What tool for centering up action in jig?

B

bigngreen

Guest
Super novice question but I'm looking for the best tool for getting an action dialed in for truing. I've looked at PT&G and have bought some other stuff from them but honestly the mandrel and bushings are a daunting purchase right now but I also hate to compromise accuracy. So the basic question comes down to, is there a mandrel and bushing set up that is as accurate but less costly than the PT&G set up? I really hate to ask this question based on money but that's the way it is!!
 
take this as you will

I am a gunsmith so I want to warn you up front I am biased. If you are going to do multiple actions the tooling might be worth laying out the cash for. However the typical person can get a better deal using a reputable gunsmith to true the action in a lathe by single pointing the threads. Also I personaly believe the Greg Tannel truing system that PTG sells is a much better way to true and action. It is the way to get the threads more true than the tap system since you single point them in a lathe. I have used both systems and tested the diffrence in accuracy and am favoring the Gre-Tan truing jig but am happy with the tap system used on a couple hunting guns of my own just to see. If you do go to a reputable gunsmith and get an action trued in a Lathe using the Gre-Tan equipment I believe you will be more happy with the end result. If you are a DIY guy and do not own a lathe then go for it just know you are buying a tool that is going to improve but not make the action the best it can be. Good luck with your project and have fun.
 
Thanks for the reply! I should have given a little more detail as to where I'm at with the whole process. I do have a lathe and have built an action truing jig similar to what most have made and I've done one action with very good results but my method of getting the action aligned was due more to luck than having the right tools. I'm currently just doing my own and friends work so I really have to be careful where the money goes and every dollar has to count but I want to do it right!! I know you guys are tired of hearing this kinda wanting precision without dollar out lay but I just want to make sure my dollars are being used wisely!!
 
sorry I reread your post and it was my mistake. This site how I understand it is to ask questions just like what you are asking so never feel bad. as far as centering it up I use the .705 bolt raceway reamer. OK I just checked and it costs more than the mandrel so you do not want to buy it since you must either buy a bolt or sleeve the one you have. I know of no system cheaper or better than the mandrel or the raceway reamer. after buying the mandrel bushings for all posible recievers you could buy the reamer and sleeveing a bolt takes some time but is not difficult. I do not think this helps you any but good luck and I hope you find something that works but I think it will be hard to beat Dave Kiffs prices on tools that you know are quality and will last. I own and use all of the tools you are talking about they do what they are supposed to and I have no complaints.
 
JohnsonGunsmith said:
I am a gunsmith so I want to warn you up front I am biased. If you are going to do multiple actions the tooling might be worth laying out the cash for. However the typical person can get a better deal using a reputable gunsmith to true the action in a lathe by single pointing the threads. Also I personaly believe the Greg Tannel truing system that PTG sells is a much better way to true and action. It is the way to get the threads more true than the tap system since you single point them in a lathe. I have used both systems and tested the diffrence in accuracy and am favoring the Gre-Tan truing jig but am happy with the tap system used on a couple hunting guns of my own just to see. If you do go to a reputable gunsmith and get an action trued in a Lathe using the Gre-Tan equipment I believe you will be more happy with the end result. If you are a DIY guy and do not own a lathe then go for it just know you are buying a tool that is going to improve but not make the action the best it can be. Good luck with your project and have fun.
Click to expand...

What are the differences you have seen in accuracy between the two systems?
 
Labounty has a set of three mandrels listed in Brownells that would work for you. Are they as accurate as a bushing system??? Probably not, but out of the three, one is usually a good snug fit in the action and it works.
 
Make it. Turn a 10" piece of stock with a very good finish to .625" end to end. Make sure it isn't moved by the tailstock. Check it with a straight edge after your done just in case it wants to return to a natural bend. Bore some very nice fitting bushings, take your time. They will not be as good as a ground tool but can be close, its up to you. Within .001" should be easy if you are careful. That is a lot of coin for a hobby guy to save.
 
eddief

I must admit I have never done a truly apples to apples comparison in the two methods. When I say this I mean useing same contour barrels same chambers from the same reamer in the same brand stock etc etc. I have done some hunting guns for customers that did not want to invest much in the action but wanted to get the most they could out of their guns. This is when I have used the reciever tap method. mainly because it saves me time since dialing in an action to the ten thousandths takes me longer than it should. Being honest I will sacrifice time and profit to get it right so the other method is an easy quick way to improve the action without the time investment.

Now to answer what you have asked I have done multiple actions both ways and the singlepoint method has almost always out performed the tap method. As far as giving a percentage of improvement I would not know. the only time I know of that the tapout performed some of my others was a customer with a 22-250 specifically throated to his loaded rounds and he worked up a load and shot a reported 3 shot group group of.106!
only 3 shots yes but for a preadator hunting gun that with very small cash out lay that is great. I did not see this and have nothing to back it up just what was reported to me but I know he is very happy and now has the long range prairie dog record among his shooting buddies which works for me. so you can get a great deal of improvement but the above mentioned gun is not typical of the results I have seen but I also ussualy am doing this to a 30-06 or 243 with very light sporter barrels. I hope I answered your question to your satisfaction but I have no definitive proof from a structured test that all variables are considered and accounted for. I just have my experiance with it on multiple guns and barrels which has given me a view of the accuracy tendancies of the 2 methods.
hope that helps
 
One suggestion on truing up the bolt, don't take any metal off the end of the bolt nose. The end of the bolt nose is very thin. Athough it looks good to clean it up, removing metal there is not a good thing as it weakens the end of the bolt nose and can lead to the extractor ripping out of the end of the bolt. Since you have clearance between the end of the bolt nose and the recess in the barrel, there's no need to make the cut across the bolt nose. It will save you grief in the long run. If you rip the extractor out the end of the bolt, there are two solutions, replace the bolt with a Pacific bolt or bush the bolt nose and install either a Sako style extractor or M-16 type extractor.
 
JohnsonGunsmith said:
I must admit I have never done a truly apples to apples comparison in the two methods. When I say this I mean useing same contour barrels same chambers from the same reamer in the same brand stock etc etc. I have done some hunting guns for customers that did not want to invest much in the action but wanted to get the most they could out of their guns. This is when I have used the reciever tap method. mainly because it saves me time since dialing in an action to the ten thousandths takes me longer than it should. Being honest I will sacrifice time and profit to get it right so the other method is an easy quick way to improve the action without the time investment.

Now to answer what you have asked I have done multiple actions both ways and the singlepoint method has almost always out performed the tap method. As far as giving a percentage of improvement I would not know. the only time I know of that the tapout performed some of my others was a customer with a 22-250 specifically throated to his loaded rounds and he worked up a load and shot a reported 3 shot group group of.106!
only 3 shots yes but for a preadator hunting gun that with very small cash out lay that is great. I did not see this and have nothing to back it up just what was reported to me but I know he is very happy and now has the long range prairie dog record among his shooting buddies which works for me. so you can get a great deal of improvement but the above mentioned gun is not typical of the results I have seen but I also ussualy am doing this to a 30-06 or 243 with very light sporter barrels. I hope I answered your question to your satisfaction but I have no definitive proof from a structured test that all variables are considered and accounted for. I just have my experiance with it on multiple guns and barrels which has given me a view of the accuracy tendancies of the 2 methods.
hope that helps
Click to expand...

Thanks for the honest reply. I have not seen the difference in a "hunting" rifle between the two methods, but agree on the single point method being the best way to true up a action in regards to the receiver thread relationship with the center of the raceway.

Soooo many variables in this game have an effect on the end result (the target). It sure would get boring if all us accuracy anal retentive perfectionists figured this all out.
 
Thanks for the replies!! I was searching around and found that Manson Reamers seems to use two tapered bushings to align their tools, any thoughts on tapered bushings vs multiple straight bushings?
 
Make your own alignment mandrel. I did.

OK, I'm in much the same situation as you. I do my actions, maybe someday one or two for my brother in law, but that's it. So I <gasp> made my own. I bought a piece of 1/2" precision ground shafting and a 1/2" reamer. I tried 1/2" drill rod but it wasn't "straight". The precision ground shafting was perfectly straight within the limits of my ability to measure it, which I figured was "good enough". With just a touch from some 2000 grit paper moistenid with oil on the inside of a reamed hole I had what I'd consider a "perfect" fit. So I proceeded to machine some bushings in 0.0002" OD increments. I started with the largest sizes I wanted so if it was a hair too small, I used it as one of the smaller bushings. I spent a pleasant couple of days in the shop playing with my favorite lathe (a cherry 9" SB Model A that's been in the family since new and covered with cosmoline) and had an alignment mandrel setup that works perfectly for less than $50.00.

That said, one must use considerable care when machining the bushings because while they don't need to be a particular OD with accuracy tracable to some government agency, just very small differentials in OD (something like 0.0002"), they need to be as close to perfectly concentric as one can possibly make them. So I center drilled, drilled a 7/16 hole, used a small boring bar and machined it to within .002" of the final size, then reamed it to diameter at low rpm with lots of oil using the 1/2" chucking reamer, gave it just a touch of polish with the oil soaked 2K emery paper and checked it for fit and then concentricity with the 0.0001" dial indicator I use for aligning barrel blanks. If I didn't like the fit (it has to slide with no perceptable play) or it was off by more than half a division on the DTI (~0.00005") I parted it off and did it again. I ended up "wasting" three of them but the rest are as good as I can make them.

When machining the OD, which was of course done with the material still chucked in the 3J right where it was when I bored and reamed the ID, I used the compound set to about a quarter degree off aligned with the lathe axis as my depth of cut feed. I made the final cuts at lowest non-backgear speed with a freshly honed HSS bit, fine feed, and lots of oil. I used the as machined finish which was superb. The OD ended up almost perfectly concentric with the ID as accurately as I can measure. The bushings were made from steel rod off a drop rack (mystery metal - which is where most of my metal archive comes from) but it worked just fine.

Try it, you may like it.

Fitch
 
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