How to Hand Lap a Rifle Barrel Youtube

Lead lapping a rifle barrel

Category: Do it yourself
Published: 5 September 2018 by Øyvind Flatnes.
Views: 8509

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Start by preparing the barrel.

It's advised to slug the barrel before you start lapping.

Make sure the lead is hot.

A cotton patch works fine as a seal.

Warm the barrel before you cast.

Hor lead is being poured down the barrel.

The lead is cooling.

Push half the lap out of the barrel and apply abrasive.

Coarse and fine valve grinding compound.

The masking tape shows how far you have pulled the lap.

Apply abrasive to the lower part of the lap.

A lead lap ready for replacement.

With the technique called lead lapping pitted or damaged rifle or pistol barrels can have new life. In short, the process involves casting a lead slug into the barrel. Apply abrasive to the slug (or lap) and work it back and forth in the barrel until the bore is polished.

Note: Watch a video showing the lapping process at the bottom of the article.

Lead lapping can have many positive effects – and one possible negative. The most obvious advantage is that pitted barrels are smoothed. If a barrel has a worn muzzle – for example, caused by cleaning rod wear, the rest of the barrel is opened up to the muzzle diameter. After a lead lapping, most old barrels perform better. It is a prerequisite, however, that the barrel has intact rifling before you start. A possible negative effect is that the diameter of the bore might become larger, and you may have to increase the bullet diameter accordingly.

Although a 11.77mm (.46") kammerlader barrel from 1863 with hexagonal Whitworth rifling is used as an example in this article, you can lap just about any gun barrel – from air and hunting rifles to muzzle-loading pistols and modern semi-automatic pistols.

Preparing and slugging the barrel.

Start by preparing the barrel. Remove the breech plug in muzzle-loading barrels. In breech-loading barrels you must make sure you can insert a rod from the chamber end. First you should slug your barrel. The slug provides you with exact measurements about the barrel's bore and land diameter. To slug the barrel, simply drive a lightly oversized pure lead plug through the barrel. This leaves you with a perfect imprint of the bore and rifling. Measure the land to land and bore diameter and save it for future reference. By using the measurements as a baseline, you can control how much metal you remove from the barrel. To slug the barrel, clean it and run a lightly oiled cleaning patch down the bore. Fasten the barrel vertically in a vice ('or vise' for you Americans) and place a slightly oversized lead plug (for example a roundball) over the muzzle. Start the plug into the muzzle with a wooden or rubber mallet. Drive the plug through the barrel with a dowel, cleaning rod or similar. Make sure not to damage the slug as it exits the barrel.

You may also want to slug the muzzle and breech. This will reveal if, for example, the muzzle has a larger diameter than the rest of the barrel. To slug the muzzle, follow the instructions above, but stop when the plug is a couple of inches down the barrel. Drive it out again from the other side. Do the same with the breech. Measure the slugs and keep a record of the measurements.

Once you're done, clean the barrel and finish with a dry patch. The barrel is now ready for lapping.

Preparing the rod and melting the lead

Find or make a sturdy steel rod, preferably with a ball-bearing handle. A good handle is important, because it may require some force to work the lap. In this example, the lap is cast onto a brass jag. The raised head of the jag makes sure the lead slug sticks to the jag when you pull the rod back and forth. If you don't have a jag, a threaded steel tip or simply a loop works fine too.

While you prepare the rod, heat the lead pot. The lead should be as hot as possible when you pour it into the barrel. I prefer at least a temperature of 1000 °F or 550 °C. Pure lead will work well in most cases, but sometimes a harder alloy is required. While the lead melts, wrap a cotton patch tightly around the rod and secure it with a non-synthetic thread. As well as sealing the bore and preventing the lead from spilling, it also creates the base of the lap. Position the patch so that it will cast an approximately 1" long lead lap. If the first lap goes smoothly through the barrel, you can increase the length the next time.

Casting the lap

Heat the barrel gently before you cast the lap. A warm barrel minimises voids and irregularities in the cast. I place the muzzle an inch or so over a hot-plate and let it heat for a while. (The barrel is never in contact with the hot-plate.) For the same reason, dip the tip of the rod into the molten lead just before you pour the lead.

When both barrel and tip are hot, insert the rod in the barrel and fasten the barrel vertically in the vice. Use gloves! Adjust the rod so that the tip is slightly below the muzzle. If the muzzle is exceedingly worn you can cast the plug further down the barrel to get a better imprint of the rifling.

Pour molten lead down the muzzle until the tip of the rod is covered. Make sure the lead doesn't flow over the muzzle. This will create a mushroomed plug which is impossible to pull down the barrel. Let it cool for a while and fasten the barrel horizontally in the vice.

The lapping

Drive the plug out so that half of it extends out of the muzzle. Do not to drive it all the way out. If the entire lap accidentally slips out, make a new. Mark the rod with masking tape or similar at the breech end. This serves as a guide that prevents you from pulling the rod too far out.

Apply a generous abrasive to the lead lap. Valve grinding compound works fine. Then pull the lap through the bore until half of it is exposed outside of the breech. Apply abrasive and mark the rod with masking tape a couple of inches behind the lap, so that you see when it's approaching the end. If the plug is hard to drive back and forth, it helps adding some oil in the barrel.

Then the tedious work of working the lap back and forth begins. Apply more abrasive to the plug regularly. When you feel the lap is getting worn, clean the barrel and cast a new. You notice this when it becomes easier to push and pull it in and out. A barrel may need several laps before you achieve the desired result and the process may take several hours. Remember to slug the barrel and check the diameter regularly.

When you're done, make sure to clean the barrel well. Get rid of all traces of abrasive. Wash the barrel inside and out with hot soapy water. Once you're done, assemble the gun and bring it to the range. The target will reveal if the work has paid off.

How to Hand Lap a Rifle Barrel Youtube

Source: https://svartkrutt.net/lapping

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