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Hey Aladin!!
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Aladin, in case you haven't noticed it, we have a hot debate going up in the Varmit Forum about lead tips and cast bullets melting in flight from "air friction."

Personally I think it's a lot of horse feathers, but I would value YOUR opinion up there if you'd like to contribute. I know you've somewhat specialized in seeing just how FAST you can push a cast bullet, whereas I haven't followed that path.

If you've got time, check out this thread above and give us benefit of your experience.

Pecos 45
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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I see the ol' Kornel is out selling copies of the rag again-- getting the natives all covered with the melting lead of bullet tips. As to bullet tits melting-- photo's of soft lead tips on jacketed slugs have shown those points slumping to the inertia of acceration AND the buildup of air pressure going down the bore. Go figure the effects of say air pressure with that slug making that trip in less than 2 thou of a second. That was my understanding as to why polymer tips can into use along with magazine contact etc distorting those noses.

Cast bullets do not melt due to air friction-- in reality if any cast metal is displaced it's due to the combustion gases going past the bullet surface, which starts in the gun's throating and continues up that bore should enough surface be blown away initially. Same concept as cutting metals and such like with a jet of water which is done commercially. In this case the agent is compressed combustion gases-- which can damage even the gun action should the case head let go and route gases thru the port which vents such. Yet leading originates with gas blowby from the rear, an event which is negated by proper bullet fit to the throating, obturation if thats taking place and good lube-- which is the finger in the dike so to speak.

So lets assume the bullet's in the bore sans any gas cutting-- leading can occur do to bullet surface being too soft to hold the rifling at that speed- shearing if ya will. Those short ribbons of lead coming out at cleaning could indicate this.

Another factor is the bore's UN-even groove/bore dia-- which is common and one of the major reasons your gun won't shoot well as you up the FPS. I've seen bores with over a thousandth variation down that tube-- picture the case of the cast bullet going thru that scenario. It starts out being swaged actually to the groove dia-- a few inches down the dia chg's to another thousandth larger. What happens-- the bullet looses it's grip and skids-- which deposits lead. What happens to this lead with the next shot-- part melts/vaporizes into the air. I had a guy come over one day and asked if I was shooting BLK in my 06. Nope-- just leading up the air, those puffs and clouds of smoke being vaporized lead from deposits already in the bore [the load >2700 with bullets slightly too small to hold]. No lube made or possibly made will negate this effect-- the bore and bullet have a limit as to speed and fit, not even mentioning the roughness some bores have per throat erosion and tooling marks.

She boils out to this: the cast barrel MUST be superior as to dimensions to produce the same accuracy as a jacketed load WITH the speed dial turned up. No matter how good you make the slug, no matter the lube-- it's mission impossible with some tubes before you even start out.

Now my good Pecos, note I posted this at the cast forum. I too doubt air resistance melts lead points and least of all polymer tits. But I've no proof one way or the other. It'd pass muster if it melted A-tall-- which it might under some of the air qualities we see today. Thing is- the corny Kornel has done his job for that rag-- generating controversy and hence interest. What that horses' south end set out to DO.
 
Posts: 1529 | Location: Central Wisconsin | Registered: 01 March 2001Reply With Quote
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Good post, Aladin. Even a simpleton can understand your words. Thankee!
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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