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Discussion Starter #1
Alliant's Reloaders Guide warns
"DO NOT EXCEED THE LOADS DISPLAYED ON THE SITE OR ALLIANT'S RELOADERS GUIDE"

Alliant's load data for Unique in .357Mag shows two charges for 158 grain bullets:

6 gr @ Speer LSWC, CCI 500, Min OAL 1.57
7.7 gr @ Speer GDHP, CCI 500, Min OAL 1.575

I can't imagine that chamber pressure cares whether you're loading a gold dot or a SWC, so how might I interpret these data to suggest a safe max charge for Unique in 357Mag with a 158 grain bullet?
 

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first one is for lead bullets second is for jacketed. the lead can only be pushed so fast without a gas check and not lead to sevre leading of the barrel. not a problem with jacketed.
 

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You can load the lead bullrts to the higher velocity. The tables usually show the hottest load for lead, that you can shoot without leading the barrel. If you use a harder lead compound, like a linotype mixture, or use lead bullets with gas checks, you can load to the higher velocity without danger of leading. I have some 38 special loads using bullets made of pure lead, for serious social work. Yes, they will lead the barrel, but, they will damn sure expand upon contact, and I can clean the gun later. Conversely, I have some .357 mag, and .44 mag loads using bullets cast out of pure linotype, with gas checks, that do not expand, even if shot into sand. These are for tough sinuous creatures, like wild hogs......Robin
 

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Two completely different bullets! Lead has a lower friction coeffecient so it takes less pressure to drive a bullet through the barrel. Jacketed bullets are generally smaller (.001"-.002") but rerquire higher pressure because of higher friction (it needs more powder to achieve velocities). Stick to the book data until you get the "whys and wherefores" of reloading down pat. Barrel leading is a whole different story...
 

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Alliant's Reloaders Guide warns
"DO NOT EXCEED THE LOADS DISPLAYED ON THE SITE OR ALLIANT'S RELOADERS GUIDE"

Alliant's load data for Unique in .357Mag shows two charges for 158 grain bullets:

6 gr @ Speer LSWC, CCI 500, Min OAL 1.57
7.7 gr @ Speer GDHP, CCI 500, Min OAL 1.575

I can't imagine that chamber pressure cares whether you're loading a gold dot or a SWC, so how might I interpret these data to suggest a safe max charge for Unique in 357Mag with a 158 grain bullet?
Might be a thought to not go right to the published data sites until after reading a couple of reloading manuals so that the differences in bullet descriptive abbreviations are clear to you...the L prefix on the SWC is "lead"..and as said, whole different critter than the Speer Jacketed Hollow point....Not kicking you around but want to help you be safe...I've "shortcutted things" all my life...still guilty of it now and again but with the reloading every tenth of a grain, every foot per second and every abbreviation makes it unique to that load only...even primer and brass manufacturers and test barrel length can make a difference...be safe and enjoy the hobby.
 

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Learn the signs of excessive pressure. Work up loads in your gun(s) until you begin to see signs of excessive pressure, then back off your powder charge 10% or more. This would be a "safe" maximum load in your gun(s). I pay little attention to the warnings like you have quoted. They are there for the powder manufacturers own protection and on the lower end of the scale because they don't have any idea what guns, or its condition, a particular load may be used in. The same is true for off the shelf ammo. It is generally lower power than many guns can use...simply because they have no idea what guns it will be used in. They make it sound as though it is for the consumers protection, and maybe it is partly, but it really is for their own protection. They don't want to be sued every time a gun blows up.

I know this may raise some eyebrows, but the great part of reloading is that you can tailor loads for your particular firearm.

Of course this only applies to those who take the time to know the pressure signs and are well versed (and properly equipped) in reloading.
 

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Discussion Starter #7 (Edited)
.... Not kicking you around ...
The thought didn't occur to me.

I am aware that the LSWC is a cast lead bullet.

My interest is in understanding how to define a maximum safe charge for Unique with a 158 gr bullet (that is, ANY 158 gr bullet) in a .357Mag using factory/manufacturer load data. I don't want to load to that number, I would just like to have it as a point of reference so that a typo or malicious post doesn't bite me.

For example, in the Unique data the 158 gr loads are 6.0 and 7.7. When charges are specified to 0.1 grains, that's a big delta.

Leading is a sanitation concern, not a safety problem. Granted, poor sanitation can lead to a safety problem, but I do clean my guns.

The internet is rife with pictures of blown up revolvers. Revolvers that blow up due to barrel obstructions yield photos of blown up barrels. Revolvers that blow up from double charging or overcharging yield photos of blown cylinders and bent top straps. This suggests to me that the uh-oh of overcharging occurs in the cylinder and cylinder throat, areas of more generous diameters that should mitigate bullet friction/sizing differences.

HAWKEN's post noting that the 6.0 for LSWC and 7.7 for jacketed is a nod to leading prevention makes sense and also suggests that the Alliant data best suited to my interest would be the gold dot data.
 

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mikld, I love these "gun myths" because they are always based on a little bit of fact and a whole lot of fiction. Yes indeed, lead bullets do generate higher velocities than jacketed bullets, assuming the same powder charge and bullet weight and yes indeed, lead bullets have less bore friction than jacketed bullets .... but that has nothing to do with the reason. The reason is quite simple .... lead bullets seal much better in the bore and do not lose pressure from gaps between the bore and bullets like jacketed bullets do.

It turns out ... bore friction has the opposite effect than what you might think. Here's a good scenario .... let's use a 223 Rem rifle with the same factory ammo for two different tests. The first test uses moly dry lubricant coating on the bullets that reduces bore friction considerably. The second test uses the same exact ammo but with no moly. Which bullet will chronograph the fastest? One would think the moly coated bullet should be faster because there is less bore friction. Not true! The moly coated bullet will chronograph about 100 fps slower than the non-moly coated bullet and here's why. More friction causes more pressure to build. More pressure drives the bullet faster. If it weren't for the fact that lead bullets seal better and don't waste as much pressure, in theory a jacketed bullet with more bore friction would generate higher velocities. Sounds backwards but it is true.

pell, When lead bullet loads are listed in reloading manuals, they are not the maximim pressure powder charges, rather they are the optimum charge weight to produce foul free bores. Lead bore fouling is a lot more than a sanitary condition because it directly affects accuracy. As lead fouling builds up, accuracy continues to get worse. Here a document I put in the Library that might help explain the situation better. Click on this link: http://rugerforum.net/library/19869-lead-bullets-revolvers.html

A few words of wisdom ... Unique is not a good powder for 357 Mags if you want full magnum velocity. It burns too fast and generates too much initial pressure then peters out in a few inches of bullet travel. Slow burning powder such as H-110 will generate magnum velocities and won't develop near as much chamber pressure.

To answer your question .... there isn't one specific Unique powder charge that would be the maximum pressure for all 158 gr bullets. The reason is ... the bullet profile and seating depth is different with different brands/types of bullets and that has a dramatic effect on chamber pressure. The best advice I can give is to buy a reputable reloading manual such as Speer #14 or Hornady 7th Edition and use the data verbatim. You will never exceed SAAMI max pressures with "book loads" from either of these sources. When you start playing "mix-n-match" ... a bullet from one manufacturer and data from another, you can get yourself in big trouble.
 

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Discussion Starter #9
Thanks to all for taking the time to read and respond. I do appreciate the information and the experience that it represents.
 

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mikld, I love these "gun myths" because they are always based on a little bit of fact and a whole lot of fiction. Yes indeed, lead bullets do generate higher velocities than jacketed bullets, assuming the same powder charge and bullet weight and yes indeed, lead bullets have less bore friction than jacketed bullets .... but that has nothing to do with the reason. The reason is quite simple .... lead bullets seal much better in the bore and do not lose pressure from gaps between the bore and bullets like jacketed bullets do.

It turns out ... bore friction has the opposite effect than what you might think. Here's a good scenario .... let's use a 223 Rem rifle with the same factory ammo for two different tests. The first test uses moly dry lubricant coating on the bullets that reduces bore friction considerably. The second test uses the same exact ammo but with no moly. Which bullet will chronograph the fastest? One would think the moly coated bullet should be faster because there is less bore friction. Not true! The moly coated bullet will chronograph about 100 fps slower than the non-moly coated bullet and here's why. More friction causes more pressure to build. More pressure drives the bullet faster. If it weren't for the fact that lead bullets seal better and don't waste as much pressure, in theory a jacketed bullet with more bore friction would generate higher velocities. Sounds backwards but it is true.

pell, When lead bullet loads are listed in reloading manuals, they are not the maximim pressure powder charges, rather they are the optimum charge weight to produce foul free bores. Lead bore fouling is a lot more than a sanitary condition because it directly affects accuracy. As lead fouling builds up, accuracy continues to get worse. Here a document I put in the Library that might help explain the situation better. Click on this link: http://rugerforum.net/library/19869-lead-bullets-revolvers.html

A few words of wisdom ... Unique is not a good powder for 357 Mags if you want full magnum velocity. It burns too fast and generates too much initial pressure then peters out in a few inches of bullet travel. Slow burning powder such as H-110 will generate magnum velocities and won't develop near as much chamber pressure.

To answer your question .... there isn't one specific Unique powder charge that would be the maximum pressure for all 158 gr bullets. The reason is ... the bullet profile and seating depth is different with different brands/types of bullets and that has a dramatic effect on chamber pressure. The best advice I can give is to buy a reputable reloading manual such as Speer #14 or Hornady 7th Edition and use the data verbatim. You will never exceed SAAMI max pressures with "book loads" from either of these sources. When you start playing "mix-n-match" ... a bullet from one manufacturer and data from another, you can get yourself in big trouble.
When I answer a beginner's question, I try to keep my answers simple as possible. Lead bullets require less powder to achieve the same velocity as a jacket bullet. I think the friction factor is easier to explain/understand than bullet hardness/obituration/lube sealing. That's what I was trying to say, but I just missed it.
 

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Plus lead has to be shot slower than jacketed.
That just isn't true ... at least at handgun velocities. I've been up 1333fps with no leading (no more than normal that is) and no gas checks in .44Mag... Match hardness to velocity I think is key to allow the bullet to obturate properly and not slip in the rifling.... Of course bullet size, throat size, barrel constrictions all enter into the 'leading' question which is a topic all its own... Defer to Iowegan for final word, but from my experience (I only shoot lead ...)
 

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That just isn't true ... at least at handgun velocities. I've been up 1333fps with no leading (no more than normal that is) and no gas checks in .44Mag... Match hardness to velocity I think is key to allow the bullet to obturate properly and not slip in the rifling.... Of course bullet size, throat size, barrel constrictions all enter into the 'leading' question which is a topic all its own... Defer to Iowegan for final word, but from my experience (I only shoot lead ...)
I like and use extruded lead bullets. Speer makes really good extruded lead bullets. So does Remington. You would never damage a gun with 6gr of Unique under one, but I find that even 6gr will lead foul the bores of my .357's pretty quick.

Really good casters can whip up an alloy that will sustain 1300fps, and really lucky shooters can purchase a supply of cast from supplier "X" that can handle those numbers from their handguns. I have never been so lucky with my Rugers. My new SP101 shows promise, but I'll never know as I feel 900-1000fps from my SP101 to be totally fine.
 

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mikld, No problem .... Yes, easier to explain but not as factual. No malice intended.

Buffalo11, I'm not sure what you mean:
6" bbl vs. 10"bbl?
but I'll take a stab at it, dispel another common "gun myth", and yes, I think you are missing something here.

Barrel length has very little to do with bore fouling. Once the bullet has been sized by the forcing cone, engraved by the rifling, and has traveled an inch or so down the bore, it will literally coast the rest of the way down the bore with way less friction than it started with. Of course there is still considerable pressure pushing the bullet so it will continue to increase in velocity until the bullet exits the muzzle.

Lead fouling in the bore comes from a couple sources. If the bullet is too small to get a good seal, hot expanding pressure will "blow by" the bullet and melt a little lead off the circumference. This turns to lead vapor where most of it is blown out of the muzzle but some stays in the bore, cools off, and turns to solid lead fouling. The bullet may either start off too small or it may be sized down by tight cylinder throats ... either condition will result in bore fouling. The optimum lead bullet will be delivered to the forcing cone .001" larger than bore diameter ... not so fat where lead is shaved off and not so skinny where the bullet fails to get a good seal.

If lead bullets are the proper hardness, they will expand slightly (obturate) to maintain a good bore seal from the forcing cone all the way to the muzzle. Bullet hardness must be matched to chamber pressure or they will foul badly whether they are too hard or too soft. The formula is: chamber pressure divided by 1400 = bullet hardness rated in BHN. Example: a 45 Colt develops 14,000 psi of chamber pressure. 14,000/1400=10. A bullet with a hardness of BHN 10 will match chamber pressure just about perfect and will not foul the bore (assuming the bullet diameter is .452", cylinder throats are sized properly at .4525", and the bore is not rough). With lead bullets, accuracy always goes hand-in-hand with bore fouling ... the more lead fouling that builds up, the worse accuracy gets.

I have successfully run revolver velocities as high as 1500 fps with lead bullets ... very accurate loads without a hint of lead fouling. Of course I had to do my homework and figure out the chamber pressure then find a bullet with the right hardness. Another example is a 22 LR rifle. 22 LR bullets are typically very soft ... about BHN 5 and with normal high velocity ammo, the standard muzzle velocity is 1255 fps from a 24" barrel. Hyper velocity 22s can run up to 1600 fps (CCI Stingers) but have slightly harder bullets (BHN 8). These bullets match chamber pressure quite well and won't foul a decent 24" barrel. Of course if you have a rough bore ... all bets are off.

Fact is, with most revolver loads, you can run lead bullets just as fast as jacketed bullets. The reason why most people don't have much success with high velocity lead bullet loads is because they don't know about matching bullet hardness to chamber pressure. It works ... first time and every time.

Again, I would invite you to take a look at the Library document as noted in my above post. It explains all this stuff in detail.
 

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TMan51, I think you mean "swaged" ... never heard of "extruded" but that may well be an accurate term. Swaged bullets are not cast. They start out as a lead "wire" then are cut to length for the proper weight. The chunk of lead wire is put into a die then pressed into shape by a big punch press. The advantages of swaged bullets are ..... they are very uniform weight, have no casting marks or spues, and are much softer than most cast bullets ... typically BHN 8~10 but can be as soft as BHN 5 or as hard as BHN 12. The swaging process only works well with soft lead. Typical applications are: hollow base wad cutters, 38 Cal, 44 Cal, and 45 Cal bullets for lower pressure loads.
 

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I would like to add that you don't have to match up 'exactly'. That would be impossible for most of us. Just find a bullet that is close to what you will be shooting. For example, I use bullets that are said to be around 15 BHN. I've found they work well for most all the velocities I want to shoot whether .357, .44Mag to .45 Colt . Just so the bullets aren't to soft, or way to hard....
 

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TMan51, I think you mean "swaged" ....
How about swaged from extruded lead wire? :):)

I visited the Speer plant many years ago while on a bow hunt. The operator on the swaged line referred to the bullets as extruded when he explained the process. It stuck in my tiny brain to this day.

I like them though. They are great for reduced loads, where the harder cast stuff works not so well.
 

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TMan51, I'll buy that!
 
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