Reloading data. Always way off?

[Wheelgunner840]

I have been reloading for a long time. I have also made a habit of chronographing my loads. I got into that habit because when I shot IPSC years ago, we needed to make sure our loads made "major" power factor.

I check the data listed by the powder manufacturors on a regular basis, especially if I am using a new bullet style and weight. I came across a great deal on some .357 148gr. LWCHB heads. I was looking to create an easy shooting yet very accurate target load. After pouring over the data from several sources, I decided on using W-231 powder as I have a lot of it on hand.

4.0 grains seemed like a great place to start, as I have used this load under 158gr. SWCs in the past. That load was not especially stiff, and these bullets weighed less.

I chronoed them today, and got 750 fps out of the snubbys (actually 757 from the Dick Special, and 705 from the model 36). I got 800 fps out of the 4" bbl. mod 28-2.

That seemed like a fairly light to medium load. Now for the powder manufacturors data. They claim the same loading with the same bullet is a max load that will yield 956 fps.

I know it was fairly cold out today, but not excessively so. About 41 degrees. Most of my loads run faster in the summer with W-231 than the winter, but usually no more than 50fps difference. But, 150fps difference???

I realize that they may be testing with an 8" bbl. but that is a huge difference. Are they that worried about lawsuits? I would rather have accurate loading data and have people be responsible for their own actions or stupidity.

Anyone else finding major discrepancies between the data and actual results?

 

[sonny]

I guess you're using a snubbie and the other guys probably are using a longer test barrel; perhaps 6-8" as you say. That is quite a difference, but as long as you chrono, I think you're golden. That's all you can do, and you know your answers are good in your gun.
Sonny

 

[Bruce51]

I have two .357's with four inch barrels. The newer 686 is consistantly 75-100fps faster than the much older model 19 with equal loads. Every gun and every load will probably give a different reading. That is not even taking into account hot or cold weather or all the other posssible variables. Half the fun is just finding out how it all works in a particular gun.

Bruce

 

[OKFC05]

Anyone else finding major discrepancies between the data and actual results?

Unfortunately, if you don't know what length and type of barrel was used, the velocity estimates are almost worthless. I have to believe that if I had the exact same barrel that they used, I would get essentially the same results. However, an unvented 10" test barrel is so far from a 4" S&W revolver as to be meaningless to me.

 

[Wheelgunner840]

I pretty much had come to the same conclussion as far as variables go, but to be off by 150 fps is just crazy. Why would they even think about using a 10" bbl. to test loads that will in all likelyhood be shot out of a 4-6" bbl.?

I realize that all guns are different as well, but it just seems that the powder makers are being overly cautious with their data. I would much prefer getting honest results printed. I don't think I could get this loading to do 956 fps out of a rifle!

 

[Paul5388]

WG,

The 10" barrel is used to make the velocities more impressive.

I use a max load for a 125 gr bullet that's found in S**** #8. The manual says it generates 1617 fps and I clock it at 1620 fps. That's with a 6" barrel, just like the length they used.

Of course, the older manuals tended to give actual results instead of this inflated junk they put out now.

 

[MDaly]

In the 357 Mag a 10" unvented test barrel for a universal receiver is used because that is the SAAMI standard test barrrel. When this cartridge was standardized under SAAMI, Remington (the submiting company) specified a 10" test barrel of certain dimensions. That makes it the industry standard. Why did they do this? Who knows but they did. This also allows for the creation of reference ammunition which is used to calibrate the barrels, transducers and calibration fixtures. This way, any testing station in the country can develp ammunition in calibrated test equipment.

MDaly

 

[WR Moore]

In addition to the comments already made, the test barrels are specially machined to finishes/tolerances not seen on production weapons. Chambers are cut to absolute minimum to produce a worst case scenario with respect to pressue. FWIW, I've never, ever in 40+years, managed to get the velocities the powder manufacturers claim I should get with a given charge.

Where possible, all testing is done at STP or "standard temperature and pressures" and published data is generally corrected to give muzzle velocity rather than the velocity at whatever distance your chrono is at.

The other issue is your chrono itself. I rather doubt yours is in the same price range as those used by the various manufacturers. More to the point, theirs (at least the ones using universal receivers) are set up to put the bullets across the chrono on exactly the same dead level path each and every time. Variations in the path your bullet takes across the sky screens can make some really interesting
changes in your recorded velocities.

Trivia: I've still got a ballistic pendulum used in the early days of IPSC. Chronos won out in part because variations in bullet hardness could affect the results negatively for those skirting the line.

 

[leon riverrat]

I recently had some 38/44 loads tested by H.P. White lab. Their velocities ran some 100 to 150 fps faster than the same loads tested in my 6" barrel revolver. The lab used an 8 inch test barrel and 2 pairs of screens set at 5 and 25 feet. Velocities were averaged and recorded as 15 feet which was about the same distance I used for my testing.

 

[Jellybean]

This is why I cringe when I see someone suggest to use a chronograph to work up loads without a full explanation. By the time a reloader works up a load to the velocity he/she "thinks" they should be getting, their pressures are way over and there is no way for them to check it.

 

[Paul5388]

This also allows for the creation of reference ammunition which is used to calibrate the barrels, transducers and calibration fixtures. This way, any testing station in the country can develp ammunition in calibrated test equipment.

Any barrel you chose to use that has been calibrated with "standard" ammunition would be just as accurate as having to use a 10" barrel.

Test barrels, built according to SAAMI specs, don't yield the same results, even with "standard" ammunition. That's one reason they report MAP (maximum average pressure).

 

[GLV]

Reloading manuals

I use manuals, rather the the manufacturer handouts. They give the gun or fixture used, and if a fixture, note if it was vented or not.

 

[running iron]

I bought one of those "complete book of reloading" for each caliber I reload. That way I can see every companies idea of what a proper load should be. It seems that the bullet makers, Sierra, Hornady, always give a more realistic point of view and are not as conservative as the powder makers. It is a pain to have to look at so much data to find a good load that is accurate and safe at the same time without being too conservative.

 

[Wheelgunner840]

Jellybean;
This is why I cringe when I see someone suggest to use a chronograph to work up loads without a full explanation. By the time a reloader works up a load to the velocity he/she "thinks" they should be getting, their pressures are way over and there is no way for them to check it.

When loading the .38 Super for IPSC competitions, we needed to make a 180 power factor. (Bullet weight X velocity divided by 1000) That meant a 125gr FMJ flying at just about 1450 fps. We all made sure that our ammo would make "major". Thankfully a few years ago they lowered that number to 160 PF which would be just under 1300fps. I used VV N-350 back then and had no pressure problems.

I no longer shoot IPSC or IDPA, so making a PF is not and issue. I do have some older reloading manuals hanging around, and I think I might just do some comparisons.
I never exceed the max loads as listed, but as I said earlier, it would be nice to have accurate data to begin with.

Thanks for all the replies folks!

WG840

 

[Bruce51]

Test guns

This thread got me looking back into the manuals to see which one listed a four inch test gun. The Hornady third edition lists 38 Special loads out of a four inch S&W model 15. From the data listed in appears to at least be closer to real world velocities we might expect in a similar gun.
Some of their other data such as a 9MM S&W 39 lists loads close to what I chrongraphed in a 639.

I think I'll use the Hornady book a little more often now that I see the data from guns like I shoot.

Bruce

 

[canoe on the yukon]

In my opinion,every handloader should own several manuals from various sources.Much of the confusion I note on the forum comes from those who obviously use very few (or perhaps even just one) sources for data and this inevitably leads to tunnel vision.Powder company manuals are not without fault on several levels.Better to have a variety.Much misinformation and myths usually come out of a limited scope of exposure.To put it bluntly,many loaders/shooters know just enough to be totally confused.(and many of them don't know they're confused)

I have an old (about 40 years)Lyman cast bullet manual that gives velocities with the 429421 using Unique and 2400 that are so close with one of my gun's that it's hard to believe but this is almost certainly a coincidence.

Generally speaking,I find the component/velocity figures to be much closer with revolvers in the Speer,Sierra and Hornady manuals although in recent years,I find the Speer manuals to give higher velocities than any revolver I've tested.

Bottom line...get several manuals and use common sense when developing a load.

Barrel length certainly matters but there are so many other factors that one shouldn't predict too much from it.There are 4" revolvers that will chrono faster than some 6" revolvers.

Broaden your exposure and things will become clearer.

 

[Steve C]

HBWC's are for low velocity target loads and not meant for anything but accurate loads at relatively low velocity.

One thing to remember about HBWC's is that you are expanding the skirt to seal the barrel. Too heavy a load can make the bullet excessively tight and can even rusult in the skirt tearing off creating a dangerous bore obstruction.

The Speer #13 manual lists 3.3grs of W231 as maximum for their 148gr HBWC and the range of 3.0 to 3.3 gr with velocity at 749fps to 806 fps.

I'd suggest you try dropping your load to between 3.0 to 3.3 grs and run them over the chrono to see if the velocity doesn't stay about the same 750 - 800 fps from the longer barrels. If you do, let us know the results.

FWIW a load of 3.1gr W231 behind a Speer 148gr HBWC lit by a WSP primer in miscellaneous cases averaged 740 fps from my S&W M66.

 

[Wheelgunner840]

Canoe on the yukon, thanks for your input. I agree with you on having as many resources as possible. I have mostly Lyman books going back 10 years or so to present, and many, many powder manufacturor pamphlets. Along with these, I also have printed out many load data pages from the web and keep them in a binder. I also look to see what people have to say on the forum.

Steve C.
I had toyed with the idea of dropping the load to 3.5. I will load some at that charge, and some at 3.3 and chrono them. The guns used are mentioned above, but here they are again. Model 28-2 with a 4" bbl., and two snubs. A Colt Det. Special, and a S&W Model 36.

I will post results.


WG840

 

[josephthreedogs]

I was told by A Sierra bullets tech that loading manuals were not recepie books but reports of how a combination of components worked on one partticular day.

 

[fredj338]

You can't possibly expect powder manuf to do test data in all the possible bbl lengths. They often use what they have & vel always looks better out of a long bbl. Throw in that no two revolvers or even pistols bbls are the same & you can see 150fps diff between guns of the same manuf & bbl length. You just have to extrapolate form what the test data gives you.