas and bought a Borden with the spacer to be able to test barrels
The 1.060 I had been using for the pandas was to tight for the Borden
I've started making them all 1.057
Click to expand...

Remember too you only want an unthreaded diameter that is about 80% of what a sharp thread diameter would be. Look on most thread gages and they give the double depth of the thread as 80%.


.
 
Well I pulled the old barrel off and found a couple interesting things. It is right at 1.061 / .062 for the major dia, but it was a very smooth fit. The recess at the end of the action is 1.062 and you can see the OD dia of the thread cut into it so it would seem that this action would accept a full 1 1/16th thread. I've not measured over wires yet, but I will. The tenon is .020 longer than recommended, but the cone is deeper from the end about the same amount. Not sure why it would be done that way but the bolt nose clearance is maintained and the only thing you can see is there is essentially no flat at the OD of the cone. I think I will stick with the recommended dimensions, other than the thread major dia.
I had my barrel dialed in but pulled it to make a sleeve to measure the headspace with as well as a bronze "wedding ring" with 1/8" diameter radius to go over the barrel shank for the four adjustment screws to bear on. I didn't like the feel of the copper wire I was using, squishing under the screws as tightened up. Now I think I have all the tools made up, including a reamer mic and reamer pusher so time to dial it back in and get it done.
 
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