CS: Target-FMJ v. HPBT
From: [EMAIL PROTECTED] I'm still not convinced that propellant gasses are responsible for melting any significant quantity of lead from the base of a bullet. I used to think that this was a major cause of leading but now I'm not so sure. It seems far more likely to be down to bullet sizing and alloy type rather than the lead actually being melted by the propellant. I would think that any bullet that is larger (even by a very small ammount) than the bore or cylinder mouth is very likely to leave an ammount of it's mass behind, especially when it is made of a relitively soft material such as a lead based alloy. I used to fire 333grn cast bullets from an NEI mold from a Super Redhawk on top of lots, and I mean LOTS, of H110. It was a superbly accurete load for long range shooting. The leading from this load was virtually nil even though pressures must have been right at the upper end of the .44 Mag limit. I've fired lighter bullets with big charges of powder which have left lead on 50% of the length of the barrel even though the pressures can't have been any higher. I'm sure that sizing and alloy type have more to do with it than does bullet base melting. Regardles of what Rob Letham said, and I'm not doubting his qualificatins one bit, I don't think this is a problem with FMJ's. If it were we would have seen it in military rifles, or at least with rifles using military ammo, before now as they surely must work at greater pressures than 9x25mm Dillon. After all shotguns don't get plastic deposits in their barrels from plastic wads or cartridge hulls do they? Another thing that occured. Modern primers use lead as a major part of thier composition do they not? Perhaps under certain circumstances lead from the primers is being deposited in the barrel? Has anyone ever tested for this? Jonathan Laws. -- I don't think comparing plastic to lead is really relevant, I'm not sure what shotgun wads are made from but the plastic is harder than lead and it will have a different melting temperature, shotguns are smoothbored, wads may be undersized, the velocity is much slower etc. etc. I'm pretty sure it does happen in military rifles, to be honest. It's only a small amount of lead, but it only has to be a small amount. Because it happens inconsistently, it can affect accuracy. There are plenty of SS109-type bullets with the weight to the rear of the bullet like an HPBT because they have a steel tip, but they don't shoot as well as HPBT, even if you carefully select the bullets to make sure of diameter and so forth. Like I said I don't pretend to be an expert handloader but certainly I know service rifle shooters in Canada and elsewhere who have looked into that particular aspect and HPBT beats FMJ every time. (Unfortunately in Canada they have to use FMJ!) Steve. Cybershooters website: http://www.cybershooters.org List admin: [EMAIL PROTECTED] ___ T O P I C A The Email You Want. http://www.topica.com/t/16 Newsletters, Tips and Discussions on Your Favorite Topics
CS: Target-FMJ v. HPBT
From: [EMAIL PROTECTED] If the base of the bullet does not melt then why does everyone use HPBT bullets for the best accuracy? Because it's easier to make a jacketed boat tail if you design it so the jacket ends at the top rather than the bottom, and also the propellant gasses can't try to strip the jacket from the core. It also means that the base of the bullet can be thicker if you use a tapered jacket so it deforms less and shifts the weight forward. I don't think that propellant gasses actually melt bullets, if they did I think it would be a problem with military guns that do use boat tails with exposed cores. Jonathan Laws. -- But not with the flatbase bullets that Berger makes, as Andrew pointed out already. Those would be easier as FMJ. Steve. Cybershooters website: http://www.cybershooters.org List admin: [EMAIL PROTECTED] ___ T O P I C A The Email You Want. http://www.topica.com/t/16 Newsletters, Tips and Discussions on Your Favorite Topics
CS: Target-FMJ v. HPBT
From: "E.J. Totty", [EMAIL PROTECTED] --snip-- I don't think that propellant gasses actually melt bullets, if they did I think it would be a problem with military guns that do use boat tails with exposed cores. Jonathan Laws. -- But not with the flatbase bullets that Berger makes, as Andrew pointed out already. Those would be easier as FMJ. Steve. Steve, Jonathan, Allow me this one hypothesis. I have a SW 686S that also experiences leading, depending on what type of bullet I shoot. My thoughts are that in unjacketed bullets, the propensity for lead deposits is a matter of fact because of the way lead behaves under pressure, and due to the fact of its softness. Since metal in gun barrels -- especially rifled barrels is not anywhere near a glassy smooth surface, and because lead acts as its own lubricant (much as a brass bushing will act as a lubricant to a steel shaft in slow rpm devices), then lead will deposit to the companion surface it finds itself against - even hard alloy lead. The matter of soft lead is not so much the problem as the state that lead will find itself in the presence of heat. The softer the lead I believe, the greater the propensity for it to turn plastic on its outer molecular surface. If this is the case, then is would seem an easy matter to solve for by merely treating it with a conversion coating for its outer layer. I have no chemical in mind, but there possibly is something 'out there' that might work well. Lead doesn't have to melt to become a problem, merely soft enough to leave traces of it on the companion surfaces of the cylinder bore, and barrel, respectively. ET -- I'm not sure what causes it, but I'm convinced it happens. Perhaps the friction of the bullet against the barrel generates enough heat in the projectile that some of the lead at the base of the bullet vapourises, or perhaps it is as simple as the pressure built up pressing on the base of the bullet and knocking it out of shape. 9x25 Dillon was notorious for having problems with FMJ bullets. I can't believe it was simply the shooters imaginations. One of the main reasons 9x25 Dillon is so rarely used is because people can't afford to buy JHP bullets to load it with. I have heard some say this is all to do with the OAL length of cartridge, but Rob Leatham and Willy Peache both told me that FMJ bullets simply melted at the base. These guys between them probably shoot more ammo than everyone on this list put together, so I'm not going to simply ignore what they have told me. Who knows, maybe some idiot told them this and they believed it and simply repeated it! I will look into it a bit further as it was several years ago that I had these conversations. Steve. Cybershooters website: http://www.cybershooters.org List admin: [EMAIL PROTECTED] ___ T O P I C A The Email You Want. http://www.topica.com/t/16 Newsletters, Tips and Discussions on Your Favorite Topics
