Action truing

P

PEI Rob

Guest
I have read from a well respected smith that the Savage action threads and lugs are cut with the same mill set up and are true to each other. However, the face is not touched during that step but it was deburred by a grinder when the action was still just a tube so is not true.

So we have an action that the only real issue we can work on is the face being around .003" out. Is there a quicker way to true the face than by using a mandrel and action jig and do all 3? Do you think facing and threading a piece of stock in the chuck then tightening the action onto that, then simply face the action would be an improvement? Picture a threaded stub sticking out of the chuck and the action screwed onto that until the lugs bottom out.

I'm not talking about truing anything else but the lugs, threads and face to each other, the bolt body is not being considered here for a reason.

Cheers,
Rob
 
Truing

If the luggs and threads are indeed true with the raceway, and only the face is out, why not chuck a piece up, face it square, thread it and relieve it so the action will screw on it and the face will butt against the lugg abutments in the action. You then take a small tool and face the action face dead square.
In the mean time, you will be able to see how truely straight the action is with the threads and lugg seats..........jackie
 
Same here .
Trued%20action.jpg
 
I would like to know what sort of fixture is used to set up to machine the threads and the locking lug seats. It seems unlikely they would be set up on the bore of the receiver but I don't know. As Jackie mentioned, with the receiver screwed onto your fixture and a mandrel inserted into the bore, you will be able to check on bore/thread/seat relationship. Regards, Bill
 
The fixture is basically a tall V block that orients the receiver via the raceway. This means that it is located from the o.d. of the receiver as far as centering, and from the raceways as to the orientation of machine cuts.
 
That being the case, the threads and locking lug seats are aligned with the OD of the receiver (providing the receiver is mounted properly in the fixture. Not necessarily a given) and NOT the bore. If, prior to mounting in the fixture, the action was mounted on a mandrel and turned or ground between centers (an unlikely scenario), the threads and locking lug seats would have a better than fair chance of ending up aligned with the bore.
In any case, with the face of the receiver machined to be perpendicular to the axis of the threads, everything would work out quite well providing there was enough clearance in the bolt body/ receiver fit to allow the lugs to contact well. There usually is and of course, the Savage flopping bolt head might play a part in allowing self-alignment.
I personally think the Savage action should be treated much as one would a Remington as far as truing is concerned. Regards, Bill.
 
One reason I ask is because of the big name pre-chambered, pre-threaded barrels available these days. If we true a Savage action like a Rem, the threads will need clean up to run true. This extra diameter would make for a looser barrel thread fit. If we true the face to just the threads and lugs knowing the bolt head floats to compensate for the raceway misalignment, the barrel fit will be better. Not sure which point is more important in the Savage. On a custom barrel fit I use the jig.

Cheers,
Rob
 
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The looser fit does not harm accuracy... when the V threads are tightened they self align... a loose fit is better than tight ... at least that is my belief...
 
I was faced with this quandary when fitting a barrel to a Savage action of my own recently. I wanted to be able to use the original barrel so couldn't re-machine the threads too much. I elected to face the receiver much as described above. Measuring to the boltface showed the bolt head to be not parallel to the face (by nearly .0015"). So, I used fine India stone to hone the lugs until the bolt face was parallel to the receiver face. I then gave the lugs a quick lapping and checked the face again with the striker in place and the action cocked. It is now perfect. I was able to fit my 8" twist 22-250 barrel and still have the option of using the factory 308 barrel. Not normal BR technique (no hand fitting allowed) but it seems to work OK. By the way, I did upgrade the recoil lug as well. Actually, one could upgrade the Savage lug with a common flat washer and a file but I elected to use a RPA lug I had in my toolbox.
The Savage factory threads would give Dennis a warm feeling since they are quite loose. I would say they are certainly no more than a 75% thread; if that. I screwed up the threads on the replacement barrel by fitting them pretty close. I also eschewed the factory barrel nut and fitted the barrel conventionally. Regards, Bill.
 
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