WALENTINE'S CORNER
Email: SGM(R) Jack Walentine
The Caliber .50 Inbore has been around since the early 1980s. First made for the 90mm gun on the M48 A1/A2/A3 tank, the Inbore has evolved to fit most tank guns world wide from 73mm to 120mm. Several manufacturers have made Cal.50 Inbores as well as versions in 22 cal, 7.62mm, 20mm, 25mm, 30mm and so on. The WALENTINE Cal.50 Inbore, initially produced for the US ARNG, is still around today in many units as well as other versions of the device.
The Caliber .50 Inbore is an accurate piece of equipment if certain criteria are met and maintained. Some of these criteria are as follows:
1. Maintain the Inbore properly IAW the operators manual. If you don't have a manual, email/fax us. (gunmasters@msn.com/fax: 843-497-5783).
2. Make sure your weapons maintenance personnel (ORG/DS) check the Inbore prior to live fire to include headspace, firing pin protrusion, firing pin hole erosion, firing pin spring pressure, chamber pitting, throat erosion, barrel wear, etc.
3. Have your weapons folks check the chamber and throat. If the Inbore has not been properly throated for M903/M962 SLAP-T, it (the SLAP/SLAP-T) will not chamber.
4. Throat erosion and SLAP/SLAP-T throating can be related. If the Cal.50 barrel is not properly throated for SLAP/SLAP-T, accuracy will suffer.
5. Tight is better! When you chamber the Caliber .50 Inbore (Into the main gun), you should feel significant resistance when the front "O" Rings engage the main gun bore. If the device chambers too easily, there will be excessive gun jump/wobble at the muzzle and accuracy will suffer. Check the "O" Rings often. They need to be replaced if they are cracked or worn. If you need "O" Rings, email/fax us and we will supply them at a minimal fee.
6. Once the Inbore is tight in the main gun chamber, ensure that the main gun breech block has good contact the cone nut on the rear of the Inbore. Make sure all Inbore buffer springs are properly engaged.
7. The Action. If your Cal.50 Action is beat up, accuracy will suffer. Any Bench Rest Shooter can explain why the action needs to be in good shape. If you need help with your Cal.50 Actions, let us know.
8. Shoot the Inbore within its limits. The Cal.50 Inbore is accurate out to 1500 meters with M20 API-T and M17 Tracer under good wind conditions. If you have 25 knot cross winds, accuracy will be poor. If you shoot M17 Tracer, be aware that prior to 1995, the specs for the rounds were a bit less than the are now and there will be more "round to round dispersion". M962, SLAP-T is good out to 2000 meters. Moderate wind has less affect on the SLAP-T round with its high muzzle velocity and small mass. The downside to firing SLAP-T is sensing. The round travels at about 4000 feet per second. The tracer is hard to see on bright days unless you are directly behind or over the firing vehicle.
9. Use the correct computer setting on the firing vehicle. M1, M1IP, M1A1 Abrams: Fire M20 API-T and M17 Tracer using SUBDES 50 with HEAT or SABOT indexed. Fire M962 SLAP-T with HEAT indexed with SUBDES 0. For the M1A2, fire the M20 API-T and M17 Tracer with SUBDES M20 indexed. Fire M962 SLAP-T with M830 HEAT-MPT indexed.
10. If you're not hitting targets on good condition days, check all of the above for problems, then call us if you need help.
Sunday, 14 October 2007