Given that both are loaded to the same pressure, then the light bullet load would give more flame cutting/barrel erosion. think of peak pressure as the temperature, and the amount of powder uses as the time. Light bullets use more powder at that peak pressure, so they erode the barrel a bit faster.
Lot of early .357max.'s showed serious erosion pretty quickly....the ones used to toss 180-200gr. bullets at the same pressure lasted longer.
Recoil has some effect on gun wear as well, moslty giving end shake to revolvers and slide batterning to semi-autos, but of the two types of wear (recoil induced / flame induced) the erosion is a more serious peoblem.
BY SHOOTING THE SLOWER POWDERS, USUALLY WINCHESTERS 296 AND HODGDONS H110, JOHN LINEBAUGH HAS OBSERVED ON HIS WEBSITE THAT THE GUNS STAY TIGHT AND LAST LONGER THAN SHOOTING FASTER POWDERS (AND LIGHTER BULLETS?).
THE THEORY IS THAT THE FASTER POWDERS 'HIT THE GUN' FASTER AND INDUCE MORE WEAR AND TEAR ON THE FRAME. THE SLOWER POWDERS, ESPECIALLY 2400 AND 4227, ALSO ARE REPUTED TO CAUSE LESS BORE EROSION.
IT'S MORE COMPLICATED THAN ALL THIS ANYWAY. THE USE OF CAST, OR HARD-CAST BULLETS WILL REDUCE WEAR ON THE BARREL. THAT IS ONE ASPECT IN DURABILITY, TOO.
I DON'T HOLD WITH LINEBAUGH'S 45 LONG COLT THESIS, BECAUSE HE DOESN'T SPEAK TO THE VARIATIONS IN SOME OF HIS TEST RESULTS AS I'D EXPECTED. (THE USE OF GAS CHECKS VS. PLAIN-BASE BULLETS IS A FACTOR. THE STANDARD DEVIATION IN VELOCITIES WAS NOT GOOD WITH THE 45 LONG COLT, ETC.ETC.) BUT I CAN'T SEE MUCH ARGUMENT WITH HIS GRASP OF FIREARM LONGEVITY. IT MAKES SENSE TO ME.
LINEBAUGH'S SITE CAN BE REACHED VIA: SIXGUNNER.COM.
Now Mr. Linebaugh isn't one for "squib" loads and his belief in slower powders may be right..but his experiences aren't quie the same as the average handgunner loaign up this .357 for range use. If you load light bullets and heavy bullets to the same pressure using the same powder, you end up using a lot more of that slow powder with the light bullets, so believe the wear factor would be greater with the light bullets.
If you used fast powders, think the erosion would be more for both weights of bullets, but the light ones would still lead the heavy ones.
Don't think the heavy vs. light difference inwear is all that much...believe that the pressue level used has more to do with it. Better to use cast bullets at less that cylinder busting pressure if you desire a long lived barrel.
Personally, I don't worry about it. IF a gun is used, it will wear. It takes a good bit of shooting to erode a forcing cone, and getting a new barrel or having the old one set back and refaced is just part of the rebulid price if you are lucky enough to shoot that often. By tht time that needs to be done, the timing will be off and there will be some end shake to take care of (in revolvers).
To further elaborate - I have recently acquired a Colt Peacemaker clone - AWA Peacekeeper. These guns are not designed for high pressures to begin with and my intentions for it are purely pleasure shooting. Cast bullets are all I will be shooting in it.
The situation I have is that my current .45 moulds are 300gr and 315gr respectively - nice for the Rugers and Casull but I'm concerned about wear and tear on the lighter gun. My thoughts are to keep this loaded down to BP equivalent pressures or slightly less. I'm not sure if the slower burning numbers (on the order of 2400) are suitable here or not. My estimates suggest that I'll probably be needing to hold velocity down to the 700fps-750fps range top end if using the heavier bullets, and powder selection will likely be one of the medium fast numbers either side of Unique as a reference point..
Any additional thoughts based on the specific application?
Have to agree,,,it will shoot high. Easiest to see on a short barreled big bore revolver, but when the sights are aligned to the target, the barrel is actually pointing UNDER the target. With a straight edge, can show this angulation with the average 2" .38specail...can SEE it in the old 3" .44 charter arms real well. Idea is that as the bullet starts forward, recoil starts...the barrel rotates as the bullet is accelerated through, and at the time of exit, the barrel has rotated in line with the target (or a bit above to allow for long range drop).
Now...given nearly the same speed, at short range it's common for lighter bullets to shoot lower. IF keeping the same weight, can drive it a bit faster...I know that increases total recoil, but it seems to decrease the bullet-in'the-barrel (barrel time) rotation. You don't get that last choice at the pressure levels you need to work within.
Wouldn't think that a .22 would show this, but in an Airlight S&W, that Aguila 60gr. load prints 3" higher than the light Singer load at 15yards. In miniature, that translates to a slower but heavier bullet...so more barrel time...so more "flip" before exit.
That 300gr. bullet at those lower speeds with have a long barrel time, and more rotation (recoil if you like) occurs before bullet exit...would guess that bullet may be as much as 6 to8" high at 25yards (and may be more).
No one whats to weld on a new expsnisve revolver, but there isn't a good way to get new steel to grow on top of a sight. May end up using ligher bullets just to keep POA and POI close together.
My target is to run these bullets out in the 700-750fps range. All the loads except for the SR 7625 fell shy of the target - IN THIS GUN.
An interesting side note - prior to squeezing off these rounds - I shot 1 ea through my Ruger Blackhawk to be sure that I would not be running too hot compared to my estimates. In each case - the velocities out of the blackhawk are running 100-150fps faster - bbl length is only 3/4" longer!!!
Regarding the point of impact - this is a fresh out of the box new gun and so the front sight has not been adjusted for loads yet. As such - it is printing considerably low from point of aim which is fine - it'll need to be filed down to bring point of impact up once I selttle on a load. Finding the right load will take some more time as none of these today really showed me much. With the difference in velocity vs. the Blackhawk - I think I need to slug the cylinders and bore to see if I'm sized correctly or not.
Why even really worry about it? Find the best load you can shoot from the gun and have fun. Eventually every gun will wear out anyways. Heavy bullets require less poweder therefore less flash and burn. Typically I shoot the heaviest bullets I can out of all my guns with the exception of those I choose to shoot for beer. 168g .308 is not the heaviest .308 but it shoots the smallest groups.
The difference in velocity you are experiencing with the Colt clone and the Blackhawk can be to do with more than just the throats. The barrel/cylinder gap would be the first thing. The angle and length of the forcing cone can also have some effect. The commonly undersized throats on the Ruger can be a problem, but I would think it would be a drop in velocity.
Are you getting leading? The alloy you mentioned is not overly hard, but these pressures are also quite low. The bullet may not be obturating in the throat and/or the bore.
Thanks for your comments. I'll have to get out the feeler gauges to compare bbl/cylinder gap.
Regarding alloy hardness. Correct - mine is not overly hard. I have found that for velocities thru 1800fps (GC bullets in rifles) - this 12.5BHN alloy works very well without leading. Never a leading problem with my revolver loads running 1200-1300fps with PB bullets either. In fact - the only leading problems I ever experienced personally in my revolvers was from using bullets that were very hard (BHN 19) at mild velocity in my .44 (1000fps). That was before I had learned anything about bullet fit and I suspect that the bullets were undersize.
Anyhow - another update for those interested. I asked the same question (regarding heavy vs. light bullets) of Mr. Bowen of Bowen Classic Arms. His reply is interesting in it's contrast to others. He noted 2 key issues... 1) Peak pressure is not the only factor - but the duration over which the pressure exists. 2) Heavier bullets produce more recoil which will take it's toll on fit of pins etc. He also commented that for any Colt or clone - he would never personally select 300+gr bullets.
What Bowen said makes sense. The heavier bullet light loads produce more energy than the light bullet light loads that are common in the revolver. I would imagine the dispersal of energy from the revolver is what causes the wear. I'll agree that certain types of powders will affect wear in the cylinder/barrel/throat area. That is a different type of wear than Bowen is talking about though. He's talking structural wear,"tightness",and it makes sense. Let me know what you find in your barre/cylinder gap measurements. It pays to perform this test with all 6, or 5, holes in the cylinder behind the barrel. You'll get a better reading and also see if there are any possible mechanical problems with your revolver that may be causing less than ideal accuracy.
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