Model 70 Barrel Replacement - A Customer's Experience

Guest authored by pre64win.com customer P. Dawson

This article was written by a pre64win.com customer who kindly related their experience re-barreling a cherished family heirloom rifle.  The article is presented here without editing or revision.  We have added a few comments at the end of the article to help any who may attempt to use this article as a DIY guide for replacing a barrel.

My first barrel replacement on a pre-’64 Winchester model 70.

Disclaimer: Don’t believe anything you read here and don’t try any of this ever. You have been warned.

Blaine Rorabaugh was a Navy Sea Bee stationed in the South Pacific during WWII. He was also my maternal grandfather and perhaps the most colorful person in my childhood memory. When he died in 1978, I inherited his 1957 Winchester model 70 chambered in .30-‘06. It would be 17 years before I took custody of his rifle. A trip to the range was scheduled, and a group formed on a paper target. It became immediately apparent that this gun was not living up to its reputation for accuracy. The gun was carefully stored for over another decade before I took some interest in improving its performance.

Although the gun was well used, it appeared to be in pretty good shape on first glance. A borescope, however, showed heavy pitting throughout the barrel bore. I suspect this gun was not stored properly after my grandfather’s death. In any case, this barrel would never again shoot the kinds of groups that inspire confidence. As I searched the interweb for replacement options, I stumbled across a jewel of a site at pre64win.com. Lock your credit cards away before visiting this site. They have a lot of information on these guns, with complete rifles and original parts of varying conditions for sale. They seemed to welcome inquiry, so I composed a short note stating the nature of my problem and asking how to go about repairing it. When I woke the next morning, an apparently knowledgeable guy named Justin had replied to my inquiry in startling detail. He had barrels in stock that were in far better condition than mine. 

The barrel on this gun has a threaded tenon that rotates into the receiver on assembly, and the barrel is notched at 3 o’clock to accept the extractor on the bolt. My primary concern was if the barrel would index properly to the receiver when torqued into place. Justin responded, “… replacing the barrel with another original barrel is usually very straightforward with no complications. Model 70 barrels almost always torque correctly with proper indexing, and 9 times out of 10, they will headspace correctly to the bolt as well.” He had earned a sale, and given me a plan.

A second inquiry to Justin resulted in a tool list and other advice. The tools would exceed the cost of the barrel by multiples, but my local gunsmith was booking six weeks out, and I was on a mission. The barrel was ordered, and the first Brownell’s order was placed. The barrel arrived in a few days, and in advertised condition. There was a “24” stamped into the front sight dovetail, which was also the approximate barrel length in inches. It was nearly 3 inches longer than the barrel I was replacing, but all of the features required for mounting were in the right spots. Score. The borescope found a lot of copper in the bore along with some localized pitting, but after a bit of bore cleaning I had convinced myself that the replacement would be worth the effort.

I photographed the receiver and barrel from every angle for reference, but the extractor slot would be the final determinant for proper indexing. There appeared to be an index mark at precisely 6 o’clock on both barrel exteriors, but with no corresponding mark on the receiver. A Sharpie would solve that problem prior to disassembly.

The action wrench that had been ordered clamps onto the outside of the receiver and has no easy accommodation for torque measurement, so I built a tool to engage the inside of the receiver on one end and a ½ inch drive socket on the other. The tool had a functional torque limit of about 70 lb.-ft., and the receiver seemed to be laughing at me when the tool started to bend. I would need to wait for the proper tool to remove the receiver. In the meantime, the parts would be soaking in penetrating oil.

“Give me a lever long enough and a barrel vise, and I will remove the barrel from a Winchester 70.”   ~Archimedes, slightly paraphrased. 

The first shipment of tools arrived on Saturday morning and I mounted my new barrel vise to the workbench. The inside of a toilet paper roll would be a rather unsophisticated layer of protection between the vise and barrel finish. The action wrench was very robust, and fit the receiver precisely and securely. A six foot cheater handle would have been helpful in place of the pitiful twelve inch handle that was welded in place. A full body workout complete with involuntary noises ensued for about the next 40 minutes.

So as to spare my own embarrassment, I won’t share the final chain of mechanical advantage required to loosen the barrel. Let’s just say it involved at least multiple levers, an inclined plane, and a pulley system. I’m estimating breakaway torque at well north of 250 lb.-ft. My unanchored workbench finished nowhere near where it was when I started, and may have been suspended in midair at some point. When the assembly finally loosened, the receiver unthreaded easily from the barrel. There was no observable damage to the exterior of the old barrel, so the toilet-paper-insert-barrel-protection-method was verified, if not dignified. The receiver and new barrel threads were thoroughly cleaned with mineral spirits and compressed air, and anti-seize was applied judiciously prior to assembly.

My receiver insert would be used to measure torque on assembly, if only to determine an insufficient amount for proper indexing. I started at 30 lb.-ft., and increased in intervals of 10. To my surprise, when 70 lb.-ft. was applied, the assembly was clocked precisely by every measure I could find. The bolt engaged perfectly, and a once-fired brass was easily chambered and extracted. Things were going well.

I’ve never measured chamber headspace in my life, but this seemed like a prudent project on which to start. A set of headspace gauges would be engaged to properly estimate the chamber clearance. The three gauges in the set represent a total spread of .010 inches, so there is a relatively precise window of acceptable operating conditions. The gauges used properly with a naked bolt and in the following sequence, provide this summary:

While awaiting arrival of my gauges, I stumbled upon an AGI Winchester 70 trigger course on YouTube. It was way better than I thought it would be, and gave me some items to work on while my remaining tools were being shipped.

When my headspace gauges arrived I began my measurements in a fit of enthusiasm. The bolt closed easily on the GO gauge. Good result. The bolt also closed easily on the NO-GO gauge. Not a good result. The bolt did NOT close on the field gauge. This was not the overall result I was hoping for, and meant some real gunsmith work would be required to restore the headspace dimensions. What next? It was time to run some ammo through the gun and check for changes in performance.

A reliable optic was mounted to the receiver and boresighted to get my shots on paper. A box of factory ammo was opened and the first round was loaded. A hole formed 2 inches to the left of center. The brass was ejected and inspected. The primer strike was solid and no case distress was apparent. The second round landed ½ inch to the right of the first. Again the primer strike was normal and brass was not distressed. The third shot formed a keyhole with the first, and this part of the project was declared a success.

There are more improvements to make on this rifle. But for now, the barrel replacement was a great first step. I know my grandfather is pleased.

We want to thank Phil for this great article and for sharing his experience re-barreling his rifle. For the most part we think he did things exactly right.  We would only add these few comments:

1. Barrel replacement affects the most critical aspects of your rifle action. Errors in the installation of the new barrel, or in verification of the headspace, can result in unsafe conditions. If you are unfamiliar with this task, please consult with a qualified gunsmith before firing your rifle.
2. Do not attempt to separate the receiver and barrel, or re-torque a new barrel with anything other than the proper barrel vise and action wrench.  Improper tools may result in hidden damage to your receiver.
3. Verifying your rifle's headspacing is a very simple process, but also a critical one.  If you do not have the proper gauges or are uncertain about their use, please contact a competent gunsmith to perform your headspace check.