?? RE: Powder amount/bullit weight/accuracy/ velocity.....

[Mikej]

I have a fair understanding of the relationship between:

Bullet weight to powder amount.
Presure to bullet weight and barrel length.
Velocity relating to bullet weight, presure, barrel length.
Faster vs slower powders.

Accuracy in relation to velocity is where I'm needing some input.

I'm dealing only with pistol ammo, .45acp .38sp and 9mm.

I've been going with only what's recomended in the Speer #14 book and a bit from the powder maker. I'm very hesitant to reduce a charge, and I don't see me going anywhere near the listed maximums in the recipes.

I made up some .45acp with 200jhp using two different powders, 20 of each with Titegroup and Unique. The Titegroup recipe seemed right with a slight increase over a 230gr slug, but the increase listed for Unique seemed awfully high to me so I reduced it by 2/10ths. They both seemed to kick pretty good but even from rest the accuracy seemed iffy. I shoot five rounds at a time when I'm shooting, the gun was a full size kimber 1911.

Now, I AM WELL AWARE of the standard disclaimers and accepted rules governing safe reloading. Would you reloaders continue to reduce charges, and what % of reduction would you stop at?

Would less velocity tend to contribute to better accuracy?

I also loaded 10 (needed a whole box of fifty ya' know) rounds of 200gr molly coated LSWC I had laying around. I shot those on a rest very last and 4 out of the 5 all tried to crowd into two holes at 50'!! The velocity listed in the book was cosiderably less than for the JHPs. I do understand that jacketed would need more "Push" to overcome friction in the barrel than lead.

Mike

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[Jamie6.5]

I have a fair understanding of the relationship between:

Bullet weight to powder amount.
Presure to bullet weight and barrel length.
Velocity relating to bullet weight, presure, barrel length.
Faster vs slower powders.

I notice you don't mention bearing surface/length of the bullet. Bearing surface has as much or more to do with pressures as weight does, as it contributes to pressure by adding friction in the barrel.
Two bullets of the same weight may have significantly different bearing lengths, and the one with the longer will almost always produce more pressure with a given load.

This is where a chronograph pays for itself. Used in conjunction with the accuracy from a rest, it will allow you to get somewhat of a handle on where you are, pressure-wise. Especially if you have literature that lists pressures as well as velocities.
When using velocity as an indicator of pressures, Use the load info from the manufacturer who's test equipment most closely approximates your barrel length.

Would less velocity tend to contribute to better accuracy?

Depending on the shooter, I would say yes. The more confident one is with their reloads/equipment the better the shooter they tend to be, but some people just tolerate high recoil better than others.

If you drop pressures low enough, FTEs will begin to occur. When approaching minimums, be sure to (safely) check for squibs, especially if you have an FTE/stovepipe.
Going back up from there until accuracy is where you want it, will give you an economical practice load, as long as you aren't hovering around the max charge by the time you get there. If that is the case, you have chosen a powder/bullet combo the gun doesn't like, or the gun needs work. (bushing, barrel, trigger etc.)
A chrony is the cheapest/best indicator of pressure, shy of strain gauge equipment, when approaching max charges in an auto-loader pistol.

Watch your primers for pressure signs too.

Good luck!

 

[orygun]

I'm not sure what you mean by "reducing the charge", or what you are reducing from. If you are reducing from the minimum listed for the given powder/bullet in the manual, I'd say you shouldn't. If you reduce the powder too much, you could be on the verge of sticking a bullet in the bore or at the least having a problem with powder position in the case causing erratic ignition. The erratic ignition could also cause terrible accuracy problems. Personally I start a little above the listed minimum powder charge when trying new things out.
If I wanted a "lighter" load, I'd change to a faster powder, such as Bullseye.
I've left out all of the bullet differences to check for, as it looks like Jamie has that covered for you!

 

[Mikej]

Thank you gentlmen.....I'm sitting on 1000 JHPs for my .45, just a tad less surface area than the 230s I was loading. I was looking for a little less recoil but still keeping accuracy with the 200s, rather than going to a 185. Recoil was the same as the 230s as far as I could tell with the recomended loads. I realize going too short on powder would give me an FTE, NO issue with the loads I used today.

I also am aware of too little powder in the case being a consideration. It sure doesn't take very much Titegroup in a .45 shell to make it work a full size all steel 1911, so I wouldn't reduce that one. If I were to reduce powder in the .45 I'd do it with the Unique rather that the Titegroup. But NOT without some concrete evidence that doing so would be safe.

I have been keeping a close eye on my shells for signs of too much pressure, not real sure what I'm looking for but I'm looking at most of them. I'm looking for deformed head stamps. The little dent they get from a point on the slide durring ejection is the same on my reloads as it is on factory loads!

I was hoping someone would chime in here that they had reduced, with a certain powder, a full grain and got good results, or something along those lines. Then I would have more room to play around, with more confidence. If I experiment, it's not going to be much at all off the tried and true recipes for sure!

And finally, those LSWC felt great, minmal recoil and quit accurate, that's what led me to think that slower is more accurate.

Mike

 

[deadshot2]

that's what led me to think that slower is more accurate.

This can frequently be the case. Finding that accurate load for YOUR firearm usually requires the time tested method of "working up a load" for a given bullet powder combination. It's complicated by the number of both that are available. Since you already have a large quantity of one bullet try making 5 round batches, starting at minimum and working to maximum in small increments. See which feels best and is most accurate. Ideally you'd have a "Machine Rest" for the tests so the human element is taken out.

Whatever you do, make sure that you make methodical changes and only one change at a time. Don't jump around with different powders and loads until you've tested one thoroughly.