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-   -   2 groove or 4 groove (http://forums.thecmp.org/showthread.php?t=209012)

m60 tanker 04-18-2017 10:13 PM

2 groove or 4 groove
 
I just traded for two 2 groove barrels that are NOS barrels. The date on the barrels is 12/43. Which is better 2 or 4 groove.

gunny 04-18-2017 10:20 PM

There have been a lot of reports here and elsewhere that there is no accuracy degradation with 2 groove barrels.

tmark 04-18-2017 10:45 PM

I, too, have read that there is no appreciable difference in accuracy between a 2 and 4 grooved barrel.

But it is interesting why there are more 4 groove barrels than 2. The 2 groove barrels saved production time. So, why didn't the manufacturer stick with just making 2 groove barrels?????

bruce 04-18-2017 11:48 PM

Only my experience, but have fired a good many 03-A3 rifles with 2 and 4 groove barrels. With good ammunition nice condition 2 groove barrels produce on target results equal in every respect to what one can expect with 4 groove barrels. I currently have three 03-A3's, two sourced from the CMP and one that came from my brother. The CMP sourced rifles have 2 groove barrels. They will with good ammunition produce 10 round groups of 2 MOA or less. The one 4 groove barrel rifle will with equally good ammunition produce the same 2 MOA results on target. Back in 1990 I had a 03-A3 rifle w/ 2 groove barrel that would shoot MOA with good ammunition. I have a 03-A4 replica that will routinely produce MOA on target results using Winchester hunting ammo and handholds. With the one lot of HXP that I tried, it produced 1.25 MOA for 5 round strings. YMMV. Sincerely. bruce.

Bob S 04-19-2017 12:24 AM

Quote:

Originally Posted by tmark (Post 1593965)
I, too, have read that there is no appreciable difference in accuracy between a 2 and 4 grooved barrel.

But it is interesting why there are more 4 groove barrels than 2. The 2 groove barrels saved production time. So, why didn't the manufacturer stick with just making 2 groove barrels?????

When 2-groove barrels were authorized, many manufacturers were still rifling with scrape cutters ... a lengthy process that had to be repeated two or four times depending on the type of scape cutter. Some cutters could cut two grooves at a time, but still took many passes to finish one groove, or pair of grooves. Eliminating two of the grooves cut production time in half. For barrels that were "button", or broach rifled, there was no production advantage.

Respectfully, Bob S.

The Original Youngblood 04-19-2017 06:24 AM

Quote:

Originally Posted by m60 tanker (Post 1593945)
... Which is better 2 or 4 groove.

Neither.

Darreld Walton 04-19-2017 07:59 AM

In my own humble and meager experience...
 
I have seen the biggest improvements in accuracy between two, four, and six groove A3 barrels have more to do with ammunition and handload selection, and most importantly, stock condition and proper bedding.

Bigswedez 04-19-2017 08:48 AM

2 Groove barrel on an M1 is no good ! I bought one once .

edlmann 04-19-2017 11:25 AM

Quote:

Originally Posted by Bigswedez (Post 1594025)
2 Groove barrel on an M1 is no good ! I bought one once .

There's a reason for that: no arsenal or government contractor ever made a two groove Garand barrel. Those that do show up from time to time were made by a "gunsmith" grafting part of an 03A3 two groove barrel onto the stub of an old Garand barrel. Some of those might manage to shoot acceptably, but I'd be afraid that the same "gunsmith" might have manufactured a rewelded Garand receiver. In any case, a two groove Garand barrel is a good indicator to walk away.

Why would anyone do that? There was time when no Garand parts were generally available, either surplus or aftermarket, and the DCM was selling new-in-wrap 03A3 barrels for something like 50.

mtrippe 04-19-2017 10:57 PM

Here is a great article about 2-groove 1903A3s from the Remington Society of America:

http://www.remingtonsociety.org/remi...roove-rifling/


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