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M1A/M14 chambers..

This is a discussion on M1A/M14 chambers.. within the The M14 forums, part of the M14 M1A Forum category; This may well be an effort to re-invent the wheel, but it has worked out well for me.. Sometime back, Banbam of: [Bamban's Barrel Barn ...


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Old April 18th, 2017, 08:18 AM   #1
Lifer
 
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M1A/M14 chambers..

This may well be an effort to re-invent the wheel, but it has worked out well for me..

Sometime back, Banbam of: [Bamban's Barrel Barn fame", sent me a barrel that by accident was short one full turn, that's 1/10 of an inch short of the normal 22" barrel. In addition to that it does not have the two feed cuts in the pre-chamber, usually present on M1, M14 style barrels.

Bamban finished the proper depth of the chamber to head space at 1.634", which is what I prefer. In doing so he used a secret chamber finishing reamer..

The finished product has a lead that is off the throat erosion gauge on the short side.. M118 and M852 ammunition will not allow the bolt to close.. That's not so bad, it will later as the throat advances. Shooting hand loads anyhow, why not seat the bullet deeper in the case, setting up the bullet seater die to find a depth that leaves the bullet .015" off the lands took awhile but the effort was worth the labor. ..

As it turned, out this is the best M1A/M14 type of rifle in terms of accuracy I have owned. Maybe this has been done before on purpose, if so, it is someting to look into for the Accuracy Shooters.

The .015" bullet seating dept was required to prevent too much chamber pressure , flattenig the primers big time, even with Ted Brown's load of 39.5 Imr 4895, which is outstanding.. My usual loads had been '006" off the lands, in addition to very flat primers the impact area threatened Texas. Art

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Old April 19th, 2017, 07:07 AM   #2
Lifer
 
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Maybe having the extra-short leade makes a difference, or it's just a 'good shooting' barrel.

But it sounds like that chamber wouldn't 'make spec' for any standard cartridge dimensions. That might be ok for a 'special order', but it should probably not be marked as '308 Win', maybe something such as '308 WIN AL special'.

How does it feed from the magazine in semi-auto w/o the feedramp notches?

Jay Kosta
Endwell NY USA

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Old April 19th, 2017, 07:24 AM   #3
Dodgin' The Reaper
 
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Most of the current SMK bullets and others with the same basic shape will generally have accuracy nodes about every .010 from contact out to as much as .100. VLD bullets on the other hand are much more difficult and tend to like very tight jumps. Most VLDs also require a different seating plunger to facilitate the narrow shape from the ogive toward the tip. Seating depth which changes the volume of the case will also have great effects on pressures and velocities out the tube. So many variables. So little time.
It's all fun Art and keeps us old dinosaurs busy.

Semper Fi
ArtB

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