Science/Engineering/Technical forums

Here are pdfs of the Physics Today Articles, Doug.
I used SciHub to download them:
Keep safe,
Justin Fozzard

Thanks a bunch! My SciHub link broke...(this is normal, they have to move now and then) and I didn't think of it. I did ask Physics Today for permission - maybe a mistake, and they may insist I pull these down. So you guys know the drill...

When pondering an especially difficult problem - measuring the ion induced reactance and resonance width vs pressure in my cage geometry driven as an ion trap (relaxed mass spectrometer) - which looks like it'll be about like telling the difference between two flies flying aound in a room in a skyscraper - and 2 flies fighting, while only being able to jack up a corner of the building and put a scale under it (in the wind, of course) - I do something else distracting. As my friend and fellow programming magazine contributor Paul diLascia used to say "when I have a hard problem and can't find the approach that feels right, I mow my lawn - and then I know how to proceed". We used to joke that we had some very finely manicured lawns....

In this case, I'd been building up some parts for Swedish Mauser (6.5mmx55), and was having trouble getting what I thought of as the second best (certainly the 2nd most expensive) Douglas barrel to "shoot" - the real meaning of gun control - hit what you aim at, and only that. I had a collection of parts for this round laying around as I was kind of doing the "try everything" approach, thinking of possibly competing in class F long range shooting....health and other issues probably stopped that, but it'd be nice to have the good rifles for sale if nothing else.

I had a rusty old A&B barrel of heavy contour in the pile, rotting away. Well, that won't do, so I decided to thread and chamber it for my test harness action and give it a go, despite some rust also inside the bore. Not a lot - but I considered chopping off a couple inches at the end, which would have made it a bit shorter but still fine for benchresty kinds of uses (20 to 22" depending on how you measure).

The A&B barrel blanks were from MidwayUSA as their "economy" brand when I got them. I also got a Shilen - it's real good, and another A&B, lighter profile, pretty good, and a Kreiger - full bull, 5r fast twist, likely VERY Good (definitely very expensive...) but I've not machined that last yet - waiting for another action and a stock I don't mind really carving up for a barrel that's 1.4" diameter - end to end.
This one shoots the best of those yet tried. After that is the Shilen, and after that is the other A&B, and FAR FAR after that is the Douglas. Some of this is almost certainly my own variability and that of the stocks and actions (all of which I've worked over, but you know how it is). I'm going to keep messing with the one that stinks, just out of curiosity. It looks reasonable in the borescope...maybe some big void in the metal I can't see or some weird vibration mode? It's always good to learn things!


I didn't cut it yet (and may not!) - stay tuned for a long video about the whole process - how I do it on my affordable tools (no fancy CNC or flood pressure cooling during reaming and so on, just the home gamer stuff). But this one - like another cheap A&B I also have - shoots, and I'm frankly amazed, as this is with cast bullets, used brass...and the picture of the first 8 shots from it at 70 yards looks like this: For the first 3 shots I was aiming at the staple at the bottom (one shot had gone over the target before this). The second 5 - 3 in the same hole(!) were holding on the bull, on that shaky table with a bit of a pounding heart...I'll take it! There WILL be a rather long video at some point - if nothing else, I'm not done thinking and I need to justify the killer computer I built to ... edit videos --- (and play chess).
It's going to take some editing - It's about 35 3 minute shorts, 20 or so stills, and at that it's already condensed from 3 days worth of "spare time run". It's going to take some editing.

Somehow I get the idea you might beat the hell out of me at chess..

I just ordered a target barrel for my carry gun, making 4.6" instead of the 3.5" stock tube. Threaded, too, so I can borrow a can for giggles. If I need some custom milling or turning, now I know who to ask!

Looking forward to the video.

Dunno if I beat anyone at chess yet. Back in HS I made it to around 800 FIDE rating. No more...I did beat the computer once, the weakest engine set on the 2nd weakest strength..but it's still fun and relaxing to watch some of the streams out there. No politics to speak of - I'm developing fatigue watching idiocy all around. I'm actually picking chess back up to learn to lose. I was so Alpha back in the day that losing pissed me off horribly and made it and me not fun. I want to fix that personality flaw (or at least control it). I didn't hate whoever beat me, understand, but I was really hard on myself. There are good things that come from that, but not all are good.

4.5" or so was thought to be ideal by a few TX lawmen, I guess if you don't mind the size and weight. I own a range of sizes, but due to my small size, carry an ultralight snubby on my person (but a CZ 97b in the vehicle...). Not as relevant as it used to be as I'm becoming a real homebody these days. No real threats in this area that anyone knows about, but I of course have an Fn 5-7 under the footrest, and a S&W 6" .38 in the bedroom, because you gotta store them somewhere.
I've done some threading for cans for locals. One friend has a bolt .22lr and the result is actually better then the Hollywood myths. With subsonic ammo, all you hear is the firing pin strike and a thud from the target. It's quieter than his "silenced" pellet gun!

Video is waiting on a few good energy days - the stuff is all on the big computer, and of course, I'd like to generate a couple of clips of this thing in action. I wish I'd had a camera on it yesterday, instead of the chrono....
I went to "warm it back up" and verify my download for cast bullets - which was fine at 1710 fps - and gheesh, the shot went through the same group hole near the bull. I didn't believe it myself till I rode downrange for a closer inspection. Holy smokes!
Then I tried some almost full power loads to knock any burrs and rust out of the barrel...these were 120gr Nosler BT, 39 gr Varget, Win brass, CCI primer. The first power shots out of the thing made a 1" vertical string, all touching. They were going 2680 fps roughly - the first was faster, I guess because of some tight fit issue. This made a real mess in there - it's still soaking in various changes of copper solvent, as the bit of rust inside really scraped off a bunch of jacket material. Once that starts to look half reasonable it might be time for "shots of record" and final tuning - it's still not even bedded, though the barrel touches in a spot where I hadn't relieved enough stock to clear this profile. Interesting.

I think I'm developing a theory that at least part of why these cheaper tubes shoot so well is the alloy they're made of that machines like a dream. Perfect clean cuts if you do the setup correctly. Stainless steel alloys used in barrels machine more like chewing gum...burrs, material pushed instead of cut for light cut attempts, and so on. That's assuming you do know not to do things that work-harden it, whereupon you almost can't cut it anymore.
I can normally do stainless with good results for vacuum system kinds of things, but this requires another whole level of perfection compared to something I'm going to weld up anyway (yeah, I still can't do CF flanges - I don't have that diamond point tool).

I'm going to need to shoot some B roll stuff to set up the shots I have in the shop, explain a few things, and do some voice overs - the lathe kind of drowns me out, and I was too lazy (or safety conscious) to wear the lapel mic - mine isn't RF, it's wired. A little extra effort, but that's kind of the reason I'm doing this - I want to learn how to do it with a plan and kinda get the result to be like what was in my head to begin with, story wise. It will suck...I already know, but it'll suck less than any previous attempt of mine. There are of course plenty of good videos on YT of how people do this with unlimited cool tools, time and money, and I may link to them for those in that condition - that tiny fraction of us.

But you know how it is - I need good energy days both from the sun and from my medical conditions to coincide...I'll get there.

For those curious, this is actually the worst time of year for solar power. While it's not the solstice yet, the days are getting shorter and the sun lower - while it's still warm so the fridge and ventilation fans eat power, while the leaves are still on the trees and cause an extra couple hours of shade on the panels. The best time is Spring - still cool, no leaves, longer days. Assuming I'm able and get some help, a few trees are going down this Fall to help with that, and for the wood to burn later on. A lot of things are up in the air just now.

Belk's explanation of the billing was on target - I've gotten a few, not the ones I suspect will be really big, but they show that pattern. A huge number added up (with no codes unless you demand them of course). Then medicare's payment which is around 10% of that, then "adjustments" with no explanation for most of it, then my part, which is about another half of what Medicare paid. So a $3k bill becomes $200 from Medicare and $100 from me. I've not been battling those yet, as the one's I've gotten aren't unreasonable for the service I was rendered. It's funny how those "adjustments" magically appear when any insurance whatever is involved....From experience, if you don't have any - they stand rock hard on the huge bill and will take you to court over a number NO ONE ELSE PAYS EVER and claim it's legit. I've fought that and won, but most people wouldn't find it worth it.

Here ya go, Donovan. I just grabbed a few clips out of the >> 90 minutes worth I've already shot - with more shooting to come (in both senses).
While I also have DaVinci Resolve - with a vertical learning curve, I just did this in Shotcut, which amazingly just worked fine - even with two sources at different resolutions and frame rates - it just fixed things up. I did this at low resolution, the real one will be "good quality".
https://youtu.be/RmNKIjr6LG8

Thanks, Doug.

I know what you mean about machining SS, You can't take light cuts. Got to have enough "bite" so it throws a good chip and when drilling holes don't go light or the stuff will work harden.

I got my new target barrel for my handgun. It dropped in with no fitting required. I had India stones and polishing compound all ready to go, but no need. I'll shoot it tomorrow for a test flight.

If I don't post an update, it'll be because my hand will be compromised. That won't happen.

You bet, Bob. The usual 316 we all kind of hate is just as you describe. While I've not had the work-hardening issue so much with the barrel alloy - probably 416r - the burrs kill you. It's like those SS knives you can never get sharp, because a burr forms that won't go no matter what you do - it'll fold back and forth, and if you try to abrade it off, you wind up with something uneven - disaster for say, a crown. You can take fairly light cuts with sharp tools, but accurate takes really good machines that wouldn't make a chip on a "spring pass" - no flex. When tenths count...I dunno, I guess I'm just not good enough (or maybe I'm missing something else).

You'd better update us Donovan...I'll hunt you down and beat it outa ya.

I did some more work on that project. Last night I cold blued the barrel, just to make it look less nasty, it's not going to be a beauty queen, sealed it with Tung oil. Looks OK. Did some fiddly work on the stock and trigger guard and bedded it - now for the really hard part - Brownells says wait 2.5 days to shoot it. I also finished modifying and polishing the bolt face - it was originally for 8mm mauser, and the 6.5 swede has a slighly larger case head, so some things needed to change to make it feed smoothly. I also cut a 60 deg chamfer on the front of the chamber, and then used a dremel with a tiny buffing wheel to make a mirror smooth curve for easy feeding. Straight ammo seems to be helpful in shooting straight, and if it gets a lot of scraping and forcing going in, it doesn't stay straight...
Still assembling footage and stills for the eventual "how I build a neato rifle" video....I'm just at the point of looking at all those oddball camera generated filenames and making notes about what to use, what to ditch, what I need to just sit in from of a camera and say (some over some still pix), and so forth. Not ground shaking any of it, as far as I know, just a thing to do while I think about another problem.

I'll post some pics soon. Still waiting for the thread protector and OWB holster. ( I gained 20 pounds, not a bad thing at my age and infirmity.)

I test fired it today, and all the crap ammo I had went through it like shit through a goose. All I have to do is re-zero it. It shoots about 4" low at 35 yards.

It just looks ridiculous, but it's higher velocity, and promises to be very accurate. Considering..