Sine waves

[JFrank]

Sine waves

 

[gsardokla]

I must admit that you are way beyond a guy who grew up on a small farm on Dog Hollow Road

Just a country boy from S. Oklahoma who's been hunting since age of 6-7 and reloading since I was 15. Graduated from Ok. State and served in US Army, Ordnance corps. One of my mentors was a top dog (at one time) at the BRL in Aberdeen PG. Another mentor was a member the Hiroshima mission - he showed me his own personal pics of the mushroom cloud. He was a shooter, conventional munitions expert, and top marksman. While internal and external ballistics is interesting, my thing was terminal ballistics...and hunting, fishing, and shooting.

 

[AlNyhus]

Dusty has his flip flops but I'm a Croc's kinda' guy.

Fresh out of the chamber this morning and a rotational view.

Good shootin' -Al

 

[1911nut]

View attachment 1346042Sine waves

So what the hell are you doing with my girlfriend’s picture??

 

[Lucky Shooter]

I run .0015 on my 6PPC and BR, .0025 on my 30BR.

Jackie,

I've heard so much about neck clearances of .003 and up.

How do you determine the use of .0015 and .0025 ?

My gut thinking is that small clearances should be better
but so many others seem to like more.

A. Weldy

 

[Shooter13]

I'm not sure I buy the harmonics thing and I'm even skeptical about bolt lugs having anything to do with it but I'll admit to not having a better suggestion. It does seem to be more relative to neck thickness than anything but I have guns that produce it distinctively and others that don't. My winningest gun does not. Go figure.
If it shoots, I'm not sure any of this matters but I am curious. Been trying to figure the relevance of this for many years and bunches of bbls. I can't say that I've ever found anything conclusive.

Now aren't you the guy that sells tuners and that has everything to do with harmonics?? LOL Sorry just couldn't resist! See ya tomorrow at Boyle County!

 

[gunsandgunsmithing]

Now aren't you the guy that sells tuners and that has everything to do with harmonics?? LOL Sorry just couldn't resist! See ya tomorrow at Boyle County!

Yes but I still have a hard time believing barrel harmonics have much if anything to do with this particular sine wave. I've heard 2 lugs, 3 lugs, harmonics. Some have it, some don't. Clearance, thickness....I think I'll just accept it and go on with life.

 

[chop house]

Sine waves

so, is that a two lug action?

 

[AlNyhus]

Was sizing some 30BR cases this morning and grabbed this pic for anyone interested. -Al

 

[1911nut]

Was sizing some 30BR cases this morning and grabbed this pic for anyone interested. -Al

So what caused that? …..

 

[Dusty Stevens]

So what caused that? …..

The bolt lugs and a perfectly turned neck

 

[timeout]

So what caused that? …..

One would presume that sine waves was the cause. Is it good, bad, or indifferent? WTHK's? Way over my head.

 

[AlNyhus]

Briefly, these waves are noticeable when several factors come together. When you see these 'waves' on a competitive BR style gun, the neck clearance, powder charge and shoulder bump dots are pretty easy to connect. And it gives you a pretty good insight into the overall 'tune' of the gun from the standpoint of chamber pressure.

-Neck clearance. Less neck clearance (with no other changes) will have the waves further up the neck.
-Chamber pressure. The powder 'cleans up' as the pressure rises into the 'competitive' range. . When this starts to happen, you can normally see some subtle changes in the coloring of the inside of the case neck.

As the neck clearance gets over .004, the bottom will 'flatten' against the neck/shoulder junction. With more neck clearance, the 'flattening' stops and the entire neck will be covered in powder residue. If you have too much shoulder 'bump back', you can see the soot start extending below the neck/shoulder junction and on to the shoulder itself.

Live varmint stuff with snug neck clearances will also show the same traits...though it goes mostly unobserved by 99% of people working with them.

My 2 cents worth....... -Al