4 replies to this topic

[ricochet]

Introduction:
A week or so back my nerf fabrication lifeline, my dremel, ceased to function properly. I got bit by the building/modification bug and had to find something to do that didn't require use of a dremel. So, after pondering some, I thought of revisiting the concept of rifling a nerf barrel. Is it even worth it and practical? Read through the following information to discover the answer. Just to mention, I have seen other threads similar to this, all with some flames. I am posting this in order to share my "experiment" and you can be the judge. On to the photos and stats:





You may be asking, "How was this fabricated?", and let me say it is rather simple. The video I used to guide the construction of the rifling is THIS video. I used the method of wrapping three paper strips (only 2 sheets thick) around a rod that is slightly smaller that 1/2" cpvc using the method in the video link. I then added super glue along each strip, quickly slid over the cpvc, and let it dry. Once it dried, I cut off the excess portions of the strips and slid off the cpvc. There you have it, the simple method of rifling some cpvc for your nerf gun, but is it worth it?

Testing:
The rotation applied to the dart is about 1 rotation every 5 inches traveled. I tested the rifled barrel in a nitefinder with a [k26] spring replacement, coupler mod, and 4" cpvc barrel. Nothing too big, just enough to use for testing. I tried the barrel with 2 different darts, one weighted (slug dart) and one not (slug dart without the washer). During testing with a weighted dart, it achieved a small distance increase of about 5-10 feet more than the smooth bore cpvc barrel of equal size. I also fired the dart (80-87 degrees)upward in order to observe whether a spin was actually applied to the dart. This can be observed using this method because of the fact that the dart slows down as it gets higher, thus showing the spin. It also returned to the ground with a spin as well. To verify the spin I then tested the barrel with an unweighted dart. Unweighted darts go haywire and fly in unpredicatable paths when fired from normal smooth barrels, so it was a good area to test. Upon firing with the rifled barrel, the shot went directly forward. Though it did tumble at the end of its flight due to the lack of weight, it was the opposite of the smooth bore. The normal smooth bore cpvc barrel made the dart fly in a sporadic manner, with no predictability. If you would like to see a demo of the test with the unweighted dart, the link is THIS. For all of the tests performed, only one dart was used (one unweighted, one weighted) to eliminate a source of error. What are your thoughts on this? Your feedback is appreciated!

Note: The link about how to rifle paper barrels is from a hobbyist who makes replica rifles out of paper. I am not encouraging the use of pyrotechnics or replication or reel steel rifles in nerf. Plus, fire and paper probably aren't that fantastic of an idea.

-Ricochet

Edited by ricochet, 15 April 2011 - 06:44 PM.

[Doom]

Your tests are inconclusive at best because you fail to provide basic statistical information like number of trials, standard deviation, etc. To be clear, simply firing a few shots with and without a rifled barrel and finding that the average range increased with rifling does not demonstrate anything. The range increase must be statistically significant.

Rifling almost certainly does not work to improve range for Nerf darts because the darts already are stable due to their weight distribution. See my analysis of previous rifling claims here: http://btrettel.nerf...com/archives/14

I am watching your video at the moment and I might edit in more comments. Edit: If I hear you correctly, you didn't measure anything. This is reason enough to completely dismiss your claim that rifling improves performance.

Edited by Doom, 15 April 2011 - 06:11 PM.

[ricochet]

Your tests are inconclusive at best because you fail to provide basic statistical information like number of trials, standard deviation, etc. To be clear, simply firing a few shots with and without a rifled barrel and finding that the average range increased with rifling does not demonstrate anything. The range increase must be statistically significant.

Rifling almost certainly does not work to improve range for Nerf darts because the darts already are stable due to their weight distribution. See my analysis of previous rifling claims here: http://btrettel.nerf...com/archives/14

I am watching your video at the moment and I might edit in more comments. Edit: If I hear you correctly, you didn't measure anything. This is reason enough to completely dismiss your claim that rifling improves performance.

You my friend are 100% correct about statistical data. This is merely observation based. Measurements weren't taken because of the type of testing done. Range is insignificant information to me. All I wanted to see was if the spin was possible and if it had any positive effect to the flight path. The entire aim I had in posting this was just to share my crude "experiment".

[Doom]

You do realize that observations are subject to statistical analysis?

Your method of testing is prone to cognitive biases like confirmation bias. Most people approaching the rifling issue want it to work. They will ignore the data when it doesn't work as they expect and credit rifling when it does work as they expect.

You haven't even established whether or not the darts spin. Note that your test for whether or not spin was imparted included no control group. I suggest getting an assistant to put on a random barrel and fire the gun. From the action of only the dart try to determine whether or not the barrel was rifled. (Edit: Also, to be clear, subjective measurements like this are best avoided.)

I suggest you try some further experiments and share the data.

Edited by Doom, 15 April 2011 - 08:48 PM.

[ricochet]

You do realize that observations are subject to statistical analysis?

Your method of testing is prone to cognitive biases like confirmation bias. Most people approaching the rifling issue want it to work. They will ignore when it doesn't work and credit rifling when it does work.

You haven't even established whether or not the darts spin. Note that your test for whether or not spin was imparted included no control group. I suggest getting an assistant to put on a random barrel and fire the gun. From the action of only the dart try to determine whether or not the barrel was rifled.

I suggest you try some further experiments and share the data.

Of course! Information brought to the table, like yours, is what helps design future experiments.