Here's a post I copied from elsewhere that seems to make some interesting and thought provoking points....
I don't necessarily agree or disagree, but it does go into quite some detail.
I personally disagree with using a short barrel in an effort to move more quickly between PRS stages. I would still go with the longer barrel regardless of that suggestion for a more weight forward balance point.
All of what I'll say has culminated in what are the rifles we ship everyday, but having said this, I'm still learning, so the Vudoo's will continue to push the envelope.
What's most interesting about this are the number of those that told me years ago that I'd never get a 22LR to do what it's doing and no one would pay that much for a 22 rifle because, "it's just a 22!" So, again, thanks JB for being genuine and for supporting the 6X5 thread that has served as a huge data collection point that tracks the evolution of what's happening in rimfire performance.
-fast twist barrels: It wasn't long ago that no one really cared about the BC of the 40 grain projectile used by Lapua, Eley, etc., but now, Lapua publishes their BC (not sure if Eley does). This is because the community started stretching the legs of the 22LR and Lapua was the first to respond by teaming up with us prior to intro'ing the V-22 to market.
They developed two custom drag curves and made it available in the Lapua and Applied Ballistics apps so we could calculate firing solutions the same way we do for centerfire. Looking at the BC and doing the math to determine how much of it we're using by way of the twist rate, it became clear that out of the available .172, only .120-ish was being used with a 16 twist barrel.
Working the math backwards, the solution for using all the available BC in the 40 grain bullet was considerably faster, I was astounded and questioned whether I did it correctly....so, I did it again and came up with the same answer. So, we made a few barrels.
Two barrels were fit to two different actions but not at the same time.
The first barrel was 18" and ultimately, it shot like crap, which was discouraging.
Digging a little deeper and creating a few models to look at angular velocity vs muzzle velocity, etc., the conclusion was the barrel needed to be longer at this particular twist rate. I chambered up a barrel finished at 22" and tested initially at 50 yards.
The improvement over the 18" barrel was vast....I remember looking at the first five shot group and saying out loud, "son-of-a-#####!" After a few more groups, I handed the rifle off to Bob (whom is a sponsored shooter and does the testing based on our specific protocol) to shoot the strings of 500 round tests.
The first 500 rounds is broken down into 100, five shot groups at 50 yards. Just over 90% of the groups were beautifully round and measured just over the diameter of the bullet.
Amazing....but it got better. The groups at 100 were easily half the size of average groups from a 16 twist barrel (16 twist barrel was 18").
I continued to shoot this rifle for over a year and performed a silent test in September at the NRA World Championships (teamed with Lapua for the third consecutive year).
We had numerous targets, all steel plates at varying distances. I took numerous prototype rifles for the masses to shoot so I could observe third party testing without the shooters knowing what was new/different and I called wind on every target for three days in a row.
The groups from the fast twist barrel at distance were amazingly small and I had to call wind differently compared to the slower twist barrels. A week later, I handed the rifle off to Daniel Horner for a longer term test, but I had enough data to make more barrels ranging from my single digit favorite up to 15 twist. Bottom line is, the fast twist barrel is an absolute superstar at 22".
-barrel length: For the most part, barrel length is aesthetic when it comes to most rifle builds these days. Chassis systems with longer forends/foretubes typically need longer barrels to look right, etc.
The saving grace is, in Rimfire PRS and NRL22, this really doesn't matter with a 16 twist barrel at the distances targets are engaged.
A hit is a hit and the 16 twist barrels have done an excellent job and I consider these barrels to be the de-facto standard across all shooting disciplines.
Generally, I've advised many ordering Vudoo's that desire to compete in these games not go longer than 20". This is because they need to move with the rifle and get into and out of position quickly and there's a slight velocity advantage for the "hit-is-a-hit" approach to the COF.
Now, when I say what I'm about to say, please don't blow our phones up to change orders because I assure you with rifles in the build que, the barrel on your build sheet is exactly what you should go with.
In all the test rifles I build I use a 22" barrel that's cut and crowned without muzzle threads. The reason I do this is for consistency of data and to impose controls when comparing different barrel brands when we're asked if we'll consider using so and so barrel.
If/when I tell so and so barrel maker their barrel didn't pass protocols, it's not ambiguous or contaminated with "construed conventional wisdom" that's lurked around the rimfire world for years. I also don't go longer than 22" because I see velocities fall off and I need to have clear indications of lot differences in the ammo I test. The only time I'll go longer than 22" is for very specific performance criteria dictated by Benchrest, but that's not always a given.
Some barrels won't perform at the longer lengths but I've not seen the presence or lack of a choke point change that at all. Barrels are barrels, they're all different and they always will be regardless of who makes them and how they're rifled. There's more to share here, but I'll hold up here for now....
-button vs cut rifled barrels: So, this is where I've seen the most popcorn-worthy internet discussions and those believing a cut rifled barrel works for 22LR get blackballed in certain circles. "Hi, my name is Mike and I've been blackballed for believing a cut rifled barrel performs at a high level of consistency and accuracy when chambered in 22LR." And guess what....I don't care, because results are results and bs is bs.
Of course, this is where I'd hear (not on XX mind you), "if you look at the national results of who's winning what in the BR world, it's always a button barrel!" And I typically hear this in all capital letters on the internet or some old guy that smells like ginger snaps spraying spittle as he speaks very loudly.
I generally respond with the question, "do you ever wonder why more red cars get speeding tickets?" Very simple, there are more red cars on the road, so statistically speaking, it stands to reason that more would get pulled over.
Simple math will dictate, if you have 100 shooters in a BR match and 85 of them are using button barrels, how many of each will end up in the top 10? Couple this with the belief amongst various disciplines that it's just not possible for a cut rifled barrel to perform with rimfire and you'll quickly understand why there's 85 shooters in a 100 shooter match using button rifled barrels.
It really does boil down to what has been construed as conventional wisdom for a very long time.
So, let's dig into this button vs cut thing a little further but I'll do it in the form of questions....What tenon diameter do you typically see in receivers used for Benchrest? Given the starting diameter of the barrel blank, how much does the bore change while turning the tenon down to .750" with a button blank? How much does it change in a cut blank? Given what happens at the front of the chamber based on this change in bore, how many rounds does it take to clean up the anomaly in front of the chamber? Are you ever really able to clean up the anomaly? Does this condition change between cut rifled and button rifled barreling processes? What material do you see this happen most (provided it actually happens), chromoly or stainless steel? Now, taking all this into account, do you see this anomaly with a larger tenon diameter, say, 1.062? Last question: How many BR actions use a tenon diameter of 1.062? Answer these questions and you're pretty far down the road to understanding one of the reasons that it really doesn't matter when you compare apples to apples.
Taper Lapped Bore vs Non-Taper Lapped Bore: What a joke....when I've asked a few "big names" (one of whom wrote a book) why one would do this, I either never get an answer or I get the same regurgitated info commonly referred to in various circles.
One of whom I've come to respect was the only one to offer an honest, arrogant free answer and it was, "I don't know." From all the testing I've done, I can't come up with a single good reason that lapping a flaw into your bore is a good idea.
First, how do you control the outcome barrel to barrel? What do you do when you lap too much? How do you know you lapped too much? How do you know the lapping is concentric or some esophageal feature wasn't lapped into the bore?
Post lapping, what size bore are you starting with at the breech and how does this affect chambering? If there's anyone that gives an answer to any of these questions without using very expensive equipment they're not being honest with you.
Basically, taper lapping a bore is always a guess. And guess what else, I've seen terrible barrels from companies that are focused on quantities; their end result only needing to resemble a barrel, shoot really well.
Not for successive shots, but surprisingly well for some number of shots before having to sit for a while before they'll do something close to the same thing again. So, how does one tightly control the outcome from one barrel to the next, one rifle to the next, etc?
One simple answer that's not so simple....process control. Do the same thing the same way every time and the end result will be the same. Sounds simple enough, right? Well, it's not, hence the reason the belief that taper lapped bores make a big difference. I'll stop there....
Chambers: chambers are cool, love working on them, designing them, etc., and one of my favorite rimfire chambers is the Winchester 52D. The reason I'm not using it at Vudoo is because it was designed strictly for single shot use and while I'm ok with using it in my personal repeaters, it ain't cool if we ship a rifle that won't extract a loaded round.
So, I used the 52D as the basis of the 22LR RAVAGE chamber used at Vudoo. The RAVAGE chamber is a match chamber by it's very dimensions, being only slightly longer than the 52D chamber (the 52D is the shortest/tightest of all match chambers), but where it differs is the length and angle of the lead, which is how we're able to extract and eject a loaded round but still have the bullet where it needs to be for superior accuracy.
Based on a few recent discoveries, I'm working on a couple new chambers but this will take a while before I'm ready to share specific details. For the BR builds I'll be doing in the lab, I'll be using the 52D chamber while I test various barrels (Vudoo, Shilen and Muller). This is where I'll be calling on JBell for a bit of third party testing....
