In order to participate in the GunBroker Member forums, you must be logged in with your GunBroker.com account. Click the sign-in button at the top right of the forums page to get connected.
.243/6mm.Rem/.244 Rem. interchageability
jaytee
Member Posts: 62 ✭✭
Can any of these be interchanged in a rifle? Now before you think I'm stupid or a bozo, I remmeber my cousin shooting off ammo in his .243. Seems you could shoot one in the other but not vice versa. Okay so maybe my cousin is a bozo![:D]
Comments
No one here thinks that you're stupid or a bozo simply because if you don't have an answer to a question, you have to ask in order to get the information you need.
The 6mm Remington and the .244 Remington are the same cartridge, 100%. The diffference is in the re-naming by Remington when they changed the twist rate of the rifles chambered for this cartridge.
The .243 Winchester is NOT interchangeable with the 6mm Remington or the former .244 Remington at all.
6mm Remington (244 Remington)
It has been said on more than one occasion that when Remington engineers were developing the .244, their primary objective was to come up with a high performance varmint cartridge and for this reason decided to go with a maximum bullet weight of 90 grains. This isn't exactly true. Instead, after extensive testing of many bullet weights, it was decided that optimum weights for the .257 Roberts case necked down to 6mm were 75 grains for varmints and 90 grains for deer. A rifling pitch rate of 1-12" proved to be the best compromise. The rest, as they say, is history.
For reasons that no one can explain (or prove), deer hunters decided that the .243 Winchester with its 10 more grains a bullet was a better choice. Or at least this is the traditional explanation. Possibly a factor even of greater influence was the rifles the two cartridges were available in. The .244 was offered in the Model 722, a rifle about as handsome as a fence post. The .243 was available in the sexy little Model 70 Featherweight. When it came to looks, there was no contest.
Around 1958, Remington started rifling all .244" caliber barrels with the 1-9" twist, but nobody seemed to notice. In 1962 when the new Model 700 rifle was introduced, the only 6mm cartridge it was available in was the .243 Winchester, but during the next year the .244's name changed to 6mm Remington and reintroduced in the Remington bolt action.
While Model 722 and 725 rifles with 1-12" twists will stabilize 100 and 105 grain round nose bullets, they usually prefer 95 grains or less when loaded with spitzers. Since Remington dropped the 90 grain 6mm factory load, those who hunt deer with the early 722's have no choice but to handload. Later .244 Remington rifles with 1-9" twist will handle the 100 grain factory load.
Source: Hodgdon Data Manual, 26th Edition
These drawings are not scaled to each other, compare the dimensions.
Best.
I hope to bring your attention to the shoulder dimension of the .243 and the 6mm/.244(as the latter have already been noted to be the same.) You will see that even though a .243 case is shorter than the 6mm/.244 case, it is not as small in diameter at the shoulder. Therefore, the .243 should not fit in a .244/6mm case. If indeed your cousin told you they could be interchangeable one way and not the other, that is not true. He could have possibly been playing the typical cousinly prank on you. In which case he would be the bozo.
What I am hearing here too, is that there may possibly be some mis-understanding of what is and what isn't. Make sure if you shoot with your cousin that you check each round and make sure they say Rem .244 or 6mm on the head. You can size a .243 into a .244/6mm Rem shoulder during reloading. After sizing that will fit into your chamber!!! Isolation of brass during reloading, and isolation of reloader as well help to curb this problem before someone gets hurt.