Pre-fit differences

[rbp75503]

Could some one please clarify some terms used by different barrel manufacturers. What is the differences of a pre-fit barrel which is a short thread shank and a barrel which the chamber is cut .005" to .010" short? What is the technique for each to correctly time and headspace the barrel?

I believe the short cut chamber can be headspaced with a pull through reamer until the bolt closes. I am not sure of the technique for a short thread shank barrel.

Thanks
Bob

[foxx]

I am not sure you are clear on the fundamentals of the Savage system and differences with more traditional makes such as Remington. Forgive me if I show my own ignorance here.

All "prefits" are designed to work on one of two different savage actions, LARGE and SMALL shanks, using a barrel nut as a lock nut to adjust and set the HEAD SPACE. Using this technique, you can set the headspace without the need for additional tooling/cutting/grinding etc. The shank threads are simply threaded further down the barrel so that the barrel and nut can be spun as deep as necessary to set the headspace against a "GO GAGE", and then locked into place by tightening the barrel nut against the face of the action. There is no shoulder cut into the barrel itself. Instead, the nut acts as a moveable/adjustable shoulder.

THe difference between LARGE and SMALL shank is just the outside diameter of the cut threads. Most actions call for SMALL (standard) shank. It's not an option. The action is either built from the factory with a large opening for the barrel or a small opening. Typically, only TARGET actions are large or certain MAGNUM calibers, such as 270 WSM. The rest are considered SMALL or standard shank.

Beyond that, a shooter may choose to have the THROAT reamed long or short so as to match whatever length of bullet seating he wants. For example, if you want to shoot longer than standard .223 cartridges, you will ask the barrel maker to ream the throat a bit longer (whatever your specs might be) to allow the longer bullet. Do not confuse LONG THROAT with LARGE or SMALL SHANK. Those are two different things.

IF you want a more traditional barrel that has a shoulder (no nut), THEN you would have the barrel threaded and contoured in such a way that you do not use a nut. It is threaded up to the shoulder and then custom reamed to for the proper head spacing. I do not know anyone who does this with the Savage rifle. It is too easy to simply get "pre-fits" and use a barrel nut to set your headspace yourself without machining tools.

[rbp75503]

Thanks Fox for the detailed info. Unfortunately I am looking for a barrel replacement that is not for a Savage action. The 2 barrel manufacturers that I am looking at offer a short thread shank or a short chamber prefit.

[foxx]

Gotcha. I was afraid of that. :)

I am with you, then. I am only familiar with the concept of the short chamber prefit where you personally finish the reaming as necessary for proper head spacing.

Hopefully someone else can answer your question.

[Robinhood]

Pac Nor has a great reputation and works with you on many different rifle brands and models. Their barrels are also known for high quality.
Check out their "Prefit" information page.
http://pac-nor.com/prefit/


Then there is the barrel nut option.

[rbp75503]

Pac Nor has a great reputation and works with you on many different rifle brands and models. Their barrels are also known for high quality.
Check out their "Prefit" information page.
http://pac-nor.com/prefit/




Actually Robin I am looking at Pac-Nor for a 1903 Springfield pre-fit barrel to replace a Criterion Barrel which is not performing up to my expectations. However, Pac-Nor prefit is short thread shank and I am wondering if that is the same as a short chambered barrel. I have the capability of headspacing via pull-thru finish reamer. If a short thread shank requires a lathe I do not have that capability.

[drybean]

I believe that you have to cut the shoulder on the barrel to set the head space
That is what I had to do on my Pac Nor prefit for a ruger varmint rifle

[Robinhood]

I believe that you have to cut the shoulder on the barrel to set the head space
That is what I had to do on my Pac Nor prefit for a ruger varmint rifle

Exactly. The chamber is finished they just leave some material on the recoil lug face area on the tenon. I have not inquired but would be surprised if they would not be able to cut it for a custom barrel nut.

[rbp75503]

Thanks folks for the replies and info. It looks like I just might send my action and have them do the fitting and be done with it.

[FW Conch]

I wonder if a short thread shank barrel is to provide the ability to time open sights, barrel devices, or to provide for the option of a barrel nut or shouldered barrel? Of course headspace would have to be taken from there. Sounds like a Gunsmith process?

Sending Your action in to have the barrel fitted to it is a sound idea, IMO, unless You know a good smith You want to give the business to.

[rbp75503]

I wonder if a short thread shank barrel is to provide the ability to time open sights, barrel devices, or to provide for the option of a barrel nut or shouldered barrel? Of course headspace would have to be taken from there. Sounds like a Gunsmith process?


It looks like Kreiger and Pac-nor cut the shoulder short and then would require it to be put in a lathe to get the proper headspace. The timing mark, breech cone, extractor cut are machined and the chamber is fully cut to spec.

Criterion barrels are machined with the timing mark, breech cone, extractor cut, and front sight area cut and the chamber is cut short. Then all you have to do is use a pull-thru finish reamer to finish cut until the bolt closes.

I went ahead and ordered a barrel from Pac-Nor and with fitting of the barrel to my action