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Old May 6, 2001, 04:24 PM   #1
Nanaimo Barr
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ok, brand new reloader (my wife is a CAS shooter and we go through a lot of ammo).

Lyman Turret press, Hornaday Delux Powder Messure, Lee Carbide dies, .357 nickled brass, 158 gr Lead SWC (Montana cast), 5.5 grains of Unique. according to my Speer 13th edition, that should have given me about 970 FPS, with a borrowed chrono I was getting mid - high 1200 FPS.

comments? sugestions? words of wisdom?

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Old May 6, 2001, 04:52 PM   #2
Art Eatman
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I looked in Mr. Speer's manual #13, and you're right on the money. If I wuz gonna make one of my famous sorta-scientific wild-eyed guesses, I'd say that since his load is for a jacketed bullet, and you're using cast lead bullets, you're getting the higher velocity. (Softer metal = less resistance in the barrel.) Off the cuff, the difference is a bit startling, but that's about the only reason I can think of.

Reading further in the book, I see a .38 Special listing for 4.7 grains of Unique giving an MV of 815 ft/sec, for a lead bullet. This is shown as a max load in the Special.

I dunno. Try 5.0 and see what happens.

FWIW, Art
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Old May 6, 2001, 05:24 PM   #3
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NB...This is OK if pressure was safe(what condition was primer...was extraction easy?) in a modern .357(reviolver ? you don't say in your post) in good condition.

The profile/type and diameter of the bullet, seating deapth(was the W/C flush by any chance... or depressed!!!?) and a heavy crimp also will affect velocity and pressure.

Your mate's Chrono could need re-calibrating maybe? Was it far enough away from the muzzle?

Check OAL and chamber/cylinder dimensions and also barrel fouling and THEN use 3.8gn and work up....!

Recoil and blast should have quite a sting in it at 1,200+ FPS -did it? Get a buddy who knows the round to check yours out by trying a shot or two.

Pressure is the (KaBoom) "killer" - not velocity.

Tabulate all your data as you go - of course.

My 5C worth. Let us know how you go.....
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Old May 6, 2001, 05:43 PM   #4
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Just so you know...

lead bullets generate HIGHER pressures than jacketed. I think its that the bullet seals off the bore better, and the soft metal drags more, but lead makes MORE pressure, not less.
It's counter to what I used to assume, but such is the way of the world.

If you are getting more velocity, you are generating more pressure (all factors being equal). There ain't no free lunch, it has to be that way.

Start with the starting loads. One, or several hundred overloaded rounds won't blow up the gun. Unless it's a cataclysmic level overload. However, a diet of minor overloads will beat your gun to death much sooner.
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Old May 6, 2001, 09:02 PM   #5
Nanaimo Barr
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wow! to all Mucho Thanks! the load I got from Mr. Speers book is for 158 gr L-SWC, (Page 527 of the 13th Ed), good thing I started with the low end, for Cowboy Action Shooting the rd has to be 1000 FPS or less for pistol and 1400 or less FPS for Rifle.

Big Bunny: I tried them in a Rugar Blackhawk and a Rugar Vaquaro, extraction was easy, had one dud (I suspect that I missed the powder on that one), Primers looked ok as near as I can tell. the Bullet seemed to be seated ok, possible I put too much crimp on it. as for the Chrono, about 10-15 foot distance, lots of errors on the first 2 sets of 5, last set of 5 all came out in the mid 1200's, pistols had been cleaned. recoil was maybe a wee bit less than previous loads

Mr. Eatman: well, maybe I need to go with .38.. but I got a great deal on 1500 nickeled brass for .357 and my wife likes the way they look on her gun belt, something about "Hi Ho Silver AWAY!!!!!!!!!)

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Old May 6, 2001, 10:17 PM   #6
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OK amigo.....glad you are still ok !

I am unconvinced over linotype vs gildingmetal projectile question -as regards pressures. I would think they would be nearly /practically equivalent for similar lower velocities, if diameter was the same, [often lead is +2thou oversized for accuracy in target loads].

Maybe NB also consider staying away from fluorescent lights(gives inaccurate readings with any chrono) and use a new longlife battery too!

The capacity of a case also affects pressure. Weigh water in case on a bullet/powder scale and then compare against a standard brass (-not cadmium plated) case maybe.
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Old May 7, 2001, 01:38 AM   #7
Mike Irwin
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Archie,

Lead bullets MAY generate higher pressures than jacketed, but not always.

Generally, pressures with lead and jacketed bullet are in the same ball park.

Lyman's 47th edition Reloading Handbook has pressure data included as part of its loading specifications, and many lead bullet loads show pressures lower than with similar weight jacketed bullets using roughly the same powder charges, others show virtually identical pressures, and other loads show higher pressures.

There's simply no easy rule of thumb.
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Old May 7, 2001, 06:00 AM   #8
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I believe your chrono readings are incorrect.......

I firmly believe this (but I may be wrong).
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Old May 7, 2001, 02:57 PM   #9
Cheapo
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Lighting conditions?

One afteroon as the load testing concluded, I decided to run a few of my hot .357s over the Chrono again. What had been a nice, stout 1375 fps load using a Speer 146-gr jswchp, was now doing 1800+FPS!!!

Sure, it was hot that day, but recoil, blast and muzzle rise still appeared as before.

On shot #4, it went up to more than 2,000 fps, and I could see that the 50-yard point of impact was still unchanged. What's up???

Then I noticed that my back was to the sun and the shadow of my revolver, at 6 feet back from the first screen, was passing only about a foot below the screen. I aimed lower and closer to the screens, and got a 1500 fps reading.

Problem??? The gas cloud from firing the shot was casting a shadow over the first and second screens in a VERY short time, far shorter than the bullet would. Eliminated muzzle blast bouncing the diffusers as a potential cause by turning the direction of fire 90 degrees--all other factors being the same, I got nothing but high 1300s for the remaining readings.

I vote for Chrono error, even though lead bullets usually shoot faster than jacketed, with equal powder charges.
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Old May 7, 2001, 09:31 PM   #10
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Cripes Cheapo!.... uze mus be using th' ol' BP in your wheelgun loads partna!

Seriously - I vote for operator error on the Chrono too.

But I feel it is often a shame that when a FL poster solves "his problema" on this BB -they rarely come back and tell us here whether we wuz right or wrong!

Ah well.....
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Old May 8, 2001, 12:47 AM   #11
Johnny Guest
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So Many Items to Discuss--So Little Time.

Nanaimo Barr--

Your msg raises all sorts of interesting questions. I don't have a Speer #13 at hand, but do have a #12. I see the very load you mention, 158 SWC with 5.5 Unique for 970 fps. Looks much like some of my chronograph work.

Can you furnish some more information about gear and technique? Type chronograph. Distance to start screen. Distance BETWEEN screens. Montana cast bullets--I'm not familiar with this brand. What kind (or color) of lube is in the grooves of these bullets? Is it easily dented/removed with a fingernail?

Cheapo raises excellent points about the smoke cloud causing reaction, rather than the passage of bullet. I would bet that the problem source will ultimately be found somewhere in this area. How were you oriented with respect to the sun? What time of day was it? Was battery in chrono fresh?

Nanaimo, you write that you used a borrowed chronograph. Did you check with owner to see if the electronics box has had any interesting impacts?

You gave us powder measure type, and this sounds fine. What kind of scale or balance did you use to set it? Did you zero the scale carefully? (Hopefully with check weights.)

Blackhawk and Vaquero revolvers--How long are barrels on these?

Also--and please, I intend no offense here--you say you are a beginning handloader and that the chrono was borrowed--might it be that results would have been different if a more experienced operator had been present to supervise? You mention "about 10-15 foot distance." Was distance identical for each string? Did you have the chronograph manual available? It is easy to make minor errors which combine to give grossly distorted results.

Archie---I must ask where you got the information that lead bullets give higher pressures than jacketed bullets? Not impugning YOU, sir, but your sources. I just don't believe this is the case. I've had occasion to remove several stuck bullets from barrels over the years, and it takes a LOT more force to move a 230 gr. FMJ .45 bullet through a bore than a very similarly-shaped lead bullet of same diameter. And, though I cannot quote sources here, I've read a formula to allow calculation of approximately how much MORE resistance there is with a jacket bullet than from a similar lead bullet, both pure and with a hard alloy.

Art--
You wrote, "Reading further in the book, I see a .38 Special listing for 4.7 grains of Unique giving an MV of 815 ft/sec, for a lead bullet. This is shown as a max load in the Special."

Wow--In the previous edition of same Speed manual, it shows same load at 913 fps.

Next time I go to the range, I'll try to duplicate this situation. I'll bet it has something to do with the lead bullet/Unique powder combination. This is a notoriously smoky combo (No, NOT particularly DIRTY, just smoky--) and one which may contribute to the erroneous readings. The more I think of it, the more I believe friend Cheapo may be on the right track.

NB, presuming you used proper care in assembling your loads--and the load is certainly a low- end magnum load--the problem nearly has to be in the chronography, either technique, operation, calibration, or disrepair of the instrument.

Best regards,
Johnny
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Old May 8, 2001, 11:06 AM   #12
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Johnny Guest, I wish I had my references handy, because I once knew from published pressure data (Alliant??) that max published loads for the same powder ran from 0% to 5% less in charge weight for lead bullet loads, as compared to their jacketed bullet loads for the same bullet weight.

True, some of this may be attributable to differences in bearing surface.

I've *heard* that at smokeless powder pressures, the accelleration of the lead slug causes continued obduration of the metal against the bore, resulting in greater a duration and magnitude of friction for lead bullets as compared to jacketed bullets. The initial resistance of jacketed is higher, as the rifling engraves the jacket, but once that operation is complete, the jacket resists the radial "slumping" of the lead and results in less overall friction and lower pressures, which in turn require a small increase in powder charge to reach the same velocity.

Maybe some metals expert engineering type can confirm this theory for us. Sounds plausible to me, especially since we need to keep velocities below 1500 fps for a certain 165-gr cast .30 rifle bullet because its pointy nose (no bore-riding forward shank) fails (slumps) under accelleration. Accuracy goes to pot.

Remember how Moly bullets take more powder to reach the same speed? Less friction = less pressure = less velocity, without a compensating increase in powder charge.

So....the general trend I have seen is that lead bullets *usually* take a bit less powder to reach max pressure and velocity than comparable-weight jacketed bullets. One illustrative exception, IIRC, was 125-gr bullets in .357 Magnum using WW-296. Remember, that's IIRC!
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Old May 8, 2001, 11:47 AM   #13
Mike Irwin
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Johnny & Cheapo,

Go back and read my post again.

It's a variable thing. For some reason lead slugs CAN give higher pressures than jacketed with the same loads.

In other loadings, they'll give lower pressures, and in others, virtually identical.

The general rule of thumb is, though, that lead bullets will give lower pressures, but again, that is NOT always the case.
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Old May 10, 2001, 11:26 AM   #14
Nanaimo Barr
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sorry I didn't reply sooner, been having some very confusing computer problems...

with all the comments and sugestions I think the chrono may be the problem, my current plan of action is to make up another batch of the same rounds and have a friend (who knows how to use a chrono right) run it through a differnt chrono and see when happens.

I thank you all muchly for all your comments and advice, I learned a lot from the "side" discusions as well.

when I get the next batch done and shot off I'll get back to all you fine folks and let you know what all happened.

NB
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Old May 10, 2001, 11:49 AM   #15
Cheapo
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Mike: The Winchester reloading guide, as fars as 170-gr bullets in .40 S&W using 231, backs me up. You may want to look up other references that include pressure data (Alliant, IIRC). The differences are as low as .1 grain in some instances. From what I've read, lead more often gives higher pressures for equal powder charges.

Big Bunny--although I stated it as being the gas cloud fouling up the skyscreen readings, further thought makes me believe it could 'ave been the shock wave in front of the gas cloud. The air out here is clear enough that you can see mirage waves on the ground, from the noonday sun, and skyscreen pointed up at the deep blue sky may not get enough other wavelengths to register the bullet, without adding a diffuser screen. It's a temperature and atmosphere thing.

No blackpowder needed to mess up the readings.
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Old May 11, 2001, 03:59 AM   #16
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Howdy,

Wanted to drop in my 2 cents. Given the powder and bullet weight vs. the claimed velocity. I also favor Chronograph probs.

However, I also wanted to add that I have become suspicious of the Speer reloading manuals, particularly the pistol data. I invariably get substantially higher velocities over my Ohler chrony than the Speer book lists for given charge and bullet weights. Yet, when I load by the Hornady book it is usually right on the money for velocity spread by powder charge weight.

Maybe my guns coincedentaly like Hornady data better

Just another reason to stock your bench with a variety of reloading manuals and start any loading process with a review of the loads the various books recommend. If you find one that deviates substantially on powder charge weight for a given powder/bullet/primer combination, then in my mind it is suspect.

Molycoating needs more powder too provide more velocity? So, if i took 2 identical loadings of 22-250 ammo. (i.e. same case, primer, powder weight) But one bullet was molycoated and one wasn't......They would have the same velocity?

Intuitively I would think anything that decreased friction would increase the velocity of a bullet......

Brighter minds than me....chime in please<g>

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Old May 11, 2001, 09:21 AM   #17
Mike Irwin
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Doctari,

That's pretty much how it seems to work with moly coated bullets.

My own limited (OK, VERY limited) experiments with molycoated .243 bullets showed about a 150-fps drop when using the moly.
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Old May 12, 2001, 07:41 PM   #18
Nanaimo Barr
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well, latest update, due to scheduling conflicts couldn't get the loads chronoed, but time was short and I rolled up about a hundred, the wife shot off about 50 and said they felt the same, acted the same, and seemed to be the same as the batch we bought. (only more reliable, Grin), however, I have learned much from this thread.. so I thank you all for that. and I am going to be picking up a few more reloading manuals as well.

next thing.. cleaning brass....

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Old May 12, 2001, 10:49 PM   #19
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Nanaimo there are a couple other things that I didn't seem mentioned, did you perhaps use magnum primers with those loads? If you did that could account for the difference between the listed velocity and what the chrono measured. Another thing is to pull the bullets from a couple of your rounds and weigh the powder to confirm that you actually did have 5.5gr of Unique in them.

Assuming you used standard primers and didn't have a problem with your loader tossing to much powder I'll go along with the others and say the problem is with the chronograph.

Let us know what the second round with the chrono results with.


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Old May 16, 2001, 06:58 PM   #20
Nanaimo Barr
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JohnK, I used small pistol primers (CCI) and the first 20 that I ran through the chrony were messured on 3 differnt scales (to make sure my used scale was on), the second batch I weighed every 5th rd as I rolled them up. no problems with those.. and my bud with the good chrony and I just can't seem to get our schedules together.

NB




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