This Bear Creek Arsenal AR-15 20" 17. HMR barrel has a blowback gas system, with a 416R Stainless Steel finish, and a 1:9 twist. Our AR-15 rifle barrels are made from the finest Chrome Moly Vanadium and precisely rifled for high accuracy at a great price. Use a Bear Creek Arsenal ar barrel in your AR15 next build and experience superior performance back by a lifetime warranty! All finished barrels go through a 100% inspection process. Inspections Equipment includes CMMs and Air Gauges for the bores as well as visual and machine inspection. {{widget type="Magento\Cms\Block\Widget\Block" template="widget/static_block/default.phtml" block_id="42"}}