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Technical information

Reflex Suppressor fixing details

  Unlike a conventional sound moderator which is fixed and aligned to the barrel only by a small thread and thread shoulder, reflex suppressors are aligned at two points on the barrel nearly 8 inches apart. The front of the suppressor is aligned on a spigot at the muzzle (see below) and the rear of the suppressor is aligned on the outside of the barrel by a close-fitting interchangeable bush. Click here to see a diagram. When fitted in accordance with the designer's instructions the retaining thread and shoulder do not contribute to the correct alignment of the suppressor. This means that the thread can be made very nearly the full original diameter of the barrel (-1.0 mm or -0.040" is usually OK).

Muzzle thread and spigot details

  The usual reflex suppressor muzzle thread and spigot detail is a 15x1 mm (or 17x1 or 14x1) metric thread with a long cylindrical "spigot" (F) and a relief cut (G) between the thread (H) and the shoulder (E) - see drawing below. The purpose of the muzzle spigot (F) is to ensure precise alignment in conjunction with the close-fitting barrel bush at the rear of the suppressor.

   With this design the muzzle thread (H) is not used for alignment and the designer advises that the thread should not be a close fit. Click on Owner's manual to see a drawing and detailed fitting instructions. From an engineer's point of view, this is a correct design detail, like a Paramount or RPA receiver/barrel joint.

  We also stock Reflex Suppressors to fit "legacy" rifle muzzles which are already threaded 1/2"x20 tpi UNF, 1/2"x28 tpi UNEF or 5/8"x18 tpi UNF without the locating spigot between thread and shoulder. In this case, we allow a larger suppressor exit aperture for some rifle calibres (6.5 mm, for instance would use 8.5 mm aperture). Other imperial threads including 9/16"x24 tpi and 3/4"x16 tpi UNEF are available to order or sometimes from stock.

Barrel bush

  The interchangeable bush at the rear of the Reflex Suppressor is Delrin for hunting rifles, or brass for military weapons (so it won't melt with sustained full-auto fire). The bush must be bored on a lathe to the correct size to fit each individual barrel.

Suppressor inner tube

  The suppressor expansion chamber has an inner tube which sleeves back over the barrel (so the combustion gas does not touch the barrel). The standard inner tube internal diameter is 22 mm. Click here to see a diagram.

  For barrels larger than 21 mm (0.827") outside diameter (measured at the back of the suppressor, usually 210 mm from the muzzle) we can provide a larger diameter inner tube - 25 mm or 29 mm ID. In fact, we can supply almost any configuration to order, including specific models for military weapons.

Baffles

  Firearm suppressors work by lowering the pressure at which the powder combustion gas is vented to the atmosphere. Suppressor baffles provide a large surface area to cool and condense the combustion gas, lowering its pressure. The more baffles, the better the sound reduction. Each doubling of the number of baffles (say from 4 to 8 or from 8 to 16 baffles) reduces the muzzle blast noise by approximately 3 dB (usually 2 to 5 dB).

  However, with supersonic ammunition there is a point of diminishing returns where the muzzle blast noise is reduced below the bullet flight noise (which can not be suppressed).

  Each extra group of four baffles extends the reflex suppressor by about 38 mm (1.5") and increases the weight by about 80 grams (3 oz).

  For pest control, woodland stalking or target shooting, the T8 model (eight baffles, 660 gm) is a good compromise between sound reduction, length and weight. For highland stalking, where the ratio of miles climbed to shots fired is rather high, some shooters prefer to save a few ounces with a T4 (four baffles, 580 gm). Both models comply with HSE Noise at Work Regulations on a typical 243 or 308 Win stalking rifle.

Baffle hole diameter

  Standard baffle apertures are 7.5 mm , 8,5 mm, 10,5 mm and 13.0 mm. As a rule, the bullet caliber (bullet actual diameter ) plus at least one millimetre gives the exit aperture diameter.

  • 7.5 mm hole takes 222, 223, 22-250, 6mm, 243, etc.

  • 8.5 mm hole takes 6.5mm 270, 7mm, 308 , 30-06 etc.

  • 10.5 mm hole takes 9.3mm, 338 etc.

  • 13 mm hole takes 45-70 etc.

  • The reinforced "magnum" model (stamped "M") for cartridges above 30-06 case capacity has 10.5 mm exit aperture as standard (other aperture sizes to special order).

  The smaller the baffle hole diameter the better the sound suppression, but the difference between each of the above hole size increments is only 1 or 2 dB. In general, it is better to reduce the sound by adding more baffles than risk making the baffle holes too small.

  All rifle bullets yaw a little on leaving the muzzle. The longer the bullet the more baffle hole clearance we need to accommodate this yaw without risk of a bullet grazing a baffle. If a bullet grazes a baffle, it can cause a "flyer" (a shot which flies well out of the group).


Jackson Rifles
Parton, Castle Douglas, Scotland  DG7 3NL

Tel:  (01644) 470223         Fax: (01644) 470227

 

Copyright
21 June 2007

Jackson Rifles is a division of Forge Consulting Ltd,
registered firearms dealer #108 (Dumfries & Galloway)