Inconsistent velocities with copper solids

[JohnO]

Aside from bullet size inconsistency have you considered that your barrel may not like those bullets? Have you tried your load in another gun?

[Clusterfrack]

The results from Cutting Edge copper solid 190gr lubed with Lee liquid Alox are encouraging. TLDR: no more low velocity fliers. My theory is that the lubricant prevents galling or wear products from causing transient increases in barrel friction. An added bonus to using the lacquer-like lubricant is it likely makes the loaded rounds more waterproof (I also use primer sealant).

(Use load data at your own risk. Work up to any load carefully.)
8.6g 800-X (slightly compressed load)
CCI LPM primers (based on previous tests, I expect similar velocity from non-magnum primers)
Starline brass
Bullets seated so the last ring is just visible above the rim. COL: 1.240"
Average: 1158fps (sd 11)





The bullets are highly uniform in dimension. Every one I measured was identical to 0.0005".

The front ring measures 0.4005"


The rest of the bullet rings measure 0.3990"


@JCL, @Cdub_NW, @GJM

[358156hp]

Have you considered a dry lubricant such as Boron Nitride Powder, perhaps rolled into the bullets bearing area?

[Clusterfrack]

Have you considered a dry lubricant such as Boron Nitride Powder, perhaps rolled into the bullets bearing area?

Good idea. I'm not familiar with that product, but the results I posted above were using Lee liquid Alox lubricant. You tumble the bullets in a small amount of Alox, and let dry on wax paper overnight.

[358156hp]

Good idea. I'm not familiar with that product, but the results I posted above were using Lee liquid Alox lubricant. You tumble the bullets in a small amount of Alox, and let dry on wax paper overnight.

Liquid alox picks up and retains dirt and other debris. I've used it in the past on cast bullets but I stopped with it and went back to std cast bullet lubes until powder coating took over for me. Champion rifle shooter David Tubb has been a proponent of HBN for a long time and even offers kits for embedding HBN into copper bullets. Here's a bit more information on it that can lead you to even more information if you choose to pursue it. Moly may work satisfactorily as well at the velocities involved.

https://www.6mmbr.com/bulletcoating.html

https://www.davidtubb.com/tubb-accur...ting?limit=100

[Exiledviking]

Clusterfrack, glad to see you may have got this figured out. Please do take any offense to me bringing this up. In order to measure single digit thousands of an inch differences, you have to use a micrometer. A set of calipers can vary up to a couple of thousands in the measurements.

So, to accurately measure the differences between bullets for your purpose you'd need a micrometer.

[Kriek]

I'm with Exiledviking on the measurement.

Another question from my side, seeing that adding a lube brings down variation.

On your original tests, did you fire fouling shots?

The blue bullets, as I gather, is a coated lead bullet. Some remnants of the coatting may still be in the barrel and lubes the copper a tad till it is scraped out.

Copper to Blue may not have such a big influence, but blue to copper will.

The copper jacketed bullets will also press remnants of the Blue's coating into the barrel, thus prolonging the effect. The mono copper (on these bullets with a sharper shoulder profiel) will scrape off the coating.

Even though the measuring instrument is not the best for the job, at least you can't see any variation with it. So, according to me and my experience, that small deviation (that you can not measure with the caliper) will not influence your velocities that much.

But I'm glad you made some headway.

And enjoy the rest of the testing.

Just a small contribution to your intended use:

A 150gr at 1450-1600fps gives a larger wound channel than a 200gr at 1100-1200fps and penetration difference is neglible enough as not to matter on buff and other large animals.


Sent from my BV8900 using Tapatalk

[Clusterfrack]

Clusterfrack, glad to see you may have got this figured out. Please do take any offense to me bringing this up. In order to measure single digit thousands of an inch differences, you have to use a micrometer. A set of calipers can vary up to a couple of thousands in the measurements.

So, to accurately measure the differences between bullets for your purpose you'd need a micrometer.

I believe that Starrett caliper is rated at +/- 0.0005.

[Clusterfrack]

I'm with Exiledviking on the measurement.

Another question from my side, seeing that adding a lube brings down variation.

On your original tests, did you fire fouling shots?

The blue bullets, as I gather, is a coated lead bullet. Some remnants of the coatting may still be in the barrel and lubes the copper a tad till it is scraped out.

Copper to Blue may not have such a big influence, but blue to copper will.

The copper jacketed bullets will also press remnants of the Blue's coating into the barrel, thus prolonging the effect. The mono copper (on these bullets with a sharper shoulder profiel) will scrape off the coating.

Even though the measuring instrument is not the best for the job, at least you can't see any variation with it. So, according to me and my experience, that small deviation (that you can not measure with the caliper) will not influence your velocities that much.

But I'm glad you made some headway.

And enjoy the rest of the testing.

Thanks. Interesting idea about fouling and BB coating lubricating. I don't think our testing sequence and results supports that. The low v fliers persisted in sessions with and without shooting Bluebullets prior. The frequency of those low values was ~1 in 5 shots, with a seemingly random pattern.

Just a small contribution to your intended use:

A 150gr at 1450-1600fps gives a larger wound channel than a 200gr at 1100-1200fps and penetration difference is neglible enough as not to matter on buff and other large animals.

This is an interesting topic. Based on my understanding (open to debate of course), I've settled on heavy wide meplat hard solid bullets. A CNS kill is what I'm aiming for if the worst happens and I'm forced to shoot a 1000lb brown bear through its thick, sloping skull. I'd like a CNS miss, but a body hit to have a long wound channel to maximize the chances of hitting something that slows the animal down.

@DocGKR, @Lost River, @GJM, @JCL

[Clusterfrack]

Liquid alox picks up and retains dirt and other debris. I've used it in the past on cast bullets but I stopped with it and went back to std cast bullet lubes until powder coating took over for me. Champion rifle shooter David Tubb has been a proponent of HBN for a long time and even offers kits for embedding HBN into copper bullets. Here's a bit more information on it that can lead you to even more information if you choose to pursue it. Moly may work satisfactorily as well at the velocities involved.

https://www.6mmbr.com/bulletcoating.html

https://www.davidtubb.com/tubb-accur...ting?limit=100

Very interesting. Thanks for sending this info. I'm at the "good enough" stage of this project, and don't want to order more bullets to run another series of tests. So I'm going with liquid Alox. Supposedly, dusting the exposed bullet after seating with graphite powder eliminates the stickiness of the Alox coating.