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Thread: Reloading high velocity for the .357 Magnum

  1. #1
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    Hi ya-all,

    Its me again. The guy that doesn't know how to properly paragraph, and has other problems with his manner of posting. But I'm going to try and improve in this area with a little help from my friends on this site, thanks!

    Anyway, I have been loading for my .357 revolvers for a long time, and of course, as you are all aware, I like high velocity and accuracy to mix with that. It is no secret that the .357 mag. is capable of producing some of the highest velocity handgun loads one can possibly imagine. FYI, I wouldn't personally load these type of loads in an average quality revolver. I shoot them through S&W 66-5, Taurus 608, Ruger GP100, Ruger SP101 and have had absolutely zero ill effects other than a sore wrist.

    One of my favorite loads is with a Hornady 125 Grain XTPHP with a 20.5 grain load of H-110 or if I can't find that powder than I'll use W-296 with a similar charge, 20.6 gr.

    I've have gotten a lot of remarks about my high pressure loads over the years ranging from stuff like," that load will never be accurate", "the pressures are too high to be safe", and "what do you need that kind of velocity for?".

    In truth I guess those are all good arguments, but not exactly accurate. I've shot myrevolvers from a good rest at 20 yds. with these loads and have grouped consistently tight groups that would be considered as good as it gets with any load.A lot of super high velocity loads do suffer accuracy issues, but I think it has a lot to do with how the load is assembled. Seating depth is of great importance, powder choice unquestionably important, and bullet choice must be matched to the gun being utilized.

    For my S&W I seat the bullet to 1.585" in a case trimmed to 1.290", no shorter, and no more than .002" longer as this case length is already at maximum length. For some reason if I trim any shorter than that I start to get jumping velocities that range from 1880s fps to 2160s. I haven't yet figured out the reason for this, but I suspect it has something to do with high pressure blowing back from the rear of the barrel prior to the bullet entering the lands. This might be due to free space allowing the high pressures to escape past the bullet before it enters the bearing surface of the cylinder and then of course blowing straight back to the front of the bullet. I'm also suspicious of this causing the bullet to possibly canter before contacting the lands, thus effecting accuracy as well. But when I follow the procedure for this revolver to the letter my velocity only varies +/- about 15 or 20 fps, with the average being 2122 fps.

    With my Taurus its a whole different story. This revolver doesn't really have a bearing surface at the front of the cylinder to speak of. What would be thebearing surface is measuring .35755", which isn't containing much pressure during the free space travel. My S&W is supertight measuring .35690" providing a tight fit. But strange as well, is that I'm not getting the reversed pressures blowing back into the bullet prior to contacting the lands with the Taurus. Accuracy is superb as well with these high velocity loads in both revolvers. Both of these revolvers have around 2 1/2" barrels, with the Taurus having a recoil compensator.With the Taurus my brass is performing best when trimmed to 1.280" with a seating depth of 1.590". Velocity is always consistent with this revolver with less than +/- 20 fps variation, and the average being 2087 fps. I think my average is downcompared tothe S&W for two reasons. One, the cylinder bearing surface is tighter on the S&W, and two, the Taurus is compensated which might be causing some reverse pressures blowing back at the end of the barrel.
    I haven't finished developing the loads for the other 2 revolvers yet, but I'm expecting to find they will be a totally different animal to load for compared to the S&W and the Taurus. Initially I'm discovering the two Rugers are seemingly less picky. But I'll start getting serious some time this weekend and see what happens.

    When seconds count, the police are only minutes away!

  2. #2
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    Typically the terms "Highest Velocity" And "Most Accurate" are not used in the same sentence.

    Your goal should be consistent accuracy, withthe most consistent velocity between rounds using the same data.

    Consistent velocities are a good sign that you are nearing the best accuracy you can expect from a certainround, or the gun it is being fired from. Why does it make a difference to you if it is traveling 20 FPS faster or slower than another set of load data? Are you trying to set a velocity record or something?

    Lets look at it this way, you're shooting a revolver, you alreadyhave the ability to load more accurate rounds than youor the gun is capable of firing. Higher velocities mean nothing when it comes to accuracy. Especially if you plan to shoot the same round out of several different guns.
    You need to load specifically to each and every gun, and use those loads in the specific guns you created them for if you want the utmost in accuracy.

    My suggestion would be to back down on your loads to get better accuracy, save powder, and to quit putting your gun under all the extra stresses of these uber hot loads you have been making.

    I custom load my ammo, but just for my rifles. I use fire-formed brass, yes I have achieved velocities that have spun the jacket off and watched a grey streak of dust from the bullet coming apart while it was going downrange before seeing any signs of over-pressuring. But what does that accomplish? Nothing but higher stresses on the gun and myself.
    I found my best accuracy withloads at the lower end of the data,

    For my pistols and revolver, I use load data that produces the best accuracy and function of the firearm. And I have also found that to be very near the starting load data.

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    Yep I second what Nutczac says about high velocity and accuracy. I pop off about 3000 357mag a year target shooting at 25m and lower velocities are far more accurate. My current load is 6.2grn of bullseye with fmj 158 rnfp bullets. I cant shoot pistols here in the UK so I'm using a Rossi Puma with a 14" barrel (dont think you are allowed that one in much ofUSA).

    Think about it, .22 pistol shooters in the olympics used to use .22 short because it was more accurate that .22lr (not readily available now hence the change). Some of the reasoning was less shock to move the wrist and keeping poa.

    But then againwe select ammo to suit the gun so perhaps yours suits higher velocity stuff.

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    First of all, thanks for the reply,

    I want to address the variation in velocities, I stated only 15 to 20 fps variation. This is very acceptable to me and is what I'mhappy to achieve. But very much a normal variation with loads that are carefully weighed. And second, I can't argue with you about lower velocity loads often being the more accurate of loads, just not with slow burning powders because the data does not allow for that. What I'm doing is startingat the lower end of the data using a slow burning powder, and then working up to the point that I'm achieving accuracy, and magnum velocity. I'm doing that and have loaded like that for over 2 decades and have yet to wear a revolver out or burn a barrel.

    Often the data will show the most accurate load to be one that uses a slow burning powder, which is also in the higher velocity range, unless referring to non jacketed bullet with fast burning powders, which is where we seem to disagree. We load in two different worlds and will never agree on my concept, or me, on your concept. Enjoy what you do, as I will what I do, and know that I always appreciate a good debate without taking it personal, as I would hopeto be your reaction.

    I'm a different type of re-loader in several different manners. First, I never load with anything but slow burning powders, and I'll elaborate on that more in a moment. Second, I own and shoot high quality magnum revolvers, so as to enjoy their magnum potential. Third, I don't care about saving on my powder usage because I don't load for reasons of economics, that just wouldn't make sense with a magnum weapon, rifle or revolver.

    To elaborate on my choice of powder is pretty simple. The individual who wants even the lower end of the loading data with these type powders will always be loading high velocity loads. With the use of these type powders it is very probable to produce both accuracy and high velocity because the burn properties allow for a very different reaction on the bullet when it is gaining velocity and developing maximum pressure. This is actually what the cartridge was designed for, to obtain its full potential in all aspects, other than cowboy shoots. A good deal of the burn and pressure is beingachieved after the bullet has already entered the lands. That is the reason for accuracy potential with slow burning powders. I've shot these loads from my revolvers with a solid rest and am achieving groups that would amaze any experienced handgun shooter. It requires a lot of working up with each of my revolversto determine whichprocess suits each weapon. But in the end I'm having funin discovering just how much velocity and accuracy each of themare capable of, with lots of enjoyed time at the press, and on the range. One negative I always have to cope with, is the extreme amount of recoil I get with these full magnum loads. But that is what I'm expecting, and in some strange way, enjoy.

    I would like to take just a moment to quote a couple of experts on loading for the .357 magnum.

    Nosler-When loading for this cartridge we have always had best results using the following slow burning powders, AA- #9, 2400, H110, and 296. I use the H110 and 296.

    Sierra- The .357 mag. achieves its increased performance by a tremendous increase in operating pressure. The .357 mag. is at its best with large charges of slow burning powders. Faster burning powders, such as Unique and 231 allow much milder loads to be used for practice and plinking with SWC and other non jacketed bullets and results in severe leading.

    Hornady- H-110, 296 produced excellent results with jacketed bullets. Loading with lead bullets velocities should not exceed 900 fps and 38 special data must be used. Expect undesirable leading of the barrel after just a few rounds with lead bullets.

    Speer- The 110 gr. JHP at high velocity is an impressive varmint bullet. (For this bullet they are showing much lower velocities they consider to be high velocity, than most other bullet manufacturers are showing for some reason) Speer has always shown a more conservative load data than other powder and bullet manufacturer's?

    I would also like to point out that all of these listed manufacturers above and others I encourage you to review, made clear that loading below minimum powder chargeslisted for the slow burning powders will increase pressures dangerously. As well, they stated that loading low velocity for SWC or other non jackets bullets is not recommended for this weapon due to heavy barrel leading and unpredictable pressures with the faster burning powders required. Most also stated that the weapon operates at its best at the averageindustry standard (35,000 CUP) Maximum is at 48,500 CUP= 37,600 psi by SAAMI standards, and CIP 320 MPa = 46,400 psi.

    In the very end, I guess my final point to be made is, why would I own, and load for a magnum weapon, if I only intend to shoot substandard loads through it that are going to barely provide for my huntingand self defense needs??I do make one exception when carrying my weapon for self defense though,and that is a 125 grain Gold Dot loaded to 1450 fps to reduce possible collateral damage. The 2000 fps plus loads are for target and hunting only.

    I'll go side by side, and have done so,with anyone shooting their low velocity stuff on paper, and I will produce competitive groups with my snub nosed S&W.

    When seconds count, the police are only minutes away!

  5. #5
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    man you guys are awsome! makes a kid like me wanna handload.

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    so let me get this right. smaller powder charges produce higher pressures? how does that work?

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    Thats right Jeff.

    One of the most dangerous ways it works is instead of a progresive burn through the powder, from the base forwards, the powder lays in the case and burns across the larger surface area. the force of the bang is then mostly sideways and not where we want it.

    Because of the larger surface of the burn more fuel is burning at a given time so its going to be a quicker explosion giving a sharper higher pressure curve.

    Sorry if I've made that a bit simplistic but should give an idea of whats happening in the case.

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    Yes Jeff, that is partly correct and I'll elaborate so as to prevent you or anyone else from making a very serious mistake of which I've personally witnessed.

    First let me clarify a little bit about various powders and what is referred to as burn rates. For example,you see data for the .357 magnum that is for Bullseye powder, which is considered a fast burn rate powder for this particular cartridge, and the stated charge is between 7.1 grains to 8.4 grains using a Sierra 110 grain jacketed hollow cavity you would definitely not want to ,or decrease that loa,d beyond its maximum, or minimum, stated charge. To do so would create some very unpredictable pressures that would most likely be extremely high.

    However, if the data you utilize is referencing H-110 powder, a slow burn rate powder for this application, your charge would be between 18.5 grains to as much as 20.4 grains. This is where you will begin to experience the advantages of using a larger charge that will maintain consistent pressures, and velocity that will also deliver surprising accuracy. On the flip side of using these slower burning powders one must not reduce the minimum recommended charge as this will surely cause an unpredictable rise in operating pressures.

    I always recommend using the minimum recommended charge with any powder you have not previously worked with, as this will allow you to develop the charge that best suites your shooting application. This is also a sensible safety measure, as not all guns react exactly the same way with identical loads.A good example would be the design variations between my S&W 66-5, and my Taurus 608 revolvers. The S&W has a very tight bearing surface in the cylinder,so tight that abullet of exact size and weight will slide easily through the cylindermy Taurus, but won't in my S&Wand must beforced through. Obviously two identical loads will work very differently in each of these revolvers.My S&Wreaches most of the obtainable pressures for a given charge, inthe cylinder. The Tauruson the other hand will reach most of its obtainable pressures for the same charge, primarilyin the barrel. This doesn't make one gun any safer than the other, but itwill cause projectedpressures to vary and change the point of such variation in the weapon as well.

    I apologize for any dilemma I may have created for you by over stating the characteristics of gun powders, and how they physically respond to what ever application they are being utilized for. But it is just too easy to misunderstand powder recommendations by just simply saying, the more you use the better it will work. And I'm sure I'm not finished establishing my points of interest as the following will certainly support. It is obviously some what more complex than that, but also simplistic when following reliable posted reloading data, as should be the number one rule for picking a charge for any application. Never, never, develop a charge for any gun without following the specifics for each component being used. Changing primers, powders, bullet type/ manufacturer requires using data specific to those criteria, always! My opinions and those of others should be scrutinized by you. Check them against a good reloading guide, such guides areavailable from the powder, and bullet manufacturer's. They have tested their data using the best of technology and equipment available, making each stated load as safe as possible when used in a a firearm of good quality and in safe working condition.

    Good luck and know that myself and others are always available for questions you may have. And if we do not have the information you request I'm sure one of us will know what direction to send you in to get that information.

    FYI, my State of Arizona just passed it into law that we can now carry concealed without the need for a permit! It was signed by our wonderful Governor last week and already passed the state senate. It is official and will take effect in 90 days!!

    When seconds count, the police are only minutes away!

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    thx for clearing that up. i always though, that the more powder in the case, the more gases created during burning and thewrefore more pressures and high velocities.

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    There is also a matter of the speed at which the powder burns, this makes a huge difference in the amount of powder that is used. The case volume, bullet weight, bullet type, bullet material, seating depth, and even how heavy of a crimp is used are also all very important issues in how much pressure is generated.

    I have found the most accurate handloads in my 243 to be right at the max load data so I know that although most people say that velocity and accuracy are not usually travel companions but for my 243 they are.
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    i think i'll leave the ammo to the guys at hornady

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    I couldn't agree with you more. Most of my most accurate loads for my rifles and my handguns is the close too, or at max data. And as you stated, we will always be scrutinized for our higher velocity loads, as well, doubted I would assume.

    Also, regarding your understanding of powder, seating depth, type and degree of crimp, components, and other very relative information is right on the nose in my book. I'm not sure that their are enough reloaders out there that understand how very important the entire process is. I state this based on my personalknowledgeof other reloaders that havebeen injured or destroyed weapons.If one is expecting certain results, and as well, wanting to avoid the ultimate of negative results, ( injury and firearm damage) then taking all aspects of the process as, must do's, is the only safe and fulfilling method to approach the task, and hobby with.


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    I only in tend to learn to reload for when i start putting together my precision rifles and hopefully one day a cheytac .408. factory ammo works fine in my DDM4 and HK USP

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    I've considered loading for those two for reasons of economics,but keep thinking about how cumbersome it would be. I have one of the Rock River LAR15 M4models and ammo is very available, but a biton the expensive side when considering how quickly a 30 rd. mag. can be dispensed. Are those both a 5.56 or is the HK one of the 9mm models? I'm not all that familiar with these weapons.

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  15. #15
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    my m4 is a 5.56 and my HK is a .45 (pistol)

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