load discrepancy???

[jbc]

lyman cast bullet handbook 3rd edition(current)-

#429421 (245gr keith) max load of 2400 - 23.4 grains for 1232fps

speer reloading manual 13-

44-25-k (250 gr keith) max load of 2400 - 20grains for 1390fps

just curious as to why the huge difference in max loads for such similar bullets and which data should I trust??? I am not trying to load for max velocity but the starting load in the lyman handbook is the max in the speer manual so does anyone have any experience with either of these loads?

[HeavyMetal]

A lot of it depends on how they seated the boolit.

The 429421 and the RCBS 250-K are alomost indentical in size and design However if the RCBS guys loaded the round and crimped over the top band instead of in the crimping groove they will indeed raise pressures, and velocity, with less powder.

This is why it is important to determine OAL prior to load development and the reason you stay with that OAL as you increase powder charges.

This is way the manuals suggest a 10 to 15% reduction in listed powder charges, they have no control over your OAL and the subsequient depth of the boolit in the case.

Each gun is a rule unto itself. load for the gun not for the manual and it will be safer for all long term!

[Rocky Raab]

Different labs can have different test protocols, too.

The rule is to stay under the established maximum pressure. That seems pretty straight forward, right?

Lab A interprets that to mean not even one test round can exceed that number.

Lab B interprets it to mean that the average of all test shots doesn't exceed it.

Lab C interprets it as the average of all shots is below the number, and no single shot exceeds it by "x" psi.

Lab D holds the average below the limit and the standard deviation of all shots lies within "y" psi.

Clearly, all four labs might come up with a quite different "maximum" load - and still be able to say "these loads are withing published maximums."

And that's even before we consider different lots of components, different test guns, different pressure systems, and all the other differences, including weather!

[Hurricane]

Variance between guns, loads, or labs is normal when testing loads. There was an article in the Speer Reloading Manual #9 (now available at www.leverguns.com/articles/ballisticians.htm) named "Why Ballisticians Get Grey" that discusses this issue. It is common for two identical guns firing the same load on the same day to have different vuzzel velocities. One of the examples was with three 6" Colt Phythons chambered for 357 Magnum. They shot a 158 grain bullet at 1002, 1207, and 1251 fps. Nothing wrong with the guns, just the way it is. Testing the same gun with the same load will give you different reading on different days. Use the published data to get a general idea of what you can expect. Load to an appropriate velocity for what you want to do and then get to know your gun and load and don't worry about the exact fps of the bullet.

[UweJ]

Whenever I buy a can of powder I get a paper reloading manual from the powdercompany with it,(Alliant for instance).I found out that the loads they give here in germany differ greatly from the ones they give in the american manuals. Different government specs I believe.
But in your case I would start with the lower one and work my way up.In my case it was the load for a .45 acp. german loads end where american loadmanual starts. Remember from the same company,lol.

[SierraWhiskeyMC]

lyman cast bullet handbook 3rd edition(current)-

#429421 (245gr keith) max load of 2400 - 23.4 grains for 1232fps
(snip)
That's interesting. Keith's own load for that boolit was 22gr 2400, and he loaded pretty hot. Lyman's 45th edition reloading guide (1970) indicates 22gr* 2400 max (1295fps) for boolit #429244 (similar design but w/GC), starting load 18gr. (1088fps). Rem 2-1/2 primers were specified. Test loads were fired from a S&W Model 29 w/ 6-1/2" barrel.

* - designates compressed powder charge

[eta] I suggest that if you're loading for a S&W Model 29 to keep the velocities down. I've heard they'll loosen up if you shoot lots of high-vel loads through 'em.

The same handbook suggests IMR 4227, starting load 19gr (988fps) max 25gr* (1390) with the latter being the most accurate load out of 7 powders.

[jbc]

Thanks for the replies - to clarify some info the o.a.l. specified is 1.710 for both loads and the primer specified is a cci 300 for both loads but I don't have complete drawings for both boolits so I can't say if there is any significant difference in the amount of boolit inside the case but I would guess they are very similar. And i will say again for all those who preach about loading to max pressures that I don't plan to go near the max (although I am loading for a super redhawk that will digest them all day long) My biggest question was that I have heard that the old 2400 was weaker than the current manufacture and I know that lyman carries over their data from decades ago so I wonder if this may be the culprit? thanks again guys, JBC

[SierraWhiskeyMC]

(snip) My biggest question was that I have heard that the old 2400 was weaker than the current manufacture and I know that lyman carries over their data from decades ago so I wonder if this may be the culprit? thanks again guys, JBC

The data that I posted (22gr of 2400) was from Lyman's 45th edition of their reloading manual, vintage 1970.

You can get into trouble really quickly if you're loading at, or even near, maximum loads. Changing seating depth, primers, etc. can cause large pressure spikes, which can destroy your firearm (and maybe you too, in the process).

Always start at minimum loads, and work up slowly. If you change anything, start again from minimum loads.

Most of the time, there really isn't any point in using max loads. Your firearm's "sweet spot" will likely be found well below the max load level. Above that, you're wasting powder and wearing out your firearm before it's time.

[Bret4207]

Thanks for the replies - to clarify some info the o.a.l. specified is 1.710 for both loads and the primer specified is a cci 300 for both loads but I don't have complete drawings for both boolits so I can't say if there is any significant difference in the amount of boolit inside the case but I would guess they are very similar. And i will say again for all those who preach about loading to max pressures that I don't plan to go near the max (although I am loading for a super redhawk that will digest them all day long) My biggest question was that I have heard that the old 2400 was weaker than the current manufacture and I know that lyman carries over their data from decades ago so I wonder if this may be the culprit? thanks again guys, JBC

First, they aren't identical. Even two moulds carrying the same design designation can differ greatly, especially Lymans. All it take's is a slight difference to raise or lower pressure. Similar? Yes. The same? Not by a long shot.

The older 2400 isn't "weaker" . It's just a little different as far as burn rate. Good loading practice demands you treat each new can of powder as a NEW powder till you figure out if it's the "same" as the ones you used previously. In practice, many of us don't do that and get the occasional surprise.

[Doc Highwall]

The powder burning rate varies from lot to lot and the tolerance is IIRC +-5% . This is why when I have a new match gun built I buy enough powder, primers, and bullets from the same lots that when the components are about gone the barrel is shot also and I start over. I am just practicing lot control. This is why when I make up my batches of alloy I use a 14qt dutch oven so I can make up about 300 lbs at a time to eliminate variables, again lot control.

[jbc]

Thanks for the replies - to clarify some info the o.a.l. specified is 1.710 for both loads and the primer specified is a cci 300 for both loads but I don't have complete drawings for both boolits so I can't say if there is any significant difference in the amount of boolit inside the case but I would guess they are very similar. And i will say again for all those who preach about loading to max pressures that I don't plan to go near the max (although I am loading for a super redhawk that will digest them all day long) My biggest question was that I have heard that the old 2400 was weaker than the current manufacture and I know that lyman carries over their data from decades ago so I wonder if this may be the culprit? thanks again guys, JBC

just clarifying again for those who didn't read my whole post:roll: