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  #1  
Old 09-22-2021, 11:18 AM
condor condor is offline
 
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Default Question about 2 groove barrel velocity

Was talking with my Dad yesterday about rifling. I mentioned that some 03s used 2-groove barrels. He mentioned a question about whether there's a velocity difference between 2-groove and more grooves.

Does anybody know if number of grooves affects muzzle velocity?
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  #2  
Old 09-22-2021, 12:08 PM
Tester19 Tester19 is offline
 
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Don't believe it does. No technical reason why it should. Seem to remember reading that the accuracy life of a two groove may be slightly less than a four or more, but I'm going from memory on that.
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Old 09-22-2021, 01:10 PM
ZvenoMan ZvenoMan is offline
 
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All the posts from those with firsthand experience in the 2-grooves indicate they do not have any measurable accuracy differences compared to the regular barrels.
I do recall hearing they may wear faster (as in over many thousands of rounds).
If I recall, some 1903A4s were built using the 2-groove barrels?
Like condor I can't imagine velocity is significantly affected.

The most unique item I recall is where some 2-groover barrels were converted to 4 groove by some entities (Bannerman? NatOrd?), and are pretty poorly done. Looking down the barrel will red flag this pretty quick, based on the photos I have seen.

JH
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Old 09-22-2021, 07:27 PM
cplnorton cplnorton is offline
 
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I have the Aberdeen testing grounds report which decided to switch to the 2 groove rifling.

It mostly just states that in all their testing the 2 groove was in everyway equal to the 4 groove rifling. It goes on to further state that there was negligible differences between the two and if any differences they were noticeable, they actually favored the 2 groove.

Ordnance approved their recommendation in a committee meeting that took place in Dec 1942 to switch to 2 groove on any production that would make sense, such as saving production time. The 2 groove rifling was approved for the M1 Garand, the M1903, and the M1917.
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  #5  
Old 09-22-2021, 07:47 PM
condor condor is offline
 
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Holy smokes.... great info, everyone!

Norton, do we know if there are any 2-groove M1 Service Rifle barrels in existence? Also - any mention of M1 Carbines being allows this measure?
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  #6  
Old 09-22-2021, 08:51 PM
Splashmonster18 Splashmonster18 is offline
 
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The only two groove rifle I have firsthand experience with is a SMLE, it had had a lot of rounds fired through it. It still shoots well but shows a decided preference for plain based bullets. Velocities seem to parallel 4 grove barrels I've shot.
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  #7  
Old 09-22-2021, 10:21 PM
Fenris_Bane Fenris_Bane is offline
 
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I believe the first rifle to use two groove rifling was in 1836. The English Brunswick rifle used two groove rifling and used banded round ball. The allowed the muzzle loader to increase the speed of loading because it did not require a patched ball or expanding bullet.
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  #8  
Old 09-22-2021, 10:59 PM
jimthompson502002 jimthompson502002 is offline
 
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There's probably a prototype 2-groove M1 Garand barrel SOMEWHERE, but they never got to production. Or more precisely: nothing got to the issue stage in numbers that anyone recorded.

There are cobblejobs from our great good friends at FedOrd, made by butting together and tack welding or otherwise combining the '03/03A3 tubes with the stub chamber ends of Garand barrels off condemned receivers. First one I ever saw had a date up front.

Those I would NOT trust, as with anything else with which FedOrd had more than a card-sorting "hand".

Last edited by jimthompson502002; 09-23-2021 at 02:17 PM.
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  #9  
Old 09-23-2021, 12:39 PM
blastit37 blastit37 is offline
 
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https://www.remingtonsociety.org/rem...roove-rifling/ This link has all the info on Remington's experience during WW 2. Its a long read but worth it.
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  #10  
Old 09-23-2021, 09:35 PM
TomD999 TomD999 is offline
 
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Hiya,


Not that my testing was all that scientific but I was looking to get velocity of my reloads for bullet drop so I went to the range with 2 loadings, both IMR4895 one was a 155g and the other 168.

I took a Danish return 4 mil SA with a "frosty" VAR barrel with 2+ on both TE/ME and a 3,9M Remington '03-A3 with a mirror like 2 groove with <1 on TE/ME.

For both loadings the '03-A3 was between 60 to 70 FPS higher MV. The '03-A3 outshot the M1 at 200 yards but not by much.

Tom
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