Thread: 223 - unusual results

Originally Posted by Hermitage

So I went to the range today to test if the rubber tubing shown in Post #18 above effectively dampens out barrel vibrations/harmonics thus leading to smaller groups.

I used two .22LR rifles at a distance of 50 yards:
1 - Norinco JW-15s with suppressor and Bushnell AR 3-12x scope.
2 - Anschutz 1450 with suppressor and Bushnell AR 4.5-18x scope.

Attachment 257495

Attachment 257496

As both rifles already had the DIY bicycle tubing pressure on their fore-ends, I started the groups with the tubing on (right-hand target groups).

First was the JW-15s:
I fired a 10-round 'warm up' group with a hunting round - Fiocchi subsonic hollow point (these warm-ups are not on the target).
Then I proceeded to shoot the 15-round group on the top right of the target with the Fiocchi which came to 22.4mm/0.88" (after I took out the 2 flyers).
Next, I left the tubing pressure on and changed to Norma Tac-22, a mid-range target ammo. I didn't allow the barrel to cool down, so I did not fire a warm-up group. The 15-round Norma group second down on the right was 17.8mm/0.70".

I then removed the tubing pressure pad on the JW-15 leaving the barrel free-floating (the first 1 inch of the barrel was bedded along with action). I also let the barrel cool down.
I then fired a 10-round 'warm-up' and sighting group with Fiocchi (shot off target). Without the tubing pressure, it was firing high so I had to lower the elevation by 10 clicks (1/4 MOA clicks).

Now was the moment of truth...what effect would the tubing fore-end pressure have?
I shot the 15-round group on the top left with Fiocchi and it came out at 16.7mm/0.65" vs 22.4mm/0.88" for the tubing pressure pad! I was disappointed as my DIY tubing didn't decrease the group size and if it did dampen the barrel harmonics, the result-based logic shows it doesn't seem to matter!
I then shot the final JW-15 group with the Norma Tac-22 and free-floated barrel. The group measured 18mm/0.70" basically the same as the group with the tubing pressure (17.8mm/0.70").

I did the same procedure above with the Anschutz 1450.
Two groups with the tubing pressure using Fiocchi and Norma and two groups free floating.
Fiocchi free floating 21.3mm/0.83" vs Fiocchi with tubing pressure 23.4mm/0.92".
Norma free floating 17mm/0.66" vs Norma with tubing pressure 19.4mm/0.76".

Attachment 257497

Conclusion:
I have concluded from this experiment, that the whole barrel harmonics thing is very overblown. I tested this concept by making a biological thing (me the shooter) use the rifle. I mean, we're talking about precision, even if I'm the best shooter in the world I'm still a living thing, which means I'm the biggest variable involved. And the groups were so close that I'm sure it only comes down to the variable of the shooter in the end.
So as for 'harmonics'... pffff... myth busted in this DIY experiment using these two rifles.

The usual method is to place something between the bstock tip and barrel. Some come that way from the factory.

Originally Posted by Oldbloke

The usual method is to place something between the bstock tip and barrel. Some come that way from the factory.

You could go test this too and see what happens.

What is also interesting is the little polished JW15 just outshot the Anschutz. Best group at 16.7mm v 17mm, but four group average of 18.7mm versus 20.3mm for Annie.

Have seen that happen so many times!! Last one I polished tested out at 0.47" average over three smaller groups!

I'd say that the precision is unable to be determined as being any different between the 2. Without taking actual mean radius measurements from each rifle/ammunition combination and reasonably comparing - at a glance it appears that there is insufficient evidence to confidently declare any difference.

Which is still a win for the Norinco on value.

Originally Posted by csmiffy

Probably why the likes of Browning BOSS muzzle break/adjustable harmonic thingy didn't really survive. A lot of faffing about for marginal gains.
It maybe worked sometimes but not enough to be worth the hassle

My ears hurt just remembering those things.