Back in September of 2022, the mad scientists at MDT built a bolt action rifle chambered in .308 Winchester that had a six-foot long barrel made by screwing together two barrels. As you can imagine, that’s not an easy task because you have to make sure that the lands and grooves of the two barrels align and form one continuous rifling in the bore. Not easy, but apparently not impossible. They then cut that barrel in one-inch increments firing rounds after cutting every section and recording the ballistic data. The goal was to find out the influence of the barrel length on the muzzle velocity. Well, MDT has recently repeated the same experiment except now with a rimfire rifle chambered in .22LR and fitted with an almost four-foot barrel (46.5″) made by joining two 26″ barrels. Let’s take a look at the results of this experiment.
MDT @ TFB:
The muzzle velocity data that MDT engineers recorded is shown below.
Well, looks like the muzzle velocity drop due to friction of the projectile in the bore after the powder is completely burnt is not as drastic as many of us (myself included) would think, even for a cartridge like the .22LR.
Next is the standard deviation of the muzzle velocities in groups shot at different barrel lengths.
The standard deviation jump at the 26″ mark is pretty interesting.
Lastly, here is a picture showing the accuracy and precision of the groups at each tested barrel length.
I don’t see any difference between the extremes, but it’s interesting how at certain barrel lengths (44″, 36″) the groups are tighter.
To learn more about this MDT experiment, watch the following video.
It would be interesting to see the muzzle velocities of some overbore and magnum rifle cartridges (.22-250 Rem, 7mm Rem Mag, etc.) when fired in such extremely long barrels. Let us know what you think in the comments section.
Pictures by MDT Sporting Goods, www.mdttac.com
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