Can bullet selection impact extreme spread of velocities?

[Zaydok Allen]

Greetings all. I recently tested some 10mm loads I worked up and collected some velocity data.

I was using twice shot Sig brass, CCI LP primers, a ladder workup of Accurate #9 with the top being a mildly warm load of 13.3 gr if I remember correctly, and pushing a 180 gr flat point plated bullet around 1250 fps on average.

1250 fps is listed on the box off bullets as the max velocity.

What puzzled me a bit was the extreme spread on velocities. One series was like 90 fps. I wasn't getting sooty brass at that point which seemed to indicate a good burn, accuracy was acceptable, and I had no malfunctions.

I guess I'm just wondering if pushing a plated bullet to max recommend velocities could cause the ES to climb.

Or are there just too many variables at play to answer this? I was thinking about trying this load in new brass to see how it works.

 

[ArchAngelCD]

I'm thinking there are too many variables to make any conclusions on the bullets and ES numbers but I'm far from being an expert. I will be watching this thread to see what the others have to say.

 

[troy fairweather]

try lp mag primers that may help and arch id right on

 

[Zaydok Allen]

I'm thinking there are too many variables to make any conclusions on the bullets and WE numbers but I'm far from being an expert. I will be watching this thread to see what the others have to say.

That's kind of what I was thinking but I just wondered if I was pushing that particular plated bullet a little too hard and if it's an obvious problem to a more experienced reloader.

The reason it's bothering me is it makes me concerned about my powder throw. I try to be very consistent with my technique and procedure, and charges seem to weigh out consistently, but I am using a progressive press, so variability is inherent.

It's plinking ammo so the ES isn't that important. But I'm trying to learn how to cut down the variables and improve the consistency of my ammo.

 

[ray15]

That's kind of what I was thinking but I just wondered if I was pushing that particular plated bullet a little too hard and if it's an obvious problem to a more experienced reloader.

What particular bullet is this? I'm assuming this is 10mm.

If it's the bullet reaching its limits I'd expect to see some evidence of plating failure. Is the bore clean? Can you recover a fired bullet? That said, it's entirely possible to create loads with a spread that high without any particular component problem (other than it's just not a good combination). I don't have 10mm experience but I'd try the same load with a 180gr. jacketed bullet and see if the behavior changes.

Do you have a LCT or single stage you could do the load development on? I weigh every charge when making up load development rounds as to not muddy the water.

 

[Zaydok Allen]

What particular bullet is this? I'm assuming this is 10mm.

If it's the bullet reaching its limits I'd expect to see some evidence of plating failure. Is the bore clean? Can you recover a fired bullet? That said, it's entirely possible to create loads with a spread that high without any particular component problem (other than it's just not a good combination). I don't have 10mm experience but I'd try the same load with a 180gr. jacketed bullet and see if the behavior changes.

Do you have a LCT or single stage you could do the load development on? I weigh every charge when making up load development rounds as to not muddy the water.

180 gr Berry's 0.40 cal bullet. Flat point. Used load data out of the latest Lee manual for plated bullets. Yep, 10mm loads.

The Bore looked clean to me and after cleaning the gun last night I saw no evidence of excessive platting failure.

I did look for a a fired bullet to recover, but was unable to recover any. They were buried deep in a dirt backstop.

Good thoughts on the jacketed bullets.

 

[murf]

as far back as i can remember, aa#9 has never required a magnum primer.

what is the c.o.l. on that load? varying the col can make a difference in es and accuracy.

how much crimp are you using? .001" is not enough for that load. .003" would be much better imo, but trying it out will tell.

luck,

murf

 

[Zaydok Allen]

what is the c.o.l. on that load?

1.260" per the load recipe

how much crimp are you using?

Tapper crimped to a case mouth diameter of 0.421.

 

[ArchAngelCD]

I'm not sure what the OAL has to do with high ES numbers. Also, the OAL published in the data doesn't matter in your load. It's valid for the bullet they used in the brass they used trimmed to the exact length they did and the barrel/gun they used. Your OAL should be what your gun and bullet used dictates.

 

[murf]

varying the c.o.l. will vary pressures. i fine-tune my load by varying the cartridge length .005" at a time. sometimes this can substantially change group size. there is a great deal of room to play with between max "plunk" length and min "won't feed" length. just don't get too short as pressures will get too high.

luck,

murf

 

[murf]

Tapper crimped to a case mouth diameter of 0.421.

what is the o.d. of the loaded round @ the case mouth (below the crimp)? if it is .418", you should be ok. the 10mm needs a good bullet/neck tension for the power level of that load you got.

murf