Gunsmithing Receiver Truing process

wnroscoe

wnroscoe

Gunny Sergeant
Full Member
Minuteman
Jun 12, 2006
3,907
56
NW Louisiana
#1
I thought I'd share this with those that may be interested. I just finished it up today. Sorry, it's kinda long but, theres pictures
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Here is a Remington 700 Receiver and the truing process I use. This rifle project will end up being a 300RUM and be used as a Whitetail Rifle. Poor little deer. The first two pics show how the receiver looks as it comes off the barrel. That gunk is some sort of thread lock Remington uses.

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The next pics show the receiver, a truing collar I made, bolt raceway bushings and a hardened, ground .500” indicating bar. Also, there are pics showing the receiver installed in the truing collar to give you an idea as to how it’s held. This bar was manufactured for me by Dave Kiff at PTG and is ground, heat treated, stress relieved and ground once more to the final diameter. Now, here’s the first deal. When a receiver is indicated in the lathe we have to use the bolt raceway as the standard. Some smiths will use a tight fitting ground piece of bar stock or small pump shaft to indicate off of. This particular receiver was very straight to start with but, the ID of the front receiver ring was .7015” and the ID of the rear receiver ring was .702”. I’ve seen some receivers that measured .701” in the front ring and .705” at the rear ring. How is a piece of bar stock or small pump shaft going to lock up the same in the bolt raceway if the receiver ring ID’s are not the same. The trick or key in my opinion is to use tight fitting bushings in the raceway with an ID of .500” and use a .500” ground rod to indicate off of. This rod must also be hardened and stress relieved, if not, in time it will start to move around and loose its straightness. This first step will dictate the quality of the truing job. It’s imperative that this first step of the process be taken seriously and indicated as close to zero as possible. The machining that follows will dictate whether or not that the receiver threads are concentric and the lug abutment faces and receiver face are perpendicular to the bolt race way. This is very crucial to accuracy.

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The next pics show me indicating the truing collar in and the receiver after it was indicated in to .00005”. That’s right, .00005” not .0005”. Since the collar was made to close tolerances, I have to indicate it in just to get the receiver indicated after it’s installed in the collar. Dial in took less than 10 minutes.

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The next pics show the receiver face with a very light (.0005”) facing cut to it. Using either Die Chem. Blue or a Blue Sharpie pen you can see the low spots left after machining. Here, on the receiver face, you can see the low spots left blue and high spots cleaned up. It only took a facing cut of .0015” to get the clean up cut you see. Look close at the first pictures and you may be able to make out the saw marks on the receiver face prior to the facing cuts being made.

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The next pic shows a small boring bar I use to remove taper if any, the crest of the receiver threads and to make a clean up facing cut to the lug abutments. There is a before and after pic showing the cuts made, very light cuts are used. Prior to cutting, I touch off on the lug abutments with the boring bar with the lathe turned off. I set a travel dial to zero after I establish the correct depth and feed by hand very slow until I reach that zero. I then make a facing cut on the lug abutments with a very slow feed.

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The next pics show the threading tool and threads after clean up and a completely trued Remington 700 receiver. In previous pictures you may be able to make out the chatter marks in the threads from the factory threading process. The threads are now smooth and chatter free. I’m starting to cut a small relieve groove in the receiver threads at the front of the receiver, this helps me measure the major thread diameter in the receiver and helps me establish an OD for the barrel tennon prior to threading. The threads in this receiver cleaned up with a major diameter of 1.0735”.

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Bolt Truing

First, I remove the ejector and firing pin assembly from the bolt body and screw a fixture into the rear of the bolt to hold it in the lathe. I then place a small cat head that I made on the bolt face and line it up in the dead center with grease in the center hole to keep the cat head from galling to the dead center. I also check the center of my tooling to the part after it's indicated in. This is crucial to a good finish on the part being machined. The tooling is adjusted until the machinist scale is leaning out on the top half, this lets you know the tooling is just a tad below center. Perfect.

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Next, I set up to make truing cuts to the rear of the bolt lugs. I do so by placing the cutting tip of the tooling against the part to be cut and use a travel dial set to zero. The travel dial is stuck to the bed ways and reads against the carriage. This lets me just touch the part without taking too much material off. You just want a clean up pass.

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Next, I set up to make truing cuts to the front of the bolt lugs, bolt nose and bolt face. The part I hate the most about the entire process is having to use a steady rest but, I guess it's a necessary evil. I adjust the steady rest rollers to just touch the bolt body while it is being held in the first set up. You just wan t enough contact between the rollers and the bolt body so movement is eliminated during the truing process. Again, the travel dial is used so no more metal than needed is removed.

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I then change tooling to cut the bolt face. The tooling is a piece of Rex95 Tool Steel I ground to make these cuts. Very light cuts are made, you just want a clean up pass. It's so tight when making this cut, I couldn’t get my camera into position for a picture.

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After truing cuts were made to bolt face
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This is the completed bolt after truing. I feel so strongly about the benefits of truing a receiver and bolt, I wont even barrel a rifle with out it unless I do it or it's already been performed by someone else.

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#3
Re: Receiver Truing process

thanks for sharing your techniques. they are very similar to what i am doing. i asked the girls that answer the phone at ptg several times if i could get an indicator rod like that made and they kept telling me they couldn't. i guess i will need to talk to dave himself. i ended up using a 1/2" drill rod that didn't even bump a .0001" indicator so it's very true. did you make the bushings or buy them from ptg?
 
#4
Re: Receiver Truing process

I've only made one set of bushings. They were the 705" OD, .500" ID bushings and made from brass. I'll purchase from now on. The rod was one of those special run items. I think Dave has also made them for Greg Tannel. You can purchase a .500" diameter pump shaft from McMaster Carr. Just make sure it's heat treated.

All my pictures didnt come out but, at least the links work. Dont know whats up with that.
 
#14
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shooter65</div><div class="ubbcode-body">Very nice write up. Thank you for your time and effort.

How much would you say the average 700 action is off? </div></div>

I will be the first to say there is no way to know until you have it apart. Some are better than others but if you have a factory gun shooting 1/2 moa there probably isn't much having a truing job will get you. I normally don't have any action work done until a rebarrel or if I buy one secondhand I'll pull the barrel and check everything out
 
#15
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shooter65</div><div class="ubbcode-body">Very nice write up. Thank you for your time and effort.

<span style="font-weight: bold">How much would you say the average 700 action is off? </span></div></div>

It took a facing cut of .0015" to clean up this receiver face. The rest of the receiver and bolt was very straight compared to others I've seen. The problem is this, the face may only be off by .001" or so, the factory recoil lug by as much as .002", one of the receiver lugs may be out by as much as .002" to .005" and so on. What you end up with is stacked tolerances that all add up to several thousandths, very bad for accuracy. You've all read the post about guys that can’t get their rifle to zero at 100 yards with the Mil Spec Rails, stacked tolerances have the barrel looking off too much. The benefit of this entire process is the removal of variables and shot to shot consistency with the addition of match grade components and quality workmanship. If your 700P is shooting .5moa or better, it's a safe bet that it was pretty straight right out of the box. It’s hard to say how much any factory receiver will be off but, one things for certain, they all are to a degree.
 
#17
Re: Receiver Truing process

By truing up a 700 action how much accuracy would a rifle gain?
10% 20%???




<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shooter65</div><div class="ubbcode-body">Very nice write up. Thank you for your time and effort.

<span style="font-weight: bold">How much would you say the average 700 action is off? </span></div></div>

It took a facing cut of .0015" to clean up this receiver face. The rest of the receiver and bolt was very straight compared to others I've seen. The problem is this, the face may only be off by .001" or so, the factory recoil lug by as much as .002", one of the receiver lugs may be out by as much as .002" to .005" and so on. What you end up with is stacked tolerances that all add up to several thousandths, very bad for accuracy. You've all read the post about guys that can’t get their rifle to zero at 100 yards with the Mil Spec Rails, stacked tolerances have the barrel looking off too much. The benefit of this entire process is the removal of variables and shot to shot consistency with the addition of match grade components and quality workmanship. If your 700P is shooting .5moa or better, it's a safe bet that it was pretty straight right out of the box. It’s hard to say how much any factory receiver will be off but, one things for certain, they all are to a degree. </div></div>
 
#18
Re: Receiver Truing process

shooter65 said:
By truing up a 700 action how much accuracy would a rifle gain?
10% 20%???

No one can tell you that for certain. You might gain some and you might gain nothing. Too many other variables to consider. I have seen known out of true actions with very good barrel that were chambered correctly shoot better then the operator could ask for. I have seen factory out of the box rifles shoot better then the operator could ask for. I have also seen properly trued actions with a good barrel properly chambered shoot like crap. There are just too many variables to give a proper answer.

I will say I have seen and done some crazy machining to factory action just to see how it would affect the accuracy to a properly chambered barrel and you would be surprised at just what you can get away with.
Click to expand...
 
#19
Re: Receiver Truing process

This would explain an experience of mine in which a factory PSS, with a barrel that clearly deviated from the action's centerline, would shoot 1/2 moa all day long. Aesthetically this bothered me, so I had this rifle blueprinted and rebarreled. The machinist told me that the CL of the bore was different from the CL of the barrel!

After the effort and expenditure it shot... 1/2 moa.

Perplexing is an understatement.

But at least the rifle looks as good as it shoots.


Respectfully,
Bill
 
#20
Re: Receiver Truing process

So what you are saying it a good barrel and chamber is where it is at?




<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: HateCA</div><div class="ubbcode-body">
shooter65 said:
By truing up a 700 action how much accuracy would a rifle gain?
10% 20%???

No one can tell you that for certain. You might gain some and you might gain nothing. Too many other variables to consider. I have seen known out of true actions with very good barrel that were chambered correctly shoot better then the operator could ask for. I have seen factory out of the box rifles shoot better then the operator could ask for. I have also seen properly trued actions with a good barrel properly chambered shoot like crap. There are just too many variables to give a proper answer.

I will say I have seen and done some crazy machining to factory action just to see how it would affect the accuracy to a properly chambered barrel and you would be surprised at just what you can get away with.





</div></div>
Click to expand...
 
#21
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 051F</div><div class="ubbcode-body">im glad youre the man i picked for my job! my big box of parts should be showing up any day now. </div></div>

Showed up yesterday. Is that a barrel from Boots O.?
 
#22
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shooter65</div><div class="ubbcode-body">By truing up a 700 action how much accuracy would a rifle gain? 10% 20%???</div></div>

Randy's spot on with his statements. It really boils down to shooter and ammo as to how much accuracy can be expected / gained. In an ideal world, the center line of the firing pin, bolt, receiver, chamber, bore, barell, muzzle and crown will be same/same. If the center line of these things are the same/same and you have tuned ammo and a good shooter, .250 moa is a very real possibility.
 
#24
Re: Receiver Truing process

Good write up William! BTW, the rifle you cleaned the chamber on and squared the reciever face up, is shooting 4.5" groups at 600yds for me.thanks again.
 
#25
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 81sfo</div><div class="ubbcode-body">Good write up William! BTW, the rifle you cleaned the chamber on and squared the reciever face up, is shooting 4.5" groups at 600yds for me.thanks again. </div></div>

I'm glad it worked out for you Jose. Good shooting.
 
#26
Re: Receiver Truing process

I have a question

Building a 338Lapua on a 700 LA.....

The bolt face must be opened up to the point where there's almost no "ring" around the face.(sorry I don't know the proper term for that ring)
With Lapua's on a 700, you must use a "Sako" or "M16" style extractor anyways, so you can do away with the clip in ones...


My question is, what if you turned that ring away completely?
Have just an open, true face with an extractor and ejector(s)
What then?
The extractor would be protruding to the point it could get damaged right? But without setting the barrel back, it wouldn't hit the anything.

Feel free to PM me the answer. I check my PMs more than I read these threads. I might forget to check.

Thanks in advanced
 
#29
Re: Receiver Truing process

Since not all receiver IDs(bolt way) are the same, how do you fit the bushings so perfectly inside the receiver? They fit very snug right? Or is there a way to adjust them? Do you just have different sizes?
Then that .500" bar... You obviously buy those right? or do you turn them yourself from tool steel? Seems it would have to be straight as hell.


EDITED: I guess I didn't read everything above


Oh and my question about the face ring was answered pretty much. I still think something could be done to re-design the bolt to do-away with this, but that's for another day.


Thanks guys
 
#30
Re: Receiver Truing process

Great thread!

Do you go through generally the same indicating process when setting up a barrel to be threaded, chambered and crowned?

Also, what if the bolt diameter is significantly smaller than the raceway, would not that effect how it interfaces with the chamber once the pressure of the cocking spring pushes it upward in the rear of the bolt or is that one of those things that really does not matter?
 
#31
Re: Receiver Truing process

I'd purchase the Surgeon XL for a 338L build. The 300RUM and Edge is really more than the Remington 700 wants. If you have to remove metal from the bolt nose to make it work, I'd be a little leery of it.
 
#32
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AZPrecision</div><div class="ubbcode-body">Since not all receiver IDs(bolt way) are the same, how do you fit the bushings so perfectly inside the receiver? They fit very snug right? Or is there a way to adjust them? Do you just have different sizes?
Then that .500" bar... You obviously buy those right? or do you turn them yourself from tool steel? Seems it would have to be straight as hell.
</div></div>

I use multiple size bushings and try them until I get the fit I want.

Yes, they fit too tight for anything else.

I purchase all of my tooling from Dave Kiff at PTG, even the .500" Bar
 
#36
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mdesign</div><div class="ubbcode-body">Great thread!

Do you go through generally the same indicating process when setting up a barrel to be threaded, chambered and crowned?

Also, what if the bolt diameter is significantly smaller than the raceway, would not that effect how it interfaces with the chamber once the pressure of the cocking spring pushes it upward in the rear of the bolt or is that one of those things that really does not matter? </div></div>

Yes, I double indicate the barrel as well, breech for chambering, muzzle for crowning.

Pressure at the cocking piece and trigger sear bar is an issue if the bolt raceway and bolt body are of different diameters. The more of a difference, the more deflection you have. For some, sleeving the bolt is the only logical choice.
 
#37
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Just Shoot</div><div class="ubbcode-body">Very nice work. Now when for the lesson on chambering??? </div></div>

Just added a short version for you. New topic.
 
#38
Re: Receiver Truing process

William, what do you do when your barreling a custom action such as a stiller, surgeon or lawton? Do you still run it through the same procedures or do check everything first and let it stand if its within your standards?
 
#39
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Norcal Phoenix</div><div class="ubbcode-body">William, what do you do when your barreling a custom action such as a stiller, surgeon or lawton? Do you still run it through the same procedures or do check everything first and let it stand if its within your standards? </div></div>

I've yet to find the need to machine a custom receiver. So far they've all GTG. These include the Surgeon RSR, Stolle Panda and Grizzly, Stiller SS Viper & Predator, Bat Machine and Phoenix Machine. If a custom receiver was out by any amount, I’d simply return it.
 
#40
Re: Receiver Truing process

Great write up William. Thanks for taking the time and sharing.

I was wondering (and maybe Randy could throw in a comment here too), how often if ever, do you remove enough from the bolt lugs and reciever lug abutments that you need to remount the bolt handle forward? When you add in the bolt face cut, how often do you see problems due to to little extractor cam?

With the minimal removal shown here I'd imagine it's rare to never. I know Randy has commented that just truing the reciever face will give great accuracy improvement and that appeared to be the most aggressive cut.

Thanks agian, DC
 
#42
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dinc</div><div class="ubbcode-body">Great write up William. Thanks for taking the time and sharing.

I was wondering (and maybe Randy could throw in a comment here too), how often if ever, do you remove enough from the bolt lugs and reciever lug abutments that you need to remount the bolt handle forward? When you add in the bolt face cut, how often do you see problems due to to little extractor cam?

With the minimal removal shown here I'd imagine it's rare to never. I know Randy has commented that just truing the reciever face will give great accuracy improvement and that appeared to be the most aggressive cut.

Thanks agian, DC </div></div>

DC,

The truing cuts are minimal at best. If re-timing the handle/bolt is needed after the truing process is completed, chances are it was needed prior to starting. I've removed one handle so far though and re-timed it.
 
#44
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: g5</div><div class="ubbcode-body">Do you ever weld them? </div></div>

The one I removed, I tiged it back on.
 
#46
Re: Receiver Truing process

Just looked at this again. I love your action trueing fixture. It makes me want to remake mine to copy yours. Also your bolt spider....since imitation is the sincerest form of flattery...do you mind if I copy that too?
I like the way you have taken some great ideas and improved upon them. Now if you will just figure out a way to true bolt faces and lugs in a single set up without having to drag out the steady rest you will be my hero.
 
#47
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: eddybo</div><div class="ubbcode-body">Just looked at this again. I love your action trueing fixture. It makes me want to remake mine to copy yours. Also your bolt spider....since imitation is the sincerest form of flattery...do you mind if I copy that too? </div></div>

Go ahead, I dont mind.
 
#48
Re: Receiver Truing process

Would there be too much tool deflection to machine the bolt with a similiar fixture you used on the action. I would think that it would be possible to indicate it pretty easliy just leaving enough hanging out to machine the backside with maybe a small groover or somthing. Also what did you use to strip the action.
 
#49
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 6.81star</div><div class="ubbcode-body">Would there be too much tool deflection to machine the bolt with a similiar fixture you used on the action. I would think that it would be possible to indicate it pretty easliy just leaving enough hanging out to machine the backside with maybe a small groover or somthing. Also what did you use to strip the action. </div></div>

You'd have to have a spindal bore large enough for the bolt handle to stick into. In order to get the bolt body running true, this is how most are indicated. Good idea though.
 
#50
Re: Receiver Truing process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 6.81star</div><div class="ubbcode-body">Would there be too much tool deflection to machine the bolt with a similiar fixture you used on the action. I would think that it would be possible to indicate it pretty easliy just leaving enough hanging out to machine the backside with maybe a small groover or somthing. Also what did you use to strip the action. </div></div>

You'd have to have a spindal bore large enough for the bolt handle to stick into. In order to get the bolt body running true, this is how most are indicated. Good idea though. </div></div>

when you guys were discussing this the other day, an idea popped into my head. so i don't hijack your thread with all my pictures, here is a link to my solution: link
 
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