Remington 700 replacement bolt.

[Rem700 shooter]

So I’m still pretty new to gun smithing but have been a machinist 20 something years. I have cut several chambers and also trued up several actions and they’ve all shot great. I have a customer that bought an aftermarket bolt for a rem 700 chambered in .300 PRC the rifle was previously trued by another smith. New bolt won’t even go in battery until I torqued barrel off. Just taking some quick measurements off of old bolt and new bolt with dial calipers, it looks like I will need .01-.015”. I also confirmed radial clearance in the counterbore. I haven’t sat down and took all measurements with a depth Mic as I have other projects I need to finish first before I dive all the way into this one, but I’m trying to get a plan together for when I get to it.

I would really like to take off the .010” off the back off the bolt lugs but it has a hard nitride finish and it’s a nice and sorta pricey bolt so this probably isn’t an option, which leads me to my ultimate question, could I take that out of the lug abutments? Is there a minimum thickness they should be? I usually only take a few .001 when I blue print, and I assume at least that has been taken already. I would much prefer this than setting up barrel, re dialing chamber, and buying a reamer.

 

[Fast14riot]

The barrel is a consumable, best to fit it to the action and bolt. Doesn't sound like it would headspace anyway.

 

[ricco1949]

Do.not cut lug abutments other than to true them. You will lose primary extraction.

 

[Wesson]

Mess with the barrel only.
Don't touch the action/bolt.

 

[LVLAaron]

Fix the barrel.

 

[jackieschmidt]

YES….to #3 #4 5#.

 

[paperpuncher]

Stick the bolt in the action without the barrel in place. Examine the components and how the work together I would start by looking at the clearances between the bolt handle and the slot.Make the determination on how to proceed from there. Altering the bolt or the actions is going to affect timing and extraction evaluate the changes you want to make before you trim the bolt or action

 

[DaveTooley]

As others have said alter the barrel. Layout the costs to your customer. Then it's his decision how to proceed. Two rules in my shop. #1 Don't do anything to make the phone ring. #2 It's OK to say NO

 

[Rem700 shooter]

Alright! Thanks guys, I sorta guessed this was gonna be the way but hoped for a short cut. I’ll get the new bolt In measure and adjust counterbore/chamber depths accordingly. Customer will be fine with whatever it costs, which will be the better part of a chambering job.

 

[LVLAaron]

Alright! Thanks guys, I sorta guessed this was gonna be the way but hoped for a short cut. I’ll get the new bolt In measure and adjust counterbore/chamber depths accordingly. Customer will be fine with whatever it costs, which will be the better part of a chambering job.

For what it's worth, if you cut the lugs, you increase headspace. Figure out what part of the barrel is making contact, give it a quick trim, and be done

 

[Rem700 shooter]

For what it's worth, if you cut the lugs, you increase headspace. Figure out what part of the barrel is making contact, give it a quick trim, and be done

Right, I’m assuming that chamber and counterbore needs to be set back about .01-.015 . The old bolt had about .011” of clearance, this new Mack brothers bolt will just start to rotate and then get tight. New bolt has same bolt nose to bolt face depth, but from the back of lugs to bolt nose it’s .01ish longer(I just put some dial calipers on it). I’m guessing it probably would have been a drop in or very close but the .01 is what got took off when original bolt was trued then re barreled. That’s what I was hoping to accomplish by trimming lug abutments or bolt lugs. They’re right above though. It needs to come out of the barrel.

In the unlikely scenario that i get bolt clearance where it needs to be and im only a few .001 from making headspace and it looks like i have ample primary extraction I still may take it from lug abutments to keep from buying a reamer, I just didn’t want to take .01” from them.

 

[kendog]

You're kinda headed the long way around the barn with this. Measure the bolt and receiver like you were to fit a barrel and cut the barrel to it. That is the short cut.

 

[ELR LVR]

So I’m still pretty new to gun smithing but have been a machinist 20 something years. I have cut several chambers and also trued up several actions and they’ve all shot great. I have a customer that bought an aftermarket bolt for a rem 700 chambered in .300 PRC the rifle was previously trued by another smith. New bolt won’t even go in battery until I torqued barrel off. Just taking some quick measurements off of old bolt and new bolt with dial calipers, it looks like I will need .01-.015”. I also confirmed radial clearance in the counterbore. I haven’t sat down and took all measurements with a depth Mic as I have other projects I need to finish first before I dive all the way into this one, but I’m trying to get a plan together for when I get to it.

I would really like to take off the .010” off the back off the bolt lugs but it has a hard nitride finish and it’s a nice and sorta pricey bolt so this probably isn’t an option, which leads me to my ultimate question, could I take that out of the lug abutments? Is there a minimum thickness they should be? I usually only take a few .001 when I blue print, and I assume at least that has been taken already. I would much prefer this than setting up barrel, re dialing chamber, and buying a reamer.

1. Sounds more like you need to cut some off the back of the tenon
2. Counterbore deeper same amount
(the front of the lugs may be hitting/touching the back of the barrel tenon
Which in effect is pinching the lugs between the barrel and the lug ramps)
So you need clearance
Do these 2 things
Done
No need to mess with the bolt,
as Fast14riot said, the barrel is the consumeable.... not the bolt.
so cut on the barrel instead
Since the barrel is most likely what's stopping the bolt from closing
You will know this for sure if you unscrew the barrel about 1/4" to provide clearance and the bolt suddenly closes all the way.
---------------
With the barrel loosely threaded into the action
1. Close the bolt
2. then start screwing the barrel in until it stops against the bolt
3. Use feeler gauges to measure between barrel and recoil lug or between action and recoil lug
add approx .003" to this measurement to account for torquing down
Make your cuts
Then Torque Barrel to action and see if bolt closes
if so you have .003" or less headspace
If not, cut .001" more at a time until the bolt closes smoothly
Done
-------------
As the above poster said, this method IS............the shortcut
the longest part of this operation is dialing in the barrel perfectly concentric so your conterbore cut is also concentric with the bore and the bolt nose.
10 Mins. tops to dial in

 

[Rem700 shooter]

1. Sounds more like you need to cut some off the back of the tenon
2. Counterbore deeper same amount
(the front of the lugs may be hitting/touching the back of the barrel tenon
Which in effect is pinching the lugs between the barrel and the lug ramps)
So you need clearance
Do these 2 things
Done
No need to mess with the bolt,
as Fast14riot said, the barrel is the consumeable.... not the bolt.
so cut on the barrel instead
Since the barrel is most likely what's stopping the bolt from closing
You will know this for sure if you unscrew the barrel about 1/4" to provide clearance and the bolt suddenly closes all the way.
---------------
With the barrel loosely threaded into the action
1. Close the bolt
2. then start screwing the barrel in until it stops against the bolt
3. Use feeler gauges to measure between barrel and recoil lug or between action and recoil lug
add approx .003" to this measurement to account for torquing down
Make your cuts
Then Torque Barrel to action and see if bolt closes
if so you have .003" or less headspace
If not, cut .001" more at a time until the bolt closes smoothly
Done
-------------
As the above poster said, this method IS............the shortcut
the longest part of this operation is dialing in the barrel perfectly concentric so your conterbore cut is also concentric with the bore and the bolt nose.
10 Mins. tops to dial in

Yep got it, this is the plan. All I was saying in a world were there weren’t other considerations, it would be easier/quicker to throw bolt in truing fixture, whack the .01” off the back of the lugs, or fixture the reciever and get it out of abutments, rather than face tenon, deepen counterbore, deepen chamber. Not the either are highly complicated machining operations, the first two would be quicker. Thank you all for the help, im sure I’ll be back for more.

 

[AlNyhus]

The early Mack Bros actions wouldn't accept 700 'prefit' barrels unless .010-.015 was faced off the barrel. Later on, they changed that. I know you're working with their 700 replacement bolt... but it's interesting that you run into the same numbers. -Al

 

[2dogs]

Hmmm, you might consider pulling the barrel, set the headspace without the lug in place, measure the gap, and cut a new lug to that dimension. Just a thought…

 

[ELR LVR]

Hmmm, you might consider pulling the barrel, set the headspace without the lug in place, measure the gap, and cut a new lug to that dimension. Just a thought…

Well Shizzle!
That is not a bad idea!!!
A guy could just 4 jaw the lug then face it to desired thickness slightly over barrel dia.
I like this idea!!!
Hardest part would just be getting the lug perfectly squared up
but with a .0001" indicator and the proper tapper hammer
Should be no biggee

 

[ELR LVR]

Yep got it, this is the plan. All I was saying in a world were there weren’t other considerations, it would be easier/quicker to throw bolt in truing fixture, whack the .01” off the back of the lugs, or fixture the reciever and get it out of abutments, rather than face tenon, deepen counterbore, deepen chamber. Not the either are highly complicated machining operations, the first two would be quicker. Thank you all for the help, im sure I’ll be back for more.

Read above 2 posts
---------------------------
Also you could do a little of both of what you said depending on how far it is out
And hopefully not cutting the back of the lugs any more than .005"

 

[Rem700 shooter]

Read above 2 posts
---------------------------
Also you could do a little of both of what you said depending on how far it is out
And hopefully not cutting the back of the lugs any more than .005"

Yeah I’ve thought about doing this before correcting head space either way. You could just mill most of it then grind parallel. Only problem is your barrel engraving wouldn’t be timed up unless head space was out exactly a whole thread. I would be fine with this on some of the rifles I own but wouldn’t be comfortable doing this for a paying customer, also this rifle has a .360” recoil lug. I dunno of one any thicker. It is clever idea though.

 

[JMA]

Do the Mack Bros replacement bolts nee to be fitted to action for proper primary extraction?
Distance from locking lug to handle