Picatinny rail

The Picatinny rail (IPAEng|ˈpɪkətɪni or IPA|/ˌpɪkəˈtɪni/) is a bracket used on some firearms in order to provide a standardized mounting platform. The name comes from the Picatinny Arsenal in New Jersey, where it was originally tested and was used to distinguish it from other rail standards at the time. The rail comprises a series of ridges with a T-shaped cross-section interspersed with flat "spacing slots". Scopes et al. are mounted either by sliding them on from one end or the other; by means of a "rail-grabber" which is clamped to the rail with bolts, thumbscrews or levers; or onto the slots between the raised sections.

The rail was originally for scopes. However, once established, the use of the system was expanded to other accessories, such as tactical lights, night vision devices, laser sighting modules, reflex sights, bipods, and bayonets. Because they were originally designed and used for telescopic sights, the rails were typically found only on the receivers of larger caliber rifles. But their use has extended to the point that today the combination of Picatinny rails and accessories are displacing the original iron sights in the design of many firearms, and they can now often be found on the undersides of frames and even on grips.

In order to provide a stable platform, the rail should not flex as the barrel heats and cools; this is the purpose of the spacing slots: they give the rail considerable room to expand and contract lengthwise without distorting its shape. The Picatinny locking slot width is convert|0.206|in|mm|3|abbr=on. The spacing of slot centers is convert|0.394|in|mm|3|abbr=on and the slot depth is convert|0.118|in|mm|3|abbr=on. [http://www.quarterbore.com/library/pdf_files/mil-std-1913.pdf] The only differences between the Picatinny rail and the similar Weaver rail are the size of these slots and the fact that they are standardized. Weaver rails have a slot width of convert|0.180|in|mm|3|abbr=on, but are not necessarily consistent in the spacing of slot centers. [http://www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?p=0&t=2&i=558 Brownells - World's Largest Supplier of Firearm Accessories and Gunsmithing Tools ] ] Because of this, accessories can and are designed to fit on both Weaver rails and Picatinny rails; but most Picatinny devices will not always fit on Weaver rails.

ee also

*Rail Integration System

References

* [http://www.biggerhammer.net/picatinny Picatinny Rail Specifications]
* [http://dodssp.daps.dla.mil DODSSP] U.S. Department of Defense Single Stock Point for Military Specifications, Standards and Related Publications