Action Mandrels

[Speedy7722]

I recently got a new-to-me lathe and am ready to start hobby truing actions and chambering barrels. I have already acquired some tooling for chambering (JGS reamer holder, Interapid long stylus, etc) and am looking to get setup to check and potentially true up some of my current actions.

I have spent many hours browsing past threads and see that full diameter action mandrels are considered by several to be the ideal option for checking alignment of the critical surfaces relative to the raceway. I would rather spend the money now on the better solution if possible as I have no tooling for this.

With that said, I saw there was a group buy some years ago for custom ground mandrels. Online I can only find those that PTG has in 0.001 increments from .699 to .705 on backorder and the Labounty mandrels in .701 and .703. Can anyone speak to the quality of PTG mandrels or recommend any alternative options? If the PTG are sufficient quality, could 1 thou increments be fine enough or would I need really need those 1/2 thou sizes that others had custom ground? Has anyone used the La Bounty mandrels?

If no good full diameter options exist, I suppose I will look into getting a set of bushings and a .500 rod.

 

[jackieschmidt]

I just make my own.
I use 1175 steel. The key to insuring it being dead straight is to turn it between centers, insuring that you are not inducing any deflection in the finished piece.

 

[Speedy7722]

I just make my own.
I use 1175 steel. The key to insuring it being dead straight is to turn it between centers, insuring that you are not inducing any deflection in the finished piece.

I will make my own if decent commercial options aren't available. Did you mean 1075 steel? I'm not finding anything online about 1175.

 

[Walt Krafft]

Make your own. Stop wasting time looking for store bought ones.

 

[jackieschmidt]

I will make my own if decent commercial options aren't available. Did you mean 1075 steel? I'm not finding anything online about 1175.

Sorry. I meant 1144, also called going by the name Stressproof.

 

[Will Henry]

If you are working on a Remington action and it is crooked (which it must be if you need to true it), then there is a fair chance that a straight, close fitting mandrel will either have to bend a little or the action will have to deflect a little to accommodate the mandrel. on top of that, the action is likely to be a little different in diameter from the bridge to the receiver ring. For this reason, I make my mandrels so that they contact at the front and the rear and so the rear contact is semi-spherical. The mandrel then establishes the centerline of the receiver and this is the line to which everything is oriented. The threads are made to be concentric and co-axial to this line. The locking lug seats are cut perpendicular to it. When the bolt is trued and fitted to the receiver, it ends up so that the established centerline of the bolt is co-axial with the established centerline of the receiver. WH

 

[tobnpr]

I use Manson's tapered bushing system for M700s...

Action Indicating | Manson Precision Reamers

Category: <span>Action Indicating</span>

mansonreamers.com

 

[Speedy7722]

If you are working on a Remington action and it is crooked (which it must be if you need to true it), then there is a fair chance that a straight, close fitting mandrel will either have to bend a little or the action will have to deflect a little to accommodate the mandrel. on top of that, the action is likely to be a little different in diameter from the bridge to the receiver ring. For this reason, I make my mandrels so that they contact at the front and the rear and so the rear contact is semi-spherical. The mandrel then establishes the centerline of the receiver and this is the line to which everything is oriented. The threads are made to be concentric and co-axial to this line. The locking lug seats are cut perpendicular to it. When the bolt is trued and fitted to the receiver, it ends up so that the established centerline of the bolt is co-axial with the established centerline of the receiver. WH

I will attempt to make some of my own. I have a 700 action from the 1970s, a newer winchester, and other 700 clones I would atleast like to check.

I am trying to visualize the how the semi spherical rear contact helps with the alignment. Is it allowing some room for the both contacts to fit (tightly) in the non perfect bore?

 

[Sniperhandle]

I will attempt to make some of my own. I have a 700 action from the 1970s, a newer winchester, and other 700 clones I would atleast like to check.

I am trying to visualize the how the semi spherical rear contact helps with the alignment. Is it allowing some room for the both contacts to fit (tightly) in the non perfect bore?

These are 25.00 each and are precision ground, Sometimes making something yourself makes sense, But not when these are that economical. I have and use these, They work well.
I have made mandrels, It takes quite a bit of time. Here are some I have made, I have made probably 15 or so of them, One for most milsurps and most older actions.

Although I don't true like that anymore since I use a tru-bore and a six jaw.

LA BOUNTY RECEIVER MANDRELS

Check out LA BOUNTY RECEIVER MANDRELS available Online at Brownells Today and many more Rifle Tools products are available in our Tools & Cleaning Department. Write a review.

www.brownells.com

 

[WSnyder]

These are 25.00 each and are precision ground, Sometimes making something yourself makes sense, But not when these are that economical. I have and use these, They work well.

LA BOUNTY RECEIVER MANDRELS

Check out LA BOUNTY RECEIVER MANDRELS available Online at Brownells Today and many more Rifle Tools products are available in our Tools & Cleaning Department. Write a review.

www.brownells.com

Those are great (I have a set) but they won’t cover every action you will encounter.

I’d be looking for .701-703 in .0005 increments.

Buy some extra LaBounty .703” and find someone to grind them to size.

 

[Fast14riot]

I will attempt to make some of my own. I have a 700 action from the 1970s, a newer winchester, and other 700 clones I would atleast like to check.

I am trying to visualize the how the semi spherical rear contact helps with the alignment. Is it allowing some room for the both contacts to fit (tightly) in the non perfect bore?

A spherical rear allows the front to point in any direction while maintaining concentric alignment for banana shaped receivers.

 

[Will Henry]

A spherical rear allows the front to point in any direction while maintaining concentric alignment for banana shaped receivers.

Exactly so. I started doing this when I had one 700 which was decidedly banana-like. WH

 

[Judd]

Alan Warner did a group buy for us a few years back. I was lucky to get a set from that, they are awesome but there wasn’t anything cheap about them. That’s not a complaint, precision isn’t cheap and these things are precise!

 

[Sniperhandle]

Alan Warner did a group buy for us a few years back. I was lucky to get a set from that, they are awesome but there wasn’t anything cheap about them. That’s not a complaint, precision isn’t cheap and these things are precise!

I think Alex Wheeler had a group buy of mandrels too, Or maybe he had a bunch made and sold them.

 

[Jud96]

I recently talked to an industry manufacturer of precision tools (not PTG) and they mentioned offering solid ground mandrels in .0005 increments. Having the mandrel dead nuts straight, round, and concentric is very important or you’re inducing error into the readings. If the runout is out just .0001 at the face, that equals .0007-.0009 at the tang. So if you don’t have a highly precision mandrel, then it’s not going to guarantee the action is dialed in as good as possible. Just my thoughts. I’ve used some custom ground mandrels when I worked at Pierce and will never use a rod with bushings again.

 

[Sniperhandle]

I recently talked to an industry manufacturer of precision tools (not PTG) and they mentioned offering solid ground mandrels in .0005 increments. Having the mandrel dead nuts straight, round, and concentric is very important or you’re inducing error into the readings. If the runout is out just .0001 at the face, that equals .0007-.0009 at the tang. So if you don’t have a highly precision mandrel, then it’s not going to guarantee the action is dialed in as good as possible. Just my thoughts. I’ve used some custom ground mandrels when I worked at Pierce and will never use a rod with bushings again.

Yeah, The bushing ones just are too sloppy.

 

[hoz53]

Yeah, The bushing ones just are too sloppy.

i think alex W got the order together for the ones that Warner made.

 

[LVLAaron]

You're gonna need/want them larger than .703

 

[tobnpr]

I recently talked to an industry manufacturer of precision tools (not PTG) and they mentioned offering solid ground mandrels in .0005 increments. Having the mandrel dead nuts straight, round, and concentric is very important or you’re inducing error into the readings. If the runout is out just .0001 at the face, that equals .0007-.0009 at the tang. So if you don’t have a highly precision mandrel, then it’s not going to guarantee the action is dialed in as good as possible. Just my thoughts. I’ve used some custom ground mandrels when I worked at Pierce and will never use a rod with bushings again.

Explain to me how using a precision ground mandrel that has a slip fit at one end of the raceway is "better" when there's two thou of clearance around the mandrel at the other end, given that there's never a precise/consistent ID with mass-produced receivers?

 

[WSnyder]

i think alex W got the order together for the ones that Warner made.

He didn’t at least on the last batch, he advised on the sizing though.

Thread 'Full diameter action mandrels'

Jun 9, 2021

I’ve recently discovered how to check action straightness in actions I’m blueprinting with the old bushing and .500 mandrel and I’m commonly getting .0025-.005 runout right behind the action when it’s shouldered up on the tenon. I’m a little disappointed as I spend so much time indicating and taking light cuts to try and make them perfect. I’ve checked a few custom actions that were anywhere from .006-013!! I had no idea.

I’d like to try some full diameter mandrels to indicate actions in for blueprinting and to more accurately check the customs I’m working on (im hoping they aren’t really...

• Taylor Stratton

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