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Thread: Published load data way off?

  1. #1
    Boolit Bub
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    Published load data way off?

    Is it just me, or is the published load data, way outside reality?
    Been working on some 44 sp and 38 loads.. using mfr and other published data, I'm getting 25-30% lower velocities. 200 gr cast hp over 6.6 of universal is supposed to be up over 950. I'm barely getting 700 using a 190 cast hp. Same with unique and bullseye. As bad or worse in the 38 sp. even looking at barrel length. (4" in both) something doesn't seem right. Or are the lawyers pushing the caution buttons for people publishing reloading data..
    Changed batteries in the chrono. Even shot some rifle and factory loads and it seems to be pretty accurate.

  2. #2
    Boolit Buddy Went2kck's Avatar
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    if you powder is old and in high humidity maybe it has degraded and lost some power. Just saying.

  3. #3
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    Just a thought, try some fmj and check and see if maybe your Chrono might be off

  4. #4
    Boolit Grand Master Outpost75's Avatar
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    Velocity data taken in a solid pressure test barrel WILL be higher than revolver.
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  5. #5
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    Quote Originally Posted by Outpost75 View Post
    Velocity data taken in a solid pressure test barrel WILL be higher than revolver.
    This....
    "Freedom is never more than one generation away from extinction. We didn't pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same......." - Ronald Reagan

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  6. #6
    Boolit Bub
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    Quote Originally Posted by Outpost75 View Post
    Velocity data taken in a solid pressure test barrel WILL be higher than revolver.
    Thanks. I had that experience for the 50 years I've been loading (test bbl vs real guns &#128522
    But even tried the loads claiming to have been clocked in revolvers with similar bbl length. The Pearce article on the 44 spl, data for instance. Not getting anywhere near the performance from 4" bbl. Hate to just keep jacking up the loads. Trying to get a decent 800 fps knocking around load with light hollow points. Even tried a few of the favorite loads from the CB folks here.
    Some of my powder is older, but some is fresh.
    I'll check the chronograph again.
    Have checked loads that were put together many years ago and seem to have the same performance as when loaded. Never noticed any deterioration in powder that was sealed and stored indoors. Maybe the newer stuff isn't as stable as they used to be?
    Thanks for the input.

  7. #7
    Boolit Master buckshotshoey's Avatar
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    Try a version or two of factory loaded rounds through your chrony to see if they are comparable to your reloads. That should show if it's a chronograph problem.

  8. #8
    Boolit Buddy
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    .22 match ammo is very consistent and is great for checking a chrono

  9. #9
    Boolit Master
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    If the spacing between the skyscreens is not exactly what it should be, you will get false readings.
    It's all chicken, even the beak!

  10. #10
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    what data are you using cast or jacketed
    Hit em'hard
    hit em'often

  11. #11
    Boolit Grand Master OS OK's Avatar
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    I had a Smith no.3 in .45 Scofield that had such a wide barrel-cylinder gap you just couldn't make any horsepower with it.
    Traded it in on another 1911.
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  12. #12
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    Quote Originally Posted by Outpost75 View Post
    Velocity data taken in a solid pressure test barrel WILL be higher than revolver.
    This ^^^
    As well as, COAL effecting amount of empty case space, compounded by boolit weight and size and style variations.
    Add to that, how much you are expanding the case...effecting case tension, as well as crimping or not crimping the case. There are many things you could be unknowingly doing different than the publishers, to get lower velocities.
    ~~~~~~~~~~~~~~
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  13. #13
    Boolit Grand Master Outpost75's Avatar
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    Quote Originally Posted by Paper Puncher View Post
    .22 match ammo is very consistent and is great for checking a chrono
    This is a sound procedure which anyone can do. I keep a brick of old paper boxed Eley Tenex and shoot a string through my 6-7/8" barrel High Standard Model B every time as an instrument check. The ammunition factories follow a similar calibration procedure with specially-loadad SAAMI "Reference Ammunition" in the respective caliber, in which everyone in the industry fires a round-Robin test procedure, turns in their data and the large sample size is statistically evaluated, the values provided and a procedure used to develop and apply, when necessary a "correction factor" to sample observations which fall outside of the prescribed parameters.

    In revolver ammunition some calibers such as .38 Special and .357 magnum are often tested in a two-piece "vented" pressure test barrel, in which the chamber is a separate section, connected in a fixture to maintain a constant 0.008" cylinder gap, which presents conditions similar to a revolver. This procedure was often specified for certain law enforcement ammo made under government contracts, but was not applied universally.

    The powder companies testing load data for their products and who like to show an attractively high velocity figure for marketing purposes very commonly use a 6-inch solid test barrel in most calibers as a matter of convenience. Such a barrel can be expected to give a velocity average about 80-100 fps higher than a 4-inch vented test barrel maintained at the conditions which were commonly specified for accepting law enforcement ammunition back in the day when revolvers ruled the world. There is very seldom a contract "requirement" anymore for testing revolver ammunition in the vented barrel, so it is seldom used anymore.

    The usual expectation in calibers such as the .38 Special, in standard pressure loads, is that the velocity difference is about 10 fps for each 0.001" change in barrel length from "Mean Assembly Tolerance," which is generally 0.005" in a new revolver before proofing. It is normal that some minimal setback up to 0.001" to occur after proofing and targeting, especially in .357 magnums, so "pass 0.006" in which a 0.005" feeler gage can be inserted completely through the cylinder gap, and the trigger pulled and the cylinder rotated a full revolution without resistance, and "hold 0.006" in which the 0.006" gage can be inserted completely through the cylinder gap, but the cylinder will bind when the trigger is pulled, with the "rear gage" in place. The rear gage being a set of max. cartridge headspace gages.

    So you will also see the 0.006" figure given as MAT, the difference being that the 0.005" is for WIP (work in process) and 0.006" for FQA (Final Quality Acceptance).

    Therefore it is ALSO very possible that you could have a 2" revolver with cylinder gap of minimum tolerance of 0.003" cylinder gap, which produces higher velocity than a 4" gun having a maximum cylinder gap of 0.0008". Many used guns having seen heavy use will have cylinder end shake exceeding 0.002" and cylinder gap exceeding 0.008" which will give as much as 100 fps lower velocity than a new, tight gun at minimum fit-up specs.

    This is why revolvers drive ballisticians NUTS!
    Last edited by Outpost75; 08-18-2017 at 11:04 AM.
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  14. #14
    Boolit Grand Master

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    Reloading manuals are not hard and fast formula. They are the results of the components used, with the equipment used in a lab with the listed powder charges. Your results will vary. It's surprising when home reloaders' results are identical to published manuals...
    My Anchor is holding fast!

  15. #15
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    I see the Lyman Cast Bullet Handbook #4 has 38 special tested in 4 inch barrel universal receiver.
    The 44 special is tested in a 4 inch and 7 1/2 inch universal receiver. So the fps are not going to be the same as when fired from a revolver.
    Just read the fine print and take those fps with a grain of salt.
    The pressure is the number you want to pay attention to, don't go over max.
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  16. #16
    Boolit Bub
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    Quote Originally Posted by buckshotshoey View Post
    Try a version or two of factory loaded rounds through your chrony to see if they are comparable to your reloads. That should show if it's a chronograph problem.
    Tried that with my 3" beretta 22 (975 fps) and ppk 380 (850 fps). Both seemed about right.

  17. #17
    Boolit Bub
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    Quote Originally Posted by mdi View Post
    Reloading manuals are not hard and fast formula. They are the results of the components used, with the equipment used in a lab with the listed powder charges. Your results will vary. It's surprising when home reloaders' results are identical to published manuals...
    Thanks for all the great and thoughtful input. I started reloading in the early 60's, buying components and equipment from Herters. And anywhere else I could find it. Showing my age here . And yes, has always had variations in published data, one way or another. Though in the early days we didn't know because we had no way to measure performance of our loads, other than accuracy, trajectory and effectiveness on game.
    But those variations were usually a matter of 5% or less, never over 10.
    In these 2 guns I'm getting 25-35% under published data (cast and jacketed). Both 4" barrels.
    What little experience I've had with powder deterioration in sealed canisters, actually resulted in hotter burning characteristics as the coatings that were used to control burn rate deteriorated or sloughed off.
    The older bullseye powder is slightly cooler than the new stuff. Have tried both. I'll be trying a 7.3 grain load of universal over a 200 cast 44 sp. and 4.5 gr over a 145 cast in the 38. Have a 624 6.5" on the way. Will try that one as well. Been using my fly fishing gun. A charter 44 sp. bulldog 4" and my favorite 38, a 4" S&W 67.
    Thanks again for all the input!
    Greg

  18. #18
    Boolit Master buckshotshoey's Avatar
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    Quote Originally Posted by brayhaven View Post
    Tried that with my 3" beretta 22 (975 fps) and ppk 380 (850 fps). Both seemed about right.
    As long as you got fairly consistent readings, I wouldnt blame the chronograph. As said above, it is probably the test barrel used, or the cylinder gap in your revolver, or most likely a combination of the two.

    As long as you are getting consistent velocities out of that revolver, it is what it is. I wouldn't worry about it. Have fun.

  19. #19
    Boolit Master trapper9260's Avatar
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    As for what is stated ,also the reloading data is only a guide.
    Life Member of NRA,NTA,DAV ,ITA. Also member of FTA,CBA

  20. #20
    Boolit Buddy
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    I can't usually match Hodgdon's ten inch pistol barrel either.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check