Mosin Nagant bore slugged - left, right bore image.

Slugging The Barrel For Optimum Accuracy

Winchester Model 73 in .44-40
Winchester Model 73 in .44-40

Q: I own an early Italian copy of the Winchester Model 1873 in .44-40which is giving large groups with Lyman’s bullet No. 42798, a 205gn flat nose. From the mold the bullets dropped at .432inch when poured of my 1:20 tin-to-lead alloy and I sized them to .430 as most manuals list .430 inch diameter as the nominal groove diameter for .44-40s. It has been recommended that I should slug the barrel before reloading. Can you tell me how to go about that?
Henry Kenna

A: Individual tolerances vary greatly in rifles chambered for the .44-40 Winchester and extreme care should be used in working up maximum loads. Due to variations in groove diameter, it is recommended that you slug your

Mosin Nagant bore slugged - left, right bore image.
Mosin Nagant bore slugged – left, right bore image.

barrel before you start reloading.
This goes double for old Model 1873s and Italian replicas. To drive a lead slug through the barrel, first start it at the muzzle with a plastic faced hammer. have used a RCBS inertia bullet puller for this. Once the bullet is flush with the muzzle, use a small brass punch to tap it a few inches farther in. Then push the bullet all the way through with a close fitting hardwood dowel or a plastic-coated cleaning rod. Whatever you use should be tapped gently and not hammered violently. A soft lead bullet is easy to tap through the barrel, and if you pay close attention you can spot any tight or loose spots in the bore. After the bullet drops out of the chamber, all you have to do is measure it at its widest point to find the groove diameter of your barrel.




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Nick Harvey

The late Nick Harvey (1931-2024) was one of the world's most experienced and knowledgeable gun writers, a true legend of the business. He wrote about firearms and hunting for about 70 years, published many books and uncounted articles, and travelled the world to hunt and shoot. His reloading manuals are highly sought after, and his knowledge of the subject was unmatched. He was Sporting Shooter's Technical Editor for almost 50 years. His work lives on here as part of his legacy to us all.