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Starting a rebarrel
- Thread starter cdhknives
- Start date
- Joined
- Apr 23, 2018
- Messages
- 7,043
Using the steady to support your work is good, but could you get it closer to the headstock? Then you would want to dial everything in with the 4-jaw.
- Joined
- Apr 12, 2013
- Messages
- 560
I only had the one piece of stock (1018CRS rod) that was a reasonable size and didn't want to cut it. If I buggered it up I still had enough to cut back and retry, if I cut it to proper length I had no backup. In addition my 4 jaw is hard to work with, one of the jaws has a wrong size adjustment screw that is slightly loose and that makes it very hard to dial in and keep it there. Therefore I try to run between centers wherever possible, and with a rod for a mandrel a driving chuck and dog seems the best option...
- Joined
- Feb 5, 2018
- Messages
- 643
Why does the cone look so deep or is it the picture?
- Joined
- Apr 12, 2013
- Messages
- 560
I think the cone looks deep because the chamber is not yet reamed. Once the larger opening of the chamber is in place it will look more normal. When I was comparing the cone angle to the factory barrel I had trouble with the same view...
- Joined
- Oct 29, 2014
- Messages
- 352
Allow me to be caption obvious for a moment but I thinks its worth a mention. Be certain that the case head is properly supported by the chamber walls when you have your tenon all set up. For a simple check you can section the back of a piece of brass and insert it into the chamber for a visual inspection. Excessive bolt nose clearance or extractor clearance can cause case head failures.
- Joined
- Apr 12, 2013
- Messages
- 560
Understood. I have the old barrel for comparison, and the tenon I ended up with is about .020 longer even with the facing off a bit of the receiver. The stripped bolt still closes with no contact on a hand tight fit up.
The cone angles match as close as I am able to set up and measure given the very tight spaces. I also took the smallest angle (41 degrees) from everything I found/measured/was told for the cone (lots of contradictory info out there on the M70!!!) as I can always increase it later. I also have go and nogo gauges to verify the chamber. At this point I fully expect less exposed brass than before but I fully intend to compare before final assembly.
The cone angles match as close as I am able to set up and measure given the very tight spaces. I also took the smallest angle (41 degrees) from everything I found/measured/was told for the cone (lots of contradictory info out there on the M70!!!) as I can always increase it later. I also have go and nogo gauges to verify the chamber. At this point I fully expect less exposed brass than before but I fully intend to compare before final assembly.
- Joined
- Apr 12, 2013
- Messages
- 560
Got the chamber about 1/3 in. Using a 7/16 drill (MT2 shank in the tailstock) to take about .3" at a time (per the Hinnart book suggestion to save reamer wear) then the reamer till the shoulder is cutting fully. Back and forth. Question: I am cutting about .05" depth then withdrawing and clearing chips. Too much/little or about right? I brush the chips out of the reamer with a small brass brush, blow the chips out the barrel, then squirt cutting oil in the barrle and on the reamer. Repeat. Many tedious times. No I don't have a flush attachment and don't have a big enough headstock bore to even cosnider chambering through the headstock, so the muzzle (the '1.5 inches to be cut off at the end of the process' part) is in the chuck jaws.
- Joined
- Apr 12, 2013
- Messages
- 560
With regards to tenon length, since there is no easy way to measure bolt lug to receiver face on a tapered lug...the taper on the front of the lug vs the flat of a depth gauge...I resorted to layers of tape. 3 layers of blue painters tape had the first sign of resistance to bolt close, 4 layers was definate resistance. 4 layers measures .010", so call it .0075" clearance with the receiver hand tight. A bit more than the .005" recommended, but much tighter than the factory bbl! I don't think I am going to try and take out that last .0025"!
