Free Lunch

[schatzperson]

I do not shoot FP but was watching a friend shoot his free pistol the other day and a thought entered my head that lingers still.
The question I ask is this:
Surely, bullet dwell time is significant in FP;
In which case why the long barrels ?

One can make good use of a long sight base WITHOUT movement errors induced while the bullet moves through a barrel.
I am given to understand that dwell time is significant in AP, but maybe thats because of the slow speed.
However barrel dwell time is often quoted in other pistol shooting: Shoot a lethargic cycling S&W 52 and feel the "drag" !

Why is the case for Free Pistol different ?
What am I missing ?

[Rob]

Back in the 90's another shooter on the line had a Pardini with half the barrel cut off, and a long extended front sight to make up the "normal" long sight radius.
I think it was on of Don Nygord's modified pistols that he offered.

[rmca]

Why is the case for Free Pistol different ?
What am I missing ?

Accuracy. That's why you need the long barrel. Don´t forget that a final is score using decimals of a point.

[schatzperson]

....Scratching my head as to why a longer barrel on an FP makes it more accurate when it should make it potentially less because it increases dwell time ( more opportunity for slight movements to show up in longer periods).

The benefits of a longer sight base are obvious, maybe thats what was behind the Nygord modification mentioned by Rob.

Still in the dark.

[BenEnglishTX]

....Scratching my head as to why a longer barrel on an FP makes it more accurate...

Continue to scratch. All else being equal, shorter barrels are more accurate than longer barrels.

(Note: All else is never equal and the original question was about dwell time. After a detour, I'll get back to that.)

It seems counter-intuitive till you think it out. A barrel flexes during firing, while the bullet is still in the barrel. This usually hurts accuracy. Reducing barrel flex usually helps accuracy.

There are basically two ways to reduce that flex. The first is to make the barrel stiffer. There are several ways to accomplish that but the easiest one is to simply reduce the length. Take any tapered barrel and shorten it by half. A greater ratio of barrel diameter to barrel length is thus created making for a stiffer barrel that's usually more accurate. In thousands of cases back in the late 1970s and early 1980s, there were Remington 700 rifles that shot 2.5 MOA. Their owners wanted better, so they paid for re-barrelling. The cheap (sometimes free) discarded barrels were frequently cut in half, slapped onto an XP-100 pistol action, and the result was a flood of relatively inexpensive silhouette pistols that typically and easily shot sub-MOA groups using barrels that had been discarded as too inaccurate to be useful on a rifle.

There are other ways to make a barrel stiffer such as tensioning, the way certain benchrest rifles and interchangeable-barrel revolvers are built.

The second way to reduce the flex is to give up on removing it from the barrel system and instead seek to control it. Look up pictures of rimfire benchrest rifles. They all have funny-looking things screwed to the muzzles. Those are tuners. They put a weight beyond the muzzle, adjustable for distance from the muzzle. Shooters experiment with them and tune their rifles for best accuracy and particular batches of ammo. Even with the relatively thick barrels used by those rifles, barrel flex is a real phenomena that makes a huge difference in performance. They were initially scoffed at. Detractors loudly and often pronounced that the incredibly thick barrels of their .22LR rifles, when subject to the mild stress of a mere .22LR cartridge, could not possibly flex enough to create a measurable accuracy problem. They shut right up and adopted tuners posthaste (along with everyone else in that sport) as soon as they realized that you generally don't win without one.

I can hazard a guess or two why free pistol barrels are so long. First, they're already short enough that the flex may not be enough to make a difference. Second, they are held in the hand and no one who makes them considers that ultimate benchrest accuracy really makes any difference in final scores. Third, a long barrel is the easiest, simplest way to keep the sight radius long. Fourth, short-barrelled pistols with bloop tubes to increase sight radius are not necessarily more accurate. The bloop tubes would act as a tuner but tuners must be finely adjustable to be useful. Adjust them badly and it's quite easy to turn an incredibly accurate barrel into a random bullet-sprayer. Fifth, even if an adjustable tuner could be engineered that didn't make the pistol too nose-heavy, it would have to be adjusted. This requires nearly endless tinkering for a long time until you come to fully understand your barrel-tuner system. After that, it's still one more thing to worry about. I get the impression that free pistol shooters don't need anything more on their minds and that an infinitely adjustable tuner on the end of their barrel is something that would degrade performance through distraction even if it made the barrel more accurate.

Ultimately, though, I've seen lots of test targets from modern free pistols that were just one hole. I doubt you'll see too many people trying too hard to improve on the mechanical accuracy of such a system. It just doesn't seem necessary.

Someday, someone will experiment with an adjustable bloop tube on the end of a 4" barrel on a free pistol. They'll get the mechanics worked out, then screw on a non-adjustable version so they don't have to worry about it slipping adjustment. Then they'll take it out and start winning with it. When they do, everyone will start saying that they knew all along that dwell time in the barrel was a problem but it's only recently that a practical solution was devised. All the top-shelf shooters will convert to the fashionable new pistols with the bulbous muzzles and everybody will look back on those long, slender barrels of the past as quaint relics.

But until somebody starts winning with such equipment, nothing will change. I rather doubt it needs to. IMO, there's too much room for improvement in the humans holding the pistols for a tiny, incremental increase in mechanical accuracy to be measurable under match conditions. The major sports where such improvements are obviously pertinent to match results are sports where the pistols or rifles are fired from a steady rest.

As for dwell time, considered apart from the mechanical accuracy of the barrel, you may be on to something. There are examples of hand-held pistol sports with velocities below about 900fps where chopping barrels back to reduce dwell time seems to improve real-world match results. In those sports, however, (for a variety of reasons not pertinent here, including odd rules) no sight extensions are used. Thus the shorter sight radius that comes with the shorter barrel puts a practical limit on just how short the barrel can be. In my experience, a sight radius of less than about 8 inches begins to cause problems for those shooters.

The Nygord-modified pistol referenced up-thread by Rob sounds like it was on to something by addressing the dwell time issue. Unfortunately, "back in the 90s" I don't think anyone understood that hanging weight off the end of a barrel was a delicate business and those weights had to be properly adjusted. A badly-adjusted barrel extension/bloop tube/tuner can utterly destroy accuracy.

With all that the rimfire benchrest people have learned about tuners over the last 20 years, it's probably about time that some free pistol maker took that knowledge, applied it, and started experimenting with short-barrelled pistols. There may be something to it. I would not be surprised at all to find that a front sight extension that functioned as a proper tuner could improve mechanical accuracy AND that the shorter barrel in such a setup, by reducing in-barrel dwell time, would positively impact practical accuracy when you just stand up and shoot the thing.

Then again, unless someone starts winning with such a setup no one is going to care.

[schatzperson]

Interesting input Ben.
The center of my attention was really dwell time.

I agree that the accuracy limits of a modern FP (in a vice) has been reached, but the dwell penalty seems bizarre to me at least.

However I am sure someone is reading this and laughing their heads off at my naive assumptions.

Could it be a shorter barrel will require drastically different internal ballistics?
....ammo, twist rates etc.

It cant simply come down to a simple conservative approach to the pistol design.

[BenEnglishTX]

Interesting input Ben.

Thanks.

It cant simply come down to a simple conservative approach to the pistol design.

I wouldn't be too sure about that. My understanding is that adherence to tradition trumps technological progress in the International shooting games. If that weren't so, wouldn't all free pistols be fired by a switch held in the off hand? And wouldn't all rapid fire pistols have a bore line that roughly coincided with the center line of the radius bone of the forearm? Guns of both types have been designed...and promptly banned by the rules. In that sort of atmosphere, what pistol designer can find motivation to experiment with anything radical?

[schatzperson]

.....cant wait.......We could have a minimum barrel length restriction.
Ahh, the joys of bureaucracy.

[FredB]

The assumption people make when they worry about dwell time is that the muzzle was perfectly aimed at the instant the bullet started down the barrel. While that might possibly be true for prone rifle shooting, it is certainly not true for one-hand unsupported pistol shooting. Numerous excellent pistol shooters have advised us on TT and elsewhere, that if the shot is initiated when the aim is perfect, the result will be far from perfect. The pistol is constantly in motion; what you see is not what you get. That's why we use area aim and look at the sight alignment instead of the target. So, whatever happens during the miniscule dwell time differential between for example a 12" and a 6" barrel, is just as likely to help your shot as harm it. That's assuming, of course, that you employ reasonably good technique. But then if you don't have decent technique, dwell time is the least of your worries.

FredB

[schatzperson]

Perhaps less than excellent shots like myself worry that their dubious trigger technique will shift the shot out of their average holding area.

In my case at least, I improved significantly when I started to pay more attention to follow through.

My S&W 52 puts it in my face squarely.

[rmca]

You can look at it in two ways, adapt the pistol to the shooter or the shooter adapts to the pistol. Non being the way, a compromise is better.

If you shorten the barrel in a free pistol enough to make a significant difference in the bullet dwell time you will lose accuracy, in a bench rest your groups will be larger. To that large group you will add the shooters "humanity" or errors, and you get the final score.

Now, if you get the pistol as accurate as possible (longer barrels, tuners, etc. ) you will get a perfect score on a bench. To that you add the shooters "humanity" or errors and get the final score.

Everything else being equal (human error) guess what score will be highest.

[BenEnglishTX]

If you shorten the barrel in a free pistol enough to make a significant difference in the bullet dwell time you will lose accuracy, in a bench rest your groups will be larger.

It's not really germane to any practical discussion of free pistol shooting, but that statement is demonstrably wrong.

[rmca]

If you shorten the barrel in a free pistol enough to make a significant difference in the bullet dwell time you will lose accuracy, in a bench rest your groups will be larger.

It's not really germane to any practical discussion of free pistol shooting, but that statement is demonstrably wrong.

I'm sorry but I disagree.

Clamp a target pistol (ex. Pardini SP), a free pistol and a match rifle. Shoot them all at targets 50 meters away. Use whatever ammo you like in all three.

I've tested all three and I can tell you that the groups are wider on the target pistol, smaller on the free (some holes touching each other) and all touching in the rifle (almost a one hole).

They are all Olympic grade guns, and I'm only referring tho the best groups they did with different kinds of ammo.

Now to sum this up, the question asked was why the long barrels in free pistols. My answer was accuracy. Because otherwise the long barrel would be just dead weight.

[BenEnglishTX]

Clamp a target pistol (ex. Pardini SP), a free pistol and a match rifle. Shoot them all at targets 50 meters away.

As I said in my original explanation, all else must be equal. Of course three different barrels will shoot to three different accuracy standards.

None of this is germane to free pistol shooting where the pistol is held out in one hand. An ~10-inch barrel on a free pistol is sufficiently mechanically accurate that no one could benefit from any incremental accuracy improvement. It's also about the right length to give most shooters a sight radius they consider usable. As FredB has so eloquently explained, dwell time is a non-issue. Thus, I don't see any designs changing anytime soon.

However, for my .22LR pistols used in games that reach out to 100 meters (and sometimes 200 meters), where the pistol is rested and small improvements in accuracy become significant, I will continue to choose barrels shorter than the rules allow so that they will be relatively stiffer and, thus, more accurate.

[RobStubbs]

The assumption people make when they worry about dwell time is that the muzzle was perfectly aimed at the instant the bullet started down the barrel. While that might possibly be true for prone rifle shooting, it is certainly not true for one-hand unsupported pistol shooting. Numerous excellent pistol shooters have advised us on TT and elsewhere, that if the shot is initiated when the aim is perfect, the result will be far from perfect.<snip>
FredB

Fred,
You are mixing up two very different things. The muzzle should be pointed in the right direction when the bullet starts travelling - it's going where it's pointed. Shot initiation is a different thing which happens 0.3 seconds earlier. Obviously in that time many things can happen that can move the shot off target.

Rob.

[David M]

Coming up to the Sydney Olympics I made two new barrels for my Morini Free pistol, one 2" shorter (10") and one 2" longer (14") than standard.
Both were tested and shot for about 6 months with interesting results.
The longer barrel gave the best groups, most xring 10's, but any poor trigger shots it put out in the 7 ring and it was horrible to shoot in the wind.
The shorter barrel was easier to shoot, a lot less sight movement but gave less 10's but pulled a lot of 8's into the 9 ring.
On a calm days, if I was feeling well with had good trigger control and follow through the long barrel was best.
If the wind was up, feeling a bit shaky the short barrel was best.
If I had to shoot a final (tired and tense) - the short barrel.
In the end, I have shot the short barrel ever since and cut the long barrel down to 10" for my wifes gun.
Some years later I returned to the origional sight radius by putting on a rear sight extension similar to the short air pistol.
Now the best of both worlds, good sight radius, great in the wind.

[schatzperson]

If the longer barrels exhibit better accuracy, factors other than length might be at play. Perhaps the nature of the pressure impulse and twist rate have something to do with this.
I am saying this because there does not appear to be reason why longer is more accurate.

In flight, a spinning projectile of constant shape should NOT care where it originated from. It will care about External ballistics only.

Whatever Internal ballistics caused it to accelerate, spin and travel at particular rates, will cease to "exist" after it leaves the barrel.

Whatever measure dwell-time will actually have for a particular case ( skill level, ammo, gun etc), it appears to offer nothing but a potential disadvantage.

Once internal ballistics are evened out, a shorter, stiffer barrel, should offer an advantage to a pistol shooter.

[rmca]

None of this is germane to free pistol shooting where the pistol is held out in one hand. An ~10-inch barrel on a free pistol is sufficiently mechanically accurate that no one could benefit from any incremental accuracy improvement. It's also about the right length to give most shooters a sight radius they consider usable. As FredB has so eloquently explained, dwell time is a non-issue. Thus, I don't see any designs changing anytime soon.

The longer barrel gave the best groups, most xring 10's, but any poor trigger shots it put out in the 7 ring and it was horrible to shoot in the wind.
The shorter barrel was easier to shoot, a lot less sight movement but gave less 10's but pulled a lot of 8's into the 9 ring.

With this I do agree 100%

Whatever Internal ballistics caused it to accelerate, spin and travel at particular rates, will cease to "exist" after it leaves the barrel.

It´s exactly that that makes the difference. A longer barrel will shape and spin the projectile for longer, giving it time to "settle" in a certain speed and spin rate and thus leaving the barrel in a more controlled and consistent way every time. And that is one of the key points that makes a gun accurate.

[RobStubbs]

It´s exactly that that makes the difference. A longer barrel will shape and spin the projectile for longer, giving it time to "settle" in a certain speed and spin rate and thus leaving the barrel in a more controlled and consistent way every time. And that is one of the key points that makes a gun accurate.

And that's probably only noticeable rifle v pistol not 10, 12, 14cm as there's not enough difference.

That said a friend batch tested his morini (UK version) free pistol at the eley test range and that gave as good a group as most of the rifles tested at the time. Our free pistols have a longer than usual barrel because of our laws but I can't remember the actual length.

Rob.

[Gwhite]

I certainly don't recall seeing any tests groups, but I remember a photo of a Green electronic free pistol that had been cut way down. I think it had a 6 or 8 inch barrel.

All of the barrel vibration issues & interior ballistics will be heavily affected by the ammo. Because most ammo is designed for rifle length barrels, the exact results can really only be determined by actual testing with a rest. Lot to lot variation could also be significant. I suspect that ammo differences will be larger than a several inch change in barrel length.

Fortunately(?), all of my 9's ( and 8's, and 7's...) are my fault, so I don't really worry too much about whether my Morini shoots aspirin sized groups or dime sized groups.