Bullet diameter after firing.....is it caused by lube or something else

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  • Last Post 06 August 2019
45 2.1 posted this 05 August 2019

A previous thread presents some interesting data. So, to not hijack that thread, this puzzle is here. It was presented by several people that bullets are sized down by the lube contained in the lube grooves while going down the barrel. Dialog and pictures were presented with the conclusion that the barrel groove diameter minus 0.003" to 0.005" was the diameter of recovered bullets. Using past posts as to what may have used indicated some from Lars lube, which is a high viscosity lube. If it's something else, then post what it was. Enough people use various lubes from several makers to determine it's properties. I test viscosity with a small pea sized ball of lube and play a butane pencil torch on it fairly briefly. It either shows melting and slump or it doesn't. I have several lubes given to me from Lars's lube and they seem to be high viscosity to me from testing them. My way would seem to be simplistic, but it gives repeatable results. The low viscosity lubes shoot very well for me while trials with the higher viscosity non melting lubes shoot larger groups. I make my own lube, but the only other like viscosity lube I've tested was Lyman Black Powder Gold (which I only use in old large caliber rifles). The question is, do high viscosity lubes reduce bullet diameter below the groove diameter as shown in the others threads post. I've tested the low viscosity lubes extensively through multiple year long testing under low to high temperature and associated weather conditions..... my results show no reduction in diameter. I have no problem shooting sub MOA groups in many rifles.... I also get panned for saying that. What do you guys get? Maybe this is the answer to "We aren't doing better"... Why?

Link removed. The link lead to a post on another forum that bashed the CBA and CBA members.  

CBA Webmaster

Maybe a little testing on this will help the accuracy problem stated by many here.

 

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Ross Smith posted this 06 August 2019

could not find the forum topic.  In plain english, the softer lubes work the best for you. I use White Label  red, where on your scale does it fit, if you happen to know that.

Thanks, Ross

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RicinYakima posted this 06 August 2019

You guys are talking two different things. Firing a bullet with 2 grains of Bullseye is not the same as firing it 2900 f/s. Two grains of Bullseye would not reach the malleability range of even pure lead. Run the same test with 7 grains of Bullseye.

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RicinYakima posted this 06 August 2019

Ross, it comes up if you copy and paste it onto the directory bar.

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45 2.1 posted this 06 August 2019

You guys are talking two different things. Firing a bullet with 2 grains of Bullseye is not the same as firing it 2900 f/s. Two grains of Bullseye would not reach the malleability range of even pure lead. Run the same test with 7 grains of Bullseye.

Ric, Larry said this over in the ogive shape thread :

"I have observed the smaller than groove diameter phenomenon at very low end pressures in 1000+/- fps loads up to the mentioned 2900 fps load at 50,000 psi.  That's actual measured psi btw, not questimated."

It seems it is sizing down bullets all over the pressure ranges for him. Joeb has his own ideas about testing for lube left in the bore. I've done my own tests also with pressures in the 10K to 42K range and haven't seen what he said. I do a lot of bullet recovery to see what happened too. I would like to find out what's happening.

 

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RicinYakima posted this 06 August 2019

I don't know either, that is why I am reading so closely. I haven't been doing any bullet catching in years since I don't have a good range or place to shoot except for the county park.

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Larry Gibson posted this 06 August 2019

Those "very low end pressures in 1000+/- fps loads " still had sufficient pressure to obturate the softer alloys used for those loads......just as RicinYakima points out.

Pushing a bullets, lubed or not, through bore is basically what we call "slugging the bore"  The results are not going to be the same as shooting the  bullet through the bore with a 20,000 psi load behind it. Or as in the bullets I recovered, 50,000 psi.

LMG

Concealment is not cover.........

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