Home Forums Reloading Big Game Rifles Powder Type and Bore Life

Below is a quote from the Sierra exterior ballistics website (http://www.exteriorballistics.com/reference/rifleinout.cfm). It claims that whether you use spherical or extruded powders makes no difference in bore life. Does anyone have any hard evidence to the contrary?

Some debate has ensued over the merits of ball powders vs. extruded tubular powders. Extensive testing at Lake City Ammunition Plant found �no significant difference in bore life, accuracy wise, when using either IMR propellants (extruded tubular) or spherical propellants (ball powder).� While these comments were made specifically about the 30 caliber and 7.62mm NATO Match ammunition, the same situation will hold true for most other cartridges.

I wouldn't take issue with Sierra over much of anything, as their info is based on pretty good authority; there is likely no significant difference in bore erosion between two powders of similar purpose and similar burn rate that can be consistently measured.

However, the military has developed low heat powders designated for use in machine guns...these barrels get real hot, real quick and are made of special steel to compensate...the lower heat powders do extend barrel life in that application.

Whether "accuracy life" as we speak about it is extended is a different question. Machine gun barrels are considered to be worn out when the bullets start flying sideways and won't fly downrange...that is a different consideration than accuracy we consider suitable for sporting purposes.

But to answer your question...the most relevant relationship between powder and bore life is that the slower the powder, the smaller the caliber, and the more powder you burn per round, the shorter your barrel life will be.

TC

I understand that the military uses Alliant RL-15 for .308 caliber sniper rifles. Is this powder also used for .308 caliber machine guns, such as the M60?

Interesting result since the load data tables indicate that the slower powders produce lower peak pressures.

No wonder I cant find any RL15!

I've no idea if Reloder 15 powder is used in machine guns. Its webpage (http://www.alliantpowder.com/products/reloder_15.htm) states, "Selected as the powder for U.S. Military's M118 special ball long range sniper round."

I found a webpage listing military 7.62mm ammo and the powders used but it seems dated: http://www.inetres.com/gp/military/infantry/rifle/762mm_ammo.html