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Discussion Starter #1
OK, let's assume a .45 using 230 gr with a maximum pressure load for that gun.

Now let's say we want to put in heavy bullet like 270 gr. Do you automatically get a lower FPS since you're already at maximum load with the 230?

One loading writer says you actually have to back off the load some and specifically says it's not just because of less case space.

Thanks a million

JimL
 

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That sounds right to me. If you are going to a heavier bullet then you would back off the powder charge.
The heavier the bullet the less powder charge you use.

Pulled these off of http://stevespages.com/451p_1.html
200 grain .45 ACP - AA-7 From 9.5 grains to 11.2 grains
230 grain .45 ACP - AA-7 From 8.6 grains to 10.7 grains
 

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Discussion Starter #3
Whirlwind06 said:
That sounds right to me. If you are going to a heavier bullet then you would back off the powder charge.
The heavier the bullet the less powder charge you use.
Care to comment on why? Would pushing the heavier bullet build the pressure beyond the already reached maximum? Some other reason?

Thanks a million

JimL
 

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Yeah it seems that way...


http://www.speer-bullets.com/default.asp?menu=1&s1=2&s2=25&pg=11
I have a light bullet (e.g. 125 grain) and the only load data I can locate is for a heavier bullet (e.g. 158 grain). I need a safe starting point to develop a load for this lighter bullet.
A.
The physics of loading cartridges indicates that a heavier bullet will build pressures faster than a lighter bullet owing to its mass. The greater mass of the heavier bullet resists change (acceleration) more than a lighter mass so the powder charges for the heavier bullet will nearly always be lower than those for the lighter bullet of the same construction. This indicates that, without other data to follow, the heavier bullet data can be used as a starting point for the lighter bullet.
http://www.reloadammo.com/relbulty.htm
The rule of thumb is always: when using a heavier bullet, use less powder for the same pressures. Heavier bullets makes the powder burn faster, as do jacketed bullets versus lead bullets. Faster burning creates greater pressures (and of course velocities).
 

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Go by your manuals!!!! Never just assume anything. Load from suggested loads in published manuals like the Speer manuals. A max load for a 230 grain bullet, same powder weight, put a 270 in front of it and, yes, you're going to be dangerously over pressure!

Never assume, never think for yourself, always go by the manuals. There's a reason you can't get loads in 270 grain for .45ACP. When loaded to max OAL, there'd be precious little powder space available in the case. For a load with that heavy a bullet, you need to move up to a .45 Colt revolver or something.

When you up the bullet weight, you have to drop off the powder charge for two reasons. First, the bullet is heavier, is going to spend more time in the case and bore on firing, and is going to build more peak pressure because of the length of time it's in the chamber/bore. Also, the reduced powder space.

Again, if you don't have a good manual like the speer manual, BUY ONE before handloading and READ it! You can get all the manuals from http://www.midwayusa.com

Specifically..... http://www.midwayusa.com/esearch.ex...+Begin+Search.x=13&Click+to+Begin+Search.y=10
 

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Discussion Starter #6
NativeTexan said:
Never assume, never think for yourself, always go by the manuals.
1. I never assume.

2. I always think for myself.

3. I'll probably never get a manual, because I have not and will probably never load a single round.

4. Why ask? This thread has answered by the back door a question that I couldn't get answered using a direct question.

Thanks a million

JimL
 

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Don't take it the wrong way. I figured you for a new reloader and safety is of primary concern in reloading.
 

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Why would one build a load like this if he could? Seems to me the benefit would be marginal at best and pressure would be dangerously high. Curious if anyone has attempted this? I agree to adhering to published specs,it's one reason I still have 10 fingers after all these years.
 

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Yep roscoe keeping those fingers does make it handy for other things. We had a guy in our reloading group that always had to load everything to the max or beyond. This was pistols, rifles, shotguns etc. He always complained his guns were not as accurate as ours, but would never listen to us or the books. One day he split the cylinder on his S&W .45 revolver in 3 parts, he just got a couple of minor cut to the hand. He stopped then, and his shooting got better. To the day that I last saw him he never admitted it was his fault, it was always that "crappy S&W gun.
True story, believe it or not.
 

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Discussion Starter #10
texas shooter said:
We had a guy in our reloading group that always had to load everything to the max or beyond. This was pistols, rifles, shotguns etc. He always complained his guns were not as accurate as ours, but would never listen to us or the books. One day he split the cylinder on his S&W .45 revolver in 3 parts, he just got a couple of minor cut to the hand. He stopped then, and his shooting got better. To the day that I last saw him he never admitted it was his fault, it was always that "crappy S&W gun.
True story, believe it or not.
Hm. Gees, I may not be a loader, but I'm not just plain stupid. Why pay good money for the books and ignore them?

JimL
 

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The old axiom is, if you want a .357 Magnum, buy one. Don't try to make it out of a .38 special. However, I do hot rod my .45 Colt hunting loads out of my Contender or my Ruger Blackhawk. There are special loads only for guns this strong in the manuals. You could fire one of these out of a Raging Bull, but not your Tracker in .45 Colt. These rounds involve a 300 grain XTP at around 1200 fps (can go up to 1300 fps in some manuals). They will do anything a .44 magnum will do and the reason I like the old Colt is that Blackhawks are handier than Super Blackhawks. Of course, a S&W mountain gun in .44 mag can do a lot more than the same gun in .45 colt which is too weak for Ruger/TC loads. So, I guess, with the Colt, it just depends on the gun whether you're better off shooting it or switching to .44 mag.

Normally, though, if you need to hot rod your gun, you probably need to step up to a more powerful gun. Auto loaders and especially 1911s cannot handle hotrodding as well as revolvers, either, due to their cycling dynamics. Oh, you can put a stiffer spring in it, a recoil buffer, but it's still going to be hard on the gun. This is why the 10mm is out of favor and there aren't really many magnum level loads other than 10mm for autos that are of reasonable size and of delay blow back rather than gas operation. You can get in real trouble trying to hot rod an auto loader round.
 

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Discussion Starter #12
NativeTexan said:
Normally, though, if you need to hot rod your gun,
I read a magazine article about using heavier bullets and didn't really "get" the mechanics - still don't.

NOTE: (My questions still have nothing to do with ME reloading, since I don't and won't. I'm just trying to wrap my mind around some concepts.)

Aside from book rules and all, purely theoretically:

1. Would putting a "heavy" bullet on a "medium bullet" load be what you would call hot rodding your gun, since it increases pressures?

2. Would putting a "light" bullet on that same "medium bullet" load be making it easier on the gun?

JimL
 

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You work up to a maximum pressure for any bullet weight which is mandated by SAAMI (small arms ammunition manufactures institute, or something such, and organization of ammunition manufacturers that sets the standards) . Any bullet weight will be loaded to within SAAMI working pressure for the caliber. If you load a lighter bullet to a heavier bullet's charge weight, you will get less pressure. If you seat a heavier bullet over the lighter bullet's maximum charge weight, you could be dangerously over pressure. Overall length, or the amount of bullet seating also affects pressure as well as do other variables.

By "hot rodding", I mean exceeding maximum working pressure for a caliber. In the case of my .45 Colt loads in the Blackhawk, SAAMI has set NEW pressure standards for "+P" loadings of the old .45 Colt. Maximum working pressure for the old colt round in weaker guns is 15,900 copper units of pressure (CUP). The Speer No 11 manual lists a maximum pressure of 25,000 CUP for their Ruger/Contender only loads. This makes about 300 fps difference in velocity with a given bullet weight. This is what I'd call "hot rodding". Has less to do with bullet weight as to cartridge working pressure.

There's books, volumes of books written about this stuff. You could probably benefit by some reading. Interior ballistics, what goes on inside the gun on firing, is pretty complicated compared to exterior (flight of the bullet) and even terminal (effects of the bullet on flesh) ballistics. The mathematics of exterior ballistics is well known and pretty straight forward and is what we, as handloaders, tend to concentrate on. But, while interior ballistics is quite a bit more complicated, a good a basic knowledge of it is far more important to the handloader just from the standpoint of safety. Basic rule, though, don't argue with the manuals.
 

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Discussion Starter #14
NativeTexan said:
don't argue with the manuals.
I see I still haven't made my point about theorizing about what's going on as opposed to real loading.

I certainly get your point - and all the other re-loaders who've told me to follow the book. You sit down at a loading bench and follow rules. That's how you think. I sit down at a bowl of raisin bran and follow concepts. That's how I think. (When I was young and brilliant I sat under an apple tree and a branch fell on my head.) :)

JimL
 

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If what your asking is that do heavier bullets take less powder, they do. Take a .40 s&w gold dot bullet load. A 165gr max load with power pistol is 7.8gr for 1081fps. A 180gr is 7.2 for 1013fps.
 

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JimL, If you read almost any reloading manual they will state if you change one component of the described load you need to back off & start with a lower powder charge. Even different brands of the same weight bullet can give different pressure. Different primers can too. I'd suggest purchasing a couple of good loading manuals, & read them thoroughly to get started on a safe career of reloading. Done correctly, reloading is satisifying,safe,cheaper than factory, & you can tailor a load for a specific gun. Good Shooting. Frank
 

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i'm not sure you guys are understanding the context of his question. i think what he's wanting is some basic theory of how a bullet is shot through the barrel. it's not a matter of reloading manuals.

the reaction of the gun powder is more of a gradual push than an instantaneous hit when the primer is hit. well, it's 'gradual' if one were comparing flame propogation to the speed of light.

when the primer flashes, the flame front moves to the gun powder, causing it to oxidize very rapidly. this reaction is also exothermic (it gives off heat). i've read that for each mole of gunpowder, it's converted into something like 200 moles of gas, which creates the pressure rise pushing the bullet (someone with more off-top-of-head knowledge should correct if my number is wrong).

anyway, it's really inertia of the bullet that regulates the maximum pressure (which is related to weight, or mass more precisely - pushing a bullet on the moon should take the same amount of energy as pushing a bullet on earth (horizontally, really. the force of acceleration due to gravity applies more to the external ballistics). as the gun powder oxidizes, the bullet meets resistance of the rifling as well, and this along with the inertia of the bullet 'backs-up' the oxidation of the powder. the powder burn is instant if compared to the reaction of the bullet (an object at rest wants to stay at rest...)

now, the maximum pressure of a gun powder load depends on a meriad of variables. one is mass. adding mass to the bullet increases its inertia (the force due to resistance of the rifling should be consistant with the same barrel), thus increasing the 'back-up' of the power burn. this increases the maximum pressure, and can lead to devestating effects (which is why the reloaders on this site strongly urge against it, and rightly so).

another is burn speed. if a powder oxidizes faster, it will reach maximum pressure quicker, and since there is a smaller volume behind the bullet to contain the burn, it can also lead to dangerous side effects. a higher mass bullet on top of a fast powder would be even more disastorous. with slower burning powders, such as the .45 acp, the pressure is built up gradually, ideally taking the entire barrel length to build up maximum pressure.

it's a balance between burn speed and maximum pressure. the ideal load would use a powder that will a: have all of it's powder oxidized, and thus turned into gas, and b: reach maximum pressure just as the bullet leaves the muzzle. this makes sure that all the available powder has converted to gas to add pressure, and that the bullet doesn't slow down due to rifling/etc. drag after the gas reaches maximum pressure.

so, if you add bullet mass, the same powder load for a lighter bullet will result in a higher maximum pressure and thus is ill-advised. backing down the powder charge keeps the pressure at or below saami pressures. this also results in a slower muzzle velocity, since the energy transfer must be constant. because the pressures are the same, the two powder weights *should* apply the same amount of kinetic energy to both bullets, so m*v^2 of one bullet should be equal to m*v^2 of the other bullet. if you increase m of one side, v of the other side (or the square of v) should decrease the same amount.

now, this is by no means the end-all, be-all of internal ballistics. i'm just summarizing some of what i have picked up along the way. if somebody with more experience in the physics/chemistry, please chime in.
 

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All the information so far is a good idea to consider but you need to load ammunition with two points in mind.

You cant reload to a preconcieved idea of how strong your gun is. THe maker puts a safety margin into the cylinder as far as how much pressure it can contain. Sure you should hopefully get bulged primers long before you get to your cylinders danger zone.
But you can never be sure of what that safety level is, so just about all smart proffessional relaoders that i have read about all encourage reloaders to load with a safety zone.

Normally they will reload a cartridge that has a SAAMI standard of 35,000psi to 32-33,000 psi just to make sure that if a little variation occurs in the cartridge some how, there firearm and THEM have a good high rate of NO BOOM BOOM happening.

As for huge bullets in a given pressure limit, i would make a phone call to Buffalo Bore, theyve done a huge amount of testing various loads and handguns to make their loads "safe" as they can. Hence id ask them as theyve already done what you want to do.
 
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