accurizing the m1 carbine

8/14/2019 Accurizing the M1 Carbine

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72 PRECISION SHOOTING DECEMBER 2009

gue that the M1 Carbine and itsammunition was handier and con-

siderably lighter, but there was al-

ways the issue of its cartridge, in

reality nothing more than a mag-

num-class .30 caliber pistol car-

tridge. Ballistically unimpressive,

there would be numerous accounts

of its ineffectiveness against high-

ly motivated enemy soldiers.

All that being said, for pure fun

its hard to beat an M1 Carbine.

Over the years, my friends and I

have put holes through hundreds of

menacing cans peering from erod-

ed hillsides, perforated all kinds of

paper targets, and every now and

then an unlucky rabbit or two has

even gone into the pot at the end of

the day. One of the nice things

about the Carbine is that its light

recoil and non-menacing appear-

ance makes it a perfect center-fire

rifle introduction for the beginner,

especially women or their daugh-

ters.Here in the US, there has always

been a steady market for M1 Car-

bines and with import restrictions

put into place during the 90's the

supply has been fixed, with prices

rising accordingly.

Enter the Civilian Marksman-

BY DAN ARNOLD

As the product of a U.S. Army

Ordnance Department search for a

light rifle to replace the Model

1911A1 .45 caliber pistol, the .30

caliber M1 Carbine was to be the

most-produced, most-loved, and

most-hated rifle of World War II.Anecdotal evidence suggests that in

almost every theater of operations

there were GI's constantly swap-

ping for M1 Carbines, and seem-

ingly just as many swapping M1

Carbines for anything else to use

against the enemy. No one could ar-

The M1 Carbine was never thought of as a target rifle until the CMPcreated a match for it. Surprisingly, it is a capable weapon if properlyset up.


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ship Program: Large numbers of

M1 Carbines were loaned, to

various governments around the

world over the past 60 years and

because of their unique status, they

are not subject to import restric-tions. Consequently, CMP has

spent the past several years scour-

ing the globe for all of those loan-

ers. They want them back, and

they want to sell them to the shoot-

ing public.

Over the past three years or so,

M1 Carbines have been returned

from Italy, Austria, and Germany.

Their condition has been anywhere

from a solid good, to very

good. As would be expected, al-most all have been upgraded with

bayonet lugs and adjustable sights.

Some have been refinished and

stocks range from original World

War II-issue to World War II re-

placement, to post-war replace-

ments which may be U.S. or even

Italian-made.

In a move reminiscent of the

Gillette razor campaign, CMP has

not only provided a product for the

shooter but a venue in which to

shoot it, the CMP Games' M1 Car-

bine Match, which has further in-

creased demand for the little

carbines.

The course of fire differs slight-

ly from the other Games Matches,

the M1 Garand and 1903 Spring-

field / Vintage Rifle Matches. In-

stead of all firing being conducted

at 200 yards, the M1 Carbine

Match is held at the 100 yard-line

in recognition of its ballistic chal-

lenges. Competitors get 10 minutesfor 10 sighting shots and then five

minutes for 10 shots from the

prone position. Following that,

each shooter has 60 seconds to fire

10 shots each from the prone and

sitting positions and to finish the

match, the shooters fire 10 shots

from the standing position. The

M1 Carbine sling may be used as a

hasty sling, in all positions but

standing. As in all of the Games

Matches, ammunition is provided

and everyone gets a T-shirt at the

end of the match as well asachievement medals in recognition

of their scores.

I like the CMP Games Match-

es. They're fun, they're a relief

from several days of Camp Perry's

intense competition, and perhaps

best of all, they encourage shooters

to come out and participate in a

more relaxed venue than say, the

Presidents Match. It's also a good

excuse to take those old guns out

of the closet and see what they will

do.

Unfortunately, in the accuracy

department the M1 Carbine is

well-known for keeping ten rounds

inside a coffee can, at 100 yards.

That usually means the large five-

pounder, not the much smaller one-

pounder. So, that brings up the

question: Just what can we do

about the M1 Carbine's accuracy?

First, a brief history lesson: The

M1 Carbine, a Winchester design,

went from drawing board sketches

to working prototype in 13 days.

The U.S. Army's reaction was gen-

erally positive, but they requested

a more refined model which Win-

chester delivered roughly 30 days

later, on September 15, 1941. That

model, Winchester's number two,

is basically the same model that

would be manufactured until the

end of production in 1945.

Because Winchester was also

trying to get the M1 Garand intoproduction, contracts were let to a

variety of manufacturers, some of

whom had never produced a

firearm before. These contractors

varied from the automotive indus-

try (Inland Division of General

Motors) to typewriters (IBM) and

even included a juke box manufac-

turer (Rock Ola). In all, a total of

ten different manufacturers would

produce M1 Carbines. Additional-

ly, minor parts were sub-contract-

ed to various manufacturers during

the M1 Carbine production run, soeven an all-matching, M1 Car-

bine could potentially have parts

from a variety of manufacturers.

During and after the war, M1

Carbines were sent to arsenals for

repair and upgrading with ab-

solutely no regard for matching of

parts by manufacturer. I have seen

exactly one M1 Carbine that was

all-original. It was brought home

from the Pacific Theater by a

friend's father. All the others I have

examined have been a hodge-

podge of parts or an attempt to re-

store a rifle to its original

condition. The fact that M1 Car-

bines made up of unmatched parts

continue to function and exhibit

coffee-can accuracy is amazing in

itself, if you think about it. It is al-

so a testament to efficient mass-

production and the soundness of

Winchester's design.

As shooters, one thing that

works in our favor is that all U.S.

Military-produced ammunition for

the M1 Carbine was non-corrosive,

so the interior condition of most

barrels is quite good; so good in

fact, that I would not purchase any

carbine with a hint of frosting, or

corrosion in the bore. There are

just too many out there that have

nice, shiny bores.

Contrary to popular belief, gaug-

ing the muzzle doesn't seem to be a

reliable indicator of potential accu-racy. I have an Inland-produced ri-

fle that gauges a solid 3, with a

CMP muzzle gauge, yet it delivers

accuracy on par with other rifles

that gauge far better, so there must

be something else coming into

play.

A good friend passed on some


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into place, tighten the band, and

you're done.

This was an innovative way to

design a rifle. With this system, a

GI could strip his weapon with

nothing more than a cartridge rim,a coin, or a screwdriver, a welcome

feature in Italy's mud or Iwo Jima's

volcanic sand. Unfortunately, this

system wasn't conducive to the

best accuracy. With scores of prime

contractors, sub-contractors, and

egad, even sub-sub-contractors,

variations exist between receivers,

recoil plates, and barrel bands. To

top things off, three different types

of recoil plates and three different

styles of barrel band were pro-duced. Still, out of a total of six

carbines in my safe, I have yet to

see any parts that wouldn't inter-

change. That being said, neither

have I owned any rifles that I

would call particularly tight fitting

when I acquired them.

One of the joys of collecting old

rifles is their accessories. In the

case of the M1 Carbine, there is a

nifty technical manual from Febru-

ary of 1953 that goes into the

maintenance and rebuilding proce-

dures employed by the Army and

Air Force. If you wade through the

minutia, there are some interesting

tidbits to be gleaned from the man-

ual, such as accuracy standards.

For example, if a carbine could

keep five out of seven shots within

a 12-inch tall by sixteen-inch wide

target at 100 yards, it was deemed

acceptable. Wow! Suddenly a cof-

fee-can sized group sounds pretty

good, doesn't it? That same techni-cal manual also says in part, that

when the receiver engages the re-

coil plate, The action then

should be suspended by the recoil

plate with clearance under the re-

ceiver and barrel. If the barrel

and action were not suspended, the

recoil plate or stock was to be re-

placed or adjusted.

Unfortunately, there is no why,

or what if, in the technical manu-

al to explain the need for the barrel

and action to be suspended above

the stock, but I have a pretty goodidea what happens if that's not the

case. If the barrel simply falls into

the barrel channel at the front of the

stock, when the barrel band is tight-

ened the receiver is free to squirm

around in the recoil plate and the

barrel band becomes in effect, a

pivot point, which produces the

typical coffee-can group.

If, by luck or design, the barrel

has to be forced down into the bar-

rel channel, the locking tang en-gages the recoil plate much more

securely, eliminating some of the

action's free play and tightens

groups considerably. Keep in mind

though, the M1 Carbine was de-

signed to replace a pistol. In aver-

age hands, the average coffee-can

M1 Carbine will out-shoot the av-

erage 1911 pistol at 100 yards day-

in and day-out. While an

accurized, M1 Carbine won't win

PRECISION SHOOTING DECEMBER 2009 75

anecdotal evidence that pointed me

in the direction of a potential fix

for the carbine's accuracy. Like me,

he has succumbed to the lure of the

CMP store's rack upon rack of ri-

fles and as a result, owns more thanone M1 Carbine. Unlike me, he

seldom keeps any rifle that doesn't

shoot acceptably. I tend to keep a

rifle made by a specific manufac-

turer or a specific version based on

its overall condition until I find an

equal specimen that does group

well, and then sell the first one off

to another collector. Over the

course of running through several

carbines, my friend had noticed

that carbines requiring some down-

ward pressure on the barrel to force

it into the front of the stock and

slip the barrel band into place usu-

ally grouped better than those that

did not.

I doubt that barrel harmonics

are coming into play due to the car-

bine's 18-inch barrel, which in

most cases is encircled by a rather

tight-fitting barrel band and bayo-

net lug attachment at roughly its

mid-point. The cartridge the car-

bine is chambered for, the Caliber

.30, Carbine, Ball, M1, in military

parlance launches a 110-grain full

metal jacket bullet at an average

1,900 feet per second at slightly

less than 40,000 psi, hardly some-

thing we would consider as creat-

ing significant barrel whip.

Instead, I believe that we have

an issue of bedding. Or rather, lack

of bedding. The M1 Carbine's re-

ceiver has an upward-jutting lock-

ing tang that projects from the rearof the receiver. This locking tang

engages a groove in the recoil plate

in much the same way that the bar-

rels of many muzzle loading rifles

hook into a plate in the stock. Once

the locking tang is engaged, one

only has to lever the action down

into the stock, slip the barrel band

The standard post front sight andlate-WWII adjustable rear sighthave their limitations. Windageadjustments can be made

precisely. Elevation on the otherhand, is done by sliding theaperture in 100 yard increments.


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ing, the top of the recoil plate with

a brass hammer, thereby slightly

bending it and altering its fit to the

receiver. I have yet to try that

method, although it should work.

I'm just reluctant to whack away atexpensive parts that might be

marred or bent beyond repair in the

process.

A third way, if you have several

carbines on hand or a bin of spare

parts is to swap recoil plates until

one produces the desired result.

However, parts for the carbine are

climbing in price, with some man-

ufacturers' parts commanding pre-

mium prices. As a result,

purchasing several recoil platesseems to be a poor choice. Also, I

have done some parts swapping be-

tween my carbines and have had

limited success in altering the fit of

the action in the stock, so I don't

feel that the recoil plate is neces-

sarily the answer.

The stock itself seems to be the

culprit and the easiest to modify.

During World War Two, stocks

were made by 14 different manu-

facturers using three different types

of wood. Around the globe, re-

placement stocks have been made

for years, some out of rather exotic

woods like Malayan Kapur. Now,

there are even commercial manu-

facturers producing stocks for

those who want to restore their car-

bines to as-new condition. Every-

one's primary consideration

through the years has been that

everything fit together and the rifle

function as it should, rather than

the potential for accuracy. In in-specting different stocks, I have

found that the recoil plate mortise

depth varies noticeably.

By carefully removing wood

from the bottom of the recoil plate

mortise, the recoil plate's position

relative to the barrel channel is

lowered, which keeps the barrel

from bottoming out in the barrel

channel. In practice, I have found

that once the locking tang is en-

gaged in the recoil plate, the barrelshould float about one-half inch

above the bottom of the barrel

channel. Any more than that seems

to work no better and in some cas-

es actually causes parts to bind in

the stock, inhibiting functioning.

The amount of wood that needs

to be removed is very small. Thou-

sandths of an inch on the back of

the receiver translate to eighths of

an inch at the barrel, so taking your

time is paramount, as are multiple

trial-fittings. So far, this is the eas-

iest way that I have found to in-

crease accuracy. It also does

nothing to change a carbine's col-

lector value, and most importantly,

nothing has been done to preclude

shooting the carbine in the CMP's

M1 Carbine Match, which speci-

fies that no work other than careful

fitting of parts be done.

Using this method, the before

and after differences in group size

can be quite surprising. The mostextreme case was an Inland-pro-

duced carbine that my son had

picked out for himself. When I slid

the barrel band off the stock and re-

moved the hand guard, the barreled

action flopped in the stock like a

fish in the bottom of a boat. In that

state, five shots would not consis-

any benchrest matches, it is capable

of doing much, much better, even

reliably holding the ten-ring of the

SR-1 High Power target.

First though, a word about barrel

bands: In short, if you're interestedin the best accuracy, use the bayo-

net-lug, type three barrel band. It

has the most contact with the barrel

and the most secure method of

clamping to the stock. If the only

thing holding the carbine's metal

and wood together is a tang and re-

coil plate on one end and a barrel

band on the other, we want the best

and strongest barrel band there is.

Assuming that you're in posses-

sion of a loose-fitting M1 Carbine,there are four ways to alter the fit of

the barreled action into the stock.

The first and easiest way is to tight-

en the recoil plate screw. Some-

times, the recoil plate isn't fully

bottomed out in the stock recess

and no more than a quarter turn of

the screw will seat it deeply enough

in the stock to get the desired resis-

tance.

I recently found a very well-

written article about carbine accu-

racy on the CMP's website which

also points out the positive effects

of tightly securing the back of the

receiver and the recoil plate. In it,

the author recommends removing

the recoil plate and placing it up-

right on a vise flat, then wallop-

The screw-tightened barrel band is the only thing retaining the front ofthe barreled action in the stock. It should require slight pressure to

force the barrel down enough to slide the barrel band into place.


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PRECISION SHOOTING DECEMBER 2009 77

tently stay in the black bulls-eye at

100 yards. After I removed a small

amount of wood from the recoil

plate mortise and achieved some

degree of suspension, group size

settled down to 2 inches, whichwas due mainly to vertical string-

ing. Another Inland-produced car-

bine that gauged a 3 at the muzzle

and had very little suspension

could be counted on to put four

rounds into a 2.5-inch group and

sling a flier more than 3 inches out

from the middle of the group. Af-

ter a slight bit of fitting, group size

remained unchanged but the ten-

dency to produce fliers disap-

peared.One thing that can change dra-

matically after accurizing a carbine

is its zero, so fire a few shots at 25

yards to get a rough idea of where

it's shooting or put up a really big

target at the 100 yard-line. I use a

lot of repair centers for testing so I

can put up multiple targets side by

side and save all the walking back

and forth. In one case, a pre-accur-

ized carbine that had a good zero

put its first round into an adjacent

target after accurizing, a difference

of more than six inches.

The carbine's trigger is an area

that I haven't had to tune very

much. The worst of my carbine's

trigger difficulties could be traced

to hardened grunge or reparkerized

parts that had yet to wear down to

a bare metal surface. A good sol-

vent, some strategically placed

grease, and a little oil have usually

yielded a pull weight of five to six

pounds so long as I was dealingwith well-used parts. On parts that

have been re-parked, some quality

time with a stone and Dremel tool

have been in order. In other words,

take your time, and keep in mind

that the CMP rules stipulate a trig-

ger pull of not less than 4.5

pounds. As a comparison, the

The type three barrel band and bayonet lug, a necessity if you want toachieve any kind of accuracy with the carbine.

For best accuracy, there should be enough tension to float the barrel

above the bottom of the barrel channel before the barrel band is putinto place.

To achieve some degree of tension between the barreled action and thestock, wood needs to be carefully removed from the bottom of the recoil

plate mortise.


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Army's technical manual says that the carbine's trigger

pull should be more than 4.5 pounds, but less than 7

pounds, so in practice we shouldn't really have to slick

things up too much.

In use, the M1 Carbine trigger is a lot like a stock

AR-15 trigger, although being lighter by a few pounds:single-stage, short take-up, and lots of over-travel.

Hammer fall is slow, almost like a flintlock, but other

than being a little heavy as compared to my match ri-

fle, the carbine trigger isn't bad at all, certainly better

than a lot of off-the-rack M1's I've handled at CMP.

Reloading for the M1 Carbine is easy. With its al-

most straight case, carbide dies are the order of the

day, saving the drudgery of tumbling cases and remov-

ing media from primer pockets. As with everything re-lated to reloading, primers, cases, and powder are hard

to find right now. So far, a Sierra 110-grain bullet and

a charge of IMR 4227 lit by a Wolf small rifle-.223

Remington primer have performed satisfactorily and

have been relatively easy to find in my neck of the

woods. Of course, the ten-ring that we're concerned

with here is the NRA No. SR-1 reduction of the 200-

yard SR target for use at 100 yards, which has an X-

ring 1.35 inches in diameter and a 10-ring 3.35 inches

in diameter.

Can we really expect to hold the ten-ring at 100

yards? The answer is maybe. For this article I pulledfour carbines out of the safe to see what they would do,

firing two five-round groups with each carbine, using

my handloads. From a solid rest, the before-mentioned

Inland-produced carbines fired 2-inch and 2.5-inch

groups at 100 yards. An IBM-produced carbine fired

2.5-inch groups and a Rock-Ola-produced carbine had

a habit of putting four rounds into 2-inches along with

a flier that stretched group size almost to 3-inches. One

thing that is notable was each carbine's ability to put

at least three shots very close together, with the re-

maining two shots widening the group. This could be

shooter error, the coarseness of the sighting system, or

the inherent nature of the carbine design. Still, we are

within the 3.35-inch ten-ring, so I have no doubt that a

fairly average carbine that retains or is given some de-

gree of suspension during the accurizing process is

mechanically capable of keeping ten shots inside the

ten-ring.

The nature of the CMP's M1 Carbine match will

likely ensure that every shooter has a couple of 9's in

the prone slow-fire stage, though. With the flimsy cot-

ton sling attached to the side of the stock being usable

only as a hasty sling, precision shooting with any

carbine is going to be difficult, so cleans, are going

to be few and far between. However, precision shoot-ing with an as-issued rifle isn't about tiny group size

or shooting cleans, it's about doing your best within

the limits of the rifle and the ammunition issued that

day. And, it's also about having a good time with other

people, a notion that sometimes gets lost in the quest

for smaller groups and higher scores.


The recoil plate and the rear of the receiver as theywould be in the stock. The only thing to prevent up-down and side-to-side movement is tension in thesystem.

The C-shaped object is the recoil plate. Theupward jutting tang on the rear of the receiver isclearly visible. If these two are not tightly mated,accuracy will suffer.

accurizing the m1 carbine

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