Bolts Interchangeable?

[rocky321]

I read that the "flat" bolt is the more desirable than the round. Any truth to this, and if so, why is that? Also can the round be replaced with a flat??

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[browningautorifle]

That depends on many things. What serial range and manufacturer is your carbine? Some weren't even issued with flat I think. Others changed to round later. If you're changing, it SHOULD be headspaced to the gun.

[rocky321]

That depends on many things. What serial range and manufacturer is your carbine? Some weren't even issued with flat I think. Others changed to round later. If you're changing, it SHOULD be headspaced to the gun.

Headspaced, 10-4. I have a Plainfield. Very low serial #. D2xx. Right after the Korean War.

[emmagee1917]

The flat bolt was earlier and the only correct one on the early carbines. People trying to restore the early carbines need them. They were all blued , orig. , and any that have gone through a rebuild will be parked. Also people tend to like the looks of the flat bolt , and it looks more like a Garand with it , if that matters.
Round bolts are later , they produced a ton of them post war , most rebuilt carbines prob'ly have them , most lots of surplus liquidated in the 60s and 70s had them , mostly. Just supply and demand at work.
Outside of the above , the round was a product improvement , it's stronger , both will interchange as long as the headspace checks , WITH THE EXCEPTION of you firing a full auto M2. M2s must have the round bolt , the flats are not strong enough for the pounding. This is prob'ly why people call the round one the M2 bolt , even though it came out before the full auto adaptions.
Chris

[BrianQ]

I have a Plainfield. Very low serial #. D2xx. Right after the Korean War.

Plainfield carbines were in production from roughly 1962 to 1974 so it would have been made well after the Korean war.

[phil441]

A bunch of folks like the flat bolt because it has a more pleasing profile. I prefer 'em because they look like the bolts on the Garands I got to clean in College ROTC. Never got to shoot a Garand, but got a M1 index finger. No, not the M1 thumb many of us know, but a whole different story about that.
If it head spaces, it's good to go.

[Tired Retired]

Let me just point out one point about "round bolts" for any newbies reading this....

Everything mentioned above is true about USGI produced bolts... HOWEVER, if a bolt was manufactured specifically for a COMMERCIALLY produced carbine (i.e. Universal), it will not fit and should not be used in a USGI carbine! That also goes for its parts (firing pin, extractor, etc).

Someone correct me if I am wrong but the two exceptions to the above rule are the ejector assembly and the extractor PLUNGER (only) made by Ivers Johnson....

Just trying to keep it safe....

[rocky321]

Let me just point out one point about "round bolts" for any newbies reading this....

Everything mentioned above is true about USGI produced bolts... HOWEVER, if a bolt was manufactured specifically for a COMMERCIALLY produced carbine (i.e. Universal), it will not fit and should not be used in a USGI carbine! That also goes for its parts (firing pin, extractor, etc).

Someone correct me if I am wrong but the two exceptions to the above rule are the ejector assembly and the extractor PLUNGER (only) made by Ivers Johnson....

Just trying to keep it safe....

So than a Plainfield is considered commercially produced? Mine did make its way through the FAT factory in Italy. Unknown if for their military or Policia.

[imarangemaster]

See what markings are on the bolt. I had a Plainfield years ago that had all GI parts except receiver. I have heard that Plainfield did supply law enforcement and foreign military (Italy?) with Carbines in the 60s. Your FAT Plainfield would seem to support it. Does it have the FAT or a star stamped on the barrel under the handguard?

[Rustship]

Let me just point out one point about "round bolts" for any newbies reading this....

Everything mentioned above is true about USGI produced bolts... HOWEVER, if a bolt was manufactured specifically for a COMMERCIALLY produced carbine (i.e. Universal), it will not fit and should not be used in a USGI carbine! That also goes for its parts (firing pin, extractor, etc).

Someone correct me if I am wrong but the two exceptions to the above rule are the ejector assembly and the extractor PLUNGER (only) made by Ivers Johnson....

Just trying to keep it safe....

I have seen USGI extractor and Plunger, and ejector parts fit right in a Universal Bolt, and work.