Gun Reports - Special Reports
Excess Headspace in the 1903 and 03A3 Springfield
June 5, 2012
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Historically, gun people are quite conservative. Look at how long it took for the percussion lock to become accepted, not to mention the in-line percussion blackpowder rifle such as the Knight and others.
In order to correct excess headspace in the 1903 and 03A3 Springfield, the textbook method has always been to set the barrel back one turn, or approximately 0.100 inch (03 barrel tenons have 10 square threads per inch), and then ream with a finishing reamer until a headspace gauge shows acceptable headspace. This procedurethe way Granddad did itleaves unsightly gaps in the fore-end inletting, requires an expensive chambering reamer, and requires an educated guess as to how much metal to remove in order to rotate 360 degrees and arrive at the index mark with a nice crush fit.
Why not eliminate the feed cone with its extractor notch and proceed as we do with the Model 93 to 96 Mausers?
I believe the U.S. Army committee that designed the 1903 Springfield put that feed cone there just to get around some of Mausers patents. The angle is too steep to funnel the bullet into the chamber mouth, and it only looks like it might alleviate jams. It doesnt strengthen the lockup, and machining it off doesnt remove any threads, so the strength is still there.
A friend showed me a brand new rifle he had just purchased. It was made in England, and in all practical aspects the action was an exact replica of an 03 Springfield, and Hey! Guess what? It had a flat, pre-98 Mauser-type breech face.
After seeing no feed cone in a new commercially made rifle, I decided to do a little research
Now, lets take a rifle with a bolt that closes easily on the no-go gauge (when using head-space gauges, always apply a light touch when closing the bolt) and go to work correcting the excess headspace. First, clamp the barreled action in a padded vise with the muzzle pointing up. Remove the extractor claw and striker assembly from the bolt, and place the bolt back in the receiver.
Now make about a half-dozen small disks out of 0.002-inch brass shim stock. These disks should be the same diameter as the head of a .30-06 shell. Place one 0.002-inch shim and the go-gauge on the bolt face and gently close. Keep adding shims and repeating the process until the bolt doesnt close. Now add up the 0.002-inch shims or mike them. This will tell you the total space between the go-gauge and the bolt face. Make a note of this measurement.
Now remove the barrel from the receiver with a pressure yoke barrel vise (easy to make or buy from Brownells), then set the barrel up in a lathe with a steadyrest. Face off the feed cone even with the bottom of the extractor notch. Then face off the amount you measured with the shim brass disks, minus
Screw the barrel and receiver back together and check your work with several brands of factory cartridges (with the striker still removed). If you were over zealous and removed too much metal, its all right to install a thin steel shim between the shoulder and receiver ring. (Dont try the latter on a Model 98 Mauser.) If youre happy with the way it chambers several brands of factory shells, the job is finished and you can stamp a new index mark on the barrel.
Obviously, you wouldnt use this method of breeching on a custom barrel with a front sight ramp, or one with a rib milled integrally with the barrel. You would remove 0.100 inch from the barrel shoulder and the feed cone to bring the barrel 360 degrees back to the index mark. Then ream the chamber enough to restore proper headspace.
I dont think I would flat breech a 1917 Enfield, because it would remove part of the thread and maybe weaken it, but the very similar Pattern 14 Enfield, chambering the rimmed British .303, has a flat breech face. Ive had no experience using this technique on other rifles with funnel-shaped breechesthe early Model 70s and Savage Models 40 and 45, for exampleso I cannot offer comments or advice on these.