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From Truck to Truck There is a large amount of data in the form of colour photos involved in this comprehensive description of the manufacture of a rifle barrel, so we have broken it up into a number of smaller pages. You can also click on the smaller 'thumbnail' pictures to view a full size picture. Delivery and Cutting Quality control started before the steel left the mills. Test certificates are issued and the steel is now tested and compared to specification. Steel is cut to various lengths depending on the type of barrel being manufactured from 24" Sako to 31½" target barrels. Blanks are loaded into computer controlled electric fired stress relieving ovens and soaked in a controlled environment for a total heat up – cool down cycle of 21 hours. The program cycle is determined by the data from the test certificates. Barrels are cleaned, faced and centred. Every piece of barrel steel is inspected and a decision made as to which end will be the muzzle and which the chamber. All work from here on starts from one end of the piece of steel. Drilling and Reaming Deep hole drilling is conducted on a Howe twin spindle machine using a single flute drill where the barrel spins and the drill remains stationary except for being fed forward at a feed rate of 2/10" to 5/10" of a thousandth of an inch per revolution while the barrel spins between 2000 and 6000 rpm dependent on calibre. High pressure cutting fluid is supplied to the drill at up to 1600 PSI 11,000 KpA Drills from .161" to 28 mm are used for barrel and action manufacture and some limited engineering work not associated with firearms, deep hole drilling being a speciality of M.A.B. Engineering. At this stage, the barrel blank is stress relieved again. More cleaning. Reaming a few more thousandths of an inch from the inside of the barrel brings the final internal dimension to size. The barrel now is held stationery while the reamer is rotated and pulled through giving a mirror like finish. Pressure cutting oil, fed up the inside of the reamer, flushes out the swarf as the reamer does its job The adage "cleanliness is next to Godliness" was drummed into me by my mother from when I was a child, but she never realised how true that was until you apply it to barrel machining. A barrel is cleaned and inspected by hand up to 16 times before the customer gets it. Rifling Button Rifling – the barrel is once again cleaned scrupulously and solvent dried. Then it is lubricated with a Teflon in suspension which goes in wet and is allowed to dry. A double button system is used in M.A.B. where the rifling section is some .011" bigger than the reamed hole in the piece of steel and the following smoothing (or burnishing) section just touches the top of the lands after they are pushed up or deformed or swaged – into the barrel. A hydraulic ram pushes the button through the barrel, while the push rod is turned at the twist rate required. Clean again, inspect Quality Assurance. Insert plugs and inert atmosphere. Stress relieve again. Clean again, inspect and saturate in rust preventative (CPD 32). Batches of 25 are maximum as beyond this, quality assurance may go down because of boredom on the operator’s part. As much expense goes into the working conditions of the staff as with the equipment and tooling as the final products are only as good as the persons driving the machines. Their attitudes reflect the quality of our products. Profiling All exterior profiling was conducted on the hydraulic sigmatic copying lathe where a stylus followed a template (an extended old barrel was often used for a one off). This machine has since been semi retired and is only used for development work or one off specials. Today a Mori Seiki CNC – computer controlled lathe stores programs for hundreds of profiles and by the flick of a switch (ha ha), can change from Sako to MAB to BSA to target barrels. The CNC not only does the job faster without an operator (except for loading and unloading) but is consistently more accurate on the sizing and less stress is created by the infinite ability to adjust speeds and feeds of the titanium cutter to match the steel and profiles being produced. Inspection and Dispatch Final inspection for straightness is conducted by eye using the light box principle of a century ago. The shadows are monitored while the barrel is slowly rotated. No straightening takes place on M.A.B. barrels. They are produced from straight drilled holes and kept that way by skilled operators. Stamping to match the orders and sizing of the barrel. Linishing of exterior is conducted by hand and this finish cuts down the work needed by your gunsmith while fitting as only a touch-up is needed before blueing or final polishing. By request or if the barrel is a stainless steel target Games Special, it can be then glass bead blasted to give a stippled anti-reflective finish. Final inspection, packing and wrapping, ID tag and finally shipment.
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