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Getting ready to cut my first Remington 700 breech. Check numbers please...

tonyben

Good morning! I'm moving forward with my Vietnam era M40 project and I'm getting ready to cut the barrel. Can you check my numbers?

I gauged my receiver and bolt dimensions yesterday. I created an Excel spreadsheet to calculate the barrel tenon specs and the bolt nose cutout specs as well as headspace gauge protrusion specs.
XZHCJrT.png


Tony.
 
I don't see why those numbers would work. When I did things on a manual machine I developed this process which eliminates some of the mental math.
HS minus 0.010" = tenon length I like the HS gage extending beyond the tenon if using a depth mic.
Counterbore depth equaled the distance from the bolt face to the end of the bolt nose. With the tenon being 0.010" short all I had to do is touch the barrel with my boring bar, set the travel indicator to the my bolt face depth number and go to zero. That automatically gave 0.010" end clearance. In my barrel log books there are only 4 numbers; HS, tenon length, CB depth and thread specs if not standard.
 
tonyben said:
Did you mean to say "wouldn't work"? As-in my numbers do work as posted?

I was going to use 0.005" of clearance for all the bolt to tenon/breech surfaces. Should I bump it to 0.010"?
Click to expand...
Yes sorry
I like a little more clearance than some. Everything has a natural resting place/state. Give it enough room to find that.
 
Okay, I opened up the formula for a 0.011" gap (should shrink 0.001" when the barrel is torqued equalling a 0.010" gap) and that changed my headspace protrusion from 0.001" recessed to 0.003" protruding.
 
Assuming you're using a factory M700, did you true the receiver ring and check lugs contact before taking your measurements?
 
tobnpr said:
Assuming you're using a factory M700, did you true the receiver ring and check lugs contact before taking your measurements?
Click to expand...
Pretty sure he did all that. Documented in his previous thread.

Post in thread 'First Remington 700 build. Do nothing at all, true the face or full blueprint?'

IMG_9750.jpeg


IMG_9751.jpeg

The barrel should be back from black oxide tomorrow. I also bought a 1/4” thick PTG ground lug and was able to throw it in with the batch to have it black oxide as well.

In the meantime, I jigged up the action and got it aligned. The face only had 0.001” runout and I gave it a skim pass. I ran my dial indicator over the threads and there’s about 0.008” of runout in the receiver threads. I rotated the receiver 90 degrees and ran my indicator over the threads to get a reading, rotated another 90 degrees, etc…

I haven’t checked the bolt lugs yet. I need to...
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Thread 'First Remington 700 build. Do nothing at all, true the face or full blueprint?'

I've got a new, unused Remington 700 action with a pre-installed threaded 20" 308 barrel, and a new factory bolt from PTG. Both items are from the bankruptcy sale. I checked the headspace and it's right at 1.630". The bolt handle seems to be in the right place for good primary extraction. There's maybe a 0.005" gap between the front of the bolt handle and the handle cutout when it's fully closed.

J45FOGm.jpeg


mFaLpkk.jpeg


This will eventually be a M40 clone and I have a barrel on the way from Bartlein in July. In the meantime, I'd like...
 
tonyben said:
Good morning! I'm moving forward with my Vietnam era M40 project and I'm getting ready to cut the barrel. Can you check my numbers?

I gauged my receiver and bolt dimensions yesterday. I created an Excel spreadsheet to calculate the barrel tenon specs and the bolt nose cutout specs as well as headspace gauge protrusion specs.
XZHCJrT.png


Tony.
Click to expand...
I would double check dimension J, bolt nose depth into the breech
seems every Rem bolt nose is different
Last few I did I remember cutting .170" deep into the tenon of the barrel
----Measure off front of the bolt nose to front of lugs, you want a little clearance .005" min... .015" is ok
---
After that, if when you close the bolt and feel resistance, then you know the Tenon
Dimension H needs to be shaved a little bit because the front of the lugs are touching the back of the barrel.
Dimension (I) looks good, I dont think I've ever went above .710"
---
it sucks when you don't know if it is the bolt nose hitting the barrel, or the lugs hitting the breech
if you for sure clearance enough for the bolt nose, it is then easy to determine it can only be one other thing, hitting causing resistance of bolt closure.
 
ELR LVR said:
I would double check dimension J, bolt nose depth into the breech
seems every Rem bolt nose is different
Last few I did I remember cutting .170" deep into the tenon of the barrel
----Measure off front of the bolt nose to front of lugs, you want a little clearance .005" min... .015" is ok
---
After that, if when you close the bolt and feel resistance, then you know the Tenon
Dimension H needs to be shaved a little bit because the front of the lugs are touching the back of the barrel.
Dimension (I) looks good, I dont think I've ever went above .710"
---
it sucks when you don't know if it is the bolt nose hitting the barrel, or the lugs hitting the breech
if you for sure clearance enough for the bolt nose, it is then easy to determine it can only be one other thing, hitting causing resistance of bolt closure.
Click to expand...
If you look at my chart, dimension B1 and B2 are the two bolt lug faces and their distance to the end of the bolt nose. The smallest value is the lug that's farthest forward (it's closer to the bolt nose). I set dimension J to equal the the smaller value of B1 or B2. Since I set my tenon length to give me 0.010" of clearance from the front of the closest bolt lug, then my bolt nose clearance should be 0.010" as well.

I can reduce dimension I if you think it's excessive.

I plan on headspacing the barrel using headspace gauge protrusion. I'll then place my bolt on the gauge and I should see clearance between the bolt lugs and the tenon. The next check will be hand tightening the receiver to the barrel and checking headspace. It should be a thou or two over HS. This should close when I torque the barrel on.

Tony.
 
Taylorbok said:
I'm trying to learn but I can't make sense of it.
HS on the brass doesn't affect the tenon length

Unless he's referring to HS as the distance from the lugs to the action face + recoil lug.
Click to expand...
I couldn't make sense of it either. I think he's saying to leave the case-head 0.010" past the tenon. So find your headspace location and set the tenon 0.010" short (or forward) of that measurement so you have the headspace gauge sticking out past the tenon.

Tony.
 
tonyben said:
I can reduce dimension I if you think it's excessive.


Tony.
Click to expand...
Try it out, it's not hard to fix if something hits upon bolt closure
many times everything works right until we Torque that barrel down
then (F^$#U) I gotta dial in the barrel again!!! just to skim .005" off somewhere
(Blue sharpie helps locate rubs )
----
Anyway, upon looking at
Dim H minus F = .708"
Then Comparing that to Dim G of .715"
----
I am only seeing a clearance of .007"
and we all torque our barrels to different specs so ya know, that right there feeds into it.
It is early and maybe I'm not fully awake yet but, I'm not seeing your .010" clearance my friend.?
---
In this setup the only dimension I like close tolerance is the Dim (I) on the Tenon---
---(To help keep the bolt nose aligned with the bore when closed)
But if you think about it The bolt nose does not have to be close to anything at all foreward of itself
and the front face of the lugs do not have to touch anything at all, which is why I ensure a good amount of tolerance between those upon machining so when I do torque the barrel down, knowing it can suck up a good .003" (The recoil lug may compress .001" also )
That I have machined in enough wiggle room I dont need to go back and have to
Cut the chamber deeper, cut the tenon, etc.
Not telling you how to do it, just sharing my experience in what has happened to me and how I personally prevent it.
---
As a side note - ya ever get powder in your chamber when extracting a live round?
 
Last edited:
Making the tenon 0.010" shorter than the HS does several things. One- the HS gage protrudes from the tenon allowing one measurement with a depth mic to measure HS. Second- It makes machining the counterbore much easier. As I said , touch, set travel indicator, using the number for the bolt fact to the nose, cut the CB. I open the diameter up some and take one measurement in the whole operation of machining the CB.

Edit; it's easy to check end play. Screw the action on, insert bolt and move the bolt back and forth. 5 thou just barley moves, 10 thou it will click
 
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