Shooting M1 with and without M3 flashhider

I was at the range yesterday and was shooting my M1 at the 100yd target. I had an original M3 flash-hider installed on the barrel. The groupings (5 shot) formed about a 5" group around the bull......I then removed the M3 flashider and proceeded to shot another 5 shot group without adjusting the sights..... the group was lower by about 6". I was getting dark so I could not try to repeat the same test but I'm fairly confident the results would have been the same.
Any thoughts as to why the grouping changed dramatically??

Your point of impact will also change on your M1 Rifle of M1 Carbine when attaching a bayonet, grenade launcher or flash hider because of
the vibration or harmonic waves that travel along the barrel each time it is fired will be different

"...the vibration or harmonic waves..." More about the weight on or off the barrel. Changes how the barreled action sits in the stock. Kind of odd it shoots lower without the FH though.

Browning was able to use the vibration or harmonic waves produced by the barrel when firing a cartridge to good use with their
factory BOSS attachment which could be adjusted to produce exceptional accuracy with a light barrel profile. Called the "sweet spot"
by the factory

Quote:

---

Originally Posted by Sunray

More about the weight on or off the barrel.

---

Not really. It's about harmonics. We did the same with the FN C1s when we shot with bayonets on. There were a few years there we did that, zeroed, qualification...everything. Because we expected them to be on in battle. Didn't really make the barrel sit anywhere else.

You wouldn't know about all that though, you weren't infantry. You didn't make a living with a rifle.

Quote:

---

Originally Posted by Sunray

Kind of odd it shoots lower without the FH though.

---

Kind of odd, you cancel out your own statement. Don't really know do you?

HMMM....

Thx Robert,
That helps explain a number of Non Ammo related issues I've had.
I was breaking in a new AR with my son over the course of a few months, getting to the range 1-2 times a week.
After finding a load it loved we thought we were done. Then while shooting the last mag of the day we get a string walking away from our POA.
After it cooled down we discovered the stock 'Bird cage' FH had come loose. When I cleaned it up I tightened the FH back down. Next trip out with same loads, same yardage, with us doing our usual take turns shooting 1 10rd mag each. We were half way back to POA. Not happy, Only thing I could think of was did I over tighten the FH ? Backed it off and twisted it down to just snug. Shots were back to where we had been before the issue.
I've been told that too tight can change POI. Another guy told me his shoots better without the FH, others say shoots better with FH.
I've learned to only change 1 thing at a time.... then check results.

We had three M1D rifles in my company and they were never fired with the flash hiders.

Back in the 1890's the Mannlicher 1895 Stutzen (carbine) used a special bayonet, it had an auxiliary front sight on top of the muzzle ring
which compensated for the change in point of impact caused by firing the Stutzen with a fixed bayonet

Quote:

---

Originally Posted by RCS

an auxiliary front sight on top of the muzzle ring

---

Yes, I can see in my mind's eye those bayonets...

Quote:

---

Originally Posted by RCS

Back in the 1890's the Mannlicher 1895 Stutzen (carbine) used a special bayonet, it had an auxiliary front sight on top of the muzzle ring
which compensated for the change in point of impact caused by firing the Stutzen with a fixed bayonet

---

Robert,
Was this a original set up?
I assume yes. I'm just surprised this type of technology has been around so long. I had no idea.....
If it went bang and you missed, we'd just fidget with the sights. If the sights couldn't adjust for the missed spot it was the old barrel or ammos fault.

When younger,
If I heard 'Harmotic wavelengths' it would have meant that Grandpa was drinking again and huffing thru his Harmonica in between his Pabst Blue Ribbons. So you just stayed out longer, because he couldn't play it worth a crap but he was too mean to tell so, especially when he was drinking :runaway:

A search on 'Flash Hiders effects on accuracy' turned up all kinds of show and tell demonstrations including Suppressors, Recoil checks and even Tuner breaks.
Interesting and pretty much a Science in its self.

Things really get screwy with any pencil-barrel rifle. An entire industry sprang-up for products to hang on barrels to improve the accuracy of the Mini14. I just accept the carbine and guns like the Mini for what they are. Hits anywhere on a coffee-can at 50-yards offhand over open sights.