Bullseye Powder discrepancy question

[Berettatn]

If you have the Hornady reloading manual, take a look at the .38 Special page for 125 gr. bullets. That's page 916. It shows that Bullseye powder can be loaded up to 5.3 gr. and that would be a +P load with a velocity of 950 fps. If you look at the Bullseye website, it shows that 4.8 gr of the same powder would be a +P load and the velocity would be 1021 fps. The bullet weights are the same but one is the Hornady bullet and the other is the Speer Gold Dot. Is it just me or is this a heck of a difference? While I am not completely new to reloading, I am a long way from an expert. I loaded some 125 gr. bullets with 4.5 gr. of Bullseye and did not notice them being anywhere near too hot for the S&W Model 15 that I was firing them in. I have loaded some with 5.0 gr. of Bullseye but now question whether those might be dangerous even though the Hornady book says they are not. So my question is for those with more experience reloading than I have.........what's the deal with the difference in information? I have emailed both Hornady and Alliant Powder and received no response.

[1gewehr]

It might be explained by the difference in the bearing surface of the two bullets. A bullet with more surface in contact with the barrel develops higher pressures than one with less metal in contact with the barrel. It may also have to do with the test firearm. Minor differences in rifling can lead to higher pressures.

Or, it could just be the amount of liability each company is willing to risk if your pistol has an issue.

That is why you should always start at least 20% below max and work up slowly.

[Guest Lester Weevils]

Ramshot's online downloadable load data pdf shows similar differences. For instance using ZIP powder (similar to W231), on 9mm loads--

124 gn Hornady XTP-- Max = 3.7 gn : Vel = 967

124 gn Rem Golder Saber-- Max = 4.6 gn : Vel = 1055

124 gn Speer Gold Dot-- Max = 4.2 gn : Vel = 979

125 gn Sierra JHP-- Max = 3.8 gn : Vel = 970

I tried to find equivalent comparisons in the Ramshot .38 data, but they don't have as many different brand same-weight bullets using the same powder. They show a ZIP max load for a 125 Sierra JHC at 5.3 gn Vel = 1098, and a Laser Cast FN at 4.9 gn Vel = 1112. But in that case it is a comparison against jacketed versus lead. Interesting that the lead gives similar velocity at a much lower load.

[Caster]

It took a time for me to get it in my thick head when I was younger, but charge weight for bullet weight is not precise. Quite the opposite across the board. Differing bullet shapes, lengths, diameters and on and on make enormous differences. That's why you work up from the bottom slowly.

One thing I would ask you first off is what kind of pistol are shooting? Reason being, if it's were say a Blackhawk, I'd roll my eyes and tell you to carry on. On the other hand if it were a Charter Arms or something closer to antiquity I'd say proceed with great caution.

[I_Like_Pie]

You are thinking right and are not out of line. Heck I still shake my head at some of the differences I have found.

There are differences in the test results from different manufacturers. Even the same manufacturer can show different pressures and loads during different years....I have 4 Lyman manuals spanding 20 years and all of them have different test results for many loads. Some of them may be measuring PSI, some of them may be measuring CUP. Some of them may be using a 2" test barrel ported for revolver simulation, and some of them may be using a 6" test barrel. (I am guessing that the test mule may be the big culprit)

Cannelure location on the bullet also makes a difference in initial pressure....deeper the bullet generally the higher the pressure spike. Heavy crimp vs. a light crimp make quite a difference also.

Powders can change formulation slightly over time. Unique and 2400 underwent a slight change in the mid 70s and again in the 90's

Caster is right on...pick one, reduce by 10% and work up to where it shoots a good group. Look for pressure signs but be warned that straight walled cartridges don't generally don't show signs until primers start flowing and it is WAY too hot.

That Model 15 can handle really hot loads...much hotter than what +P belts out around 20,000 psi....there is very little difference between it and a model 19 that digests 34,000 with no problems. 5.0 grains sounds like a good place to rest.

If you want to really push the edge on the best load you would have to go in sets of 10-20 increased in .2 grain increments until you have little spread in fps and good accuracy. Remember the best load isn't the fastest...it is the one in that "sweet spot" where accuracy, consistency, and bullet performance all line up to the same charge.

[Berettatn]

Thanks for the replies folks. As I mentioned, I started out with 4.5 gr. of Bullseye. That seemed very tame. Went to the range with 4.7 and that didn't seem any hotter so I went ahead and tried the 5.0 gr. No problems as the charge seemed just about right. I would say that whoever said something about liability for an overcharged round was about right. Lawyers and insurance companies are making the rules these days.

[Guest Lester Weevils]

I went many years wanting a chrony out of curiosity but too cheap to buy one.

After I got a chrony I don't hardly use it because I rarely adjust the recipes. Somebody constantly fiddling with loads might use one all the time.

However, after I finally got one have decided that it is a very useful if rarely used tool, and glad I finally spent the money. Maybe my reasoning is off, but I figure if I'm getting velocities about the same as the book, and my OAL is the same as the book, and the primers aren't melting, and they always go bang, then the odds are slim that I'm doing too awfully much wrong.

OTOH if the velocity happened to be a whole lot more than in the book, then it might be time to go back to the drawing board.

But I still stay pretty close to the book. Heavy bullets with fast powders are said to be able to generate excessive pressure even if the velocity isn't very high, so I don't get real creative.

Edited January 1, 2012 by Lester Weevils