Chambering a round

[Koda_]

to throw a wrench on the conversaiont my guess is a full length sized cartridge "might" rotate on bolt closure but a neck sized cartridge would "most likely" not....

 

[YZ-80]

It seems that the case/bullet would not rotate upon camming the bolt down unless there was enough friction between the bolt face and the head of the cartridge. In a jammed situation, the bullet encountering the lands and grooves might exceed the friction at the bolt face, in which case the cartridge would not move either. With control round feed, you have another variable with the claw in the extractor groove. Hell, I don't know. Now I'm going to be up until 3:00 AM, Dammit!

 

[PaLuke]

Thanks to everyone for the replies. After reading the replies I believe the round doesn't rotate when you close the bolt. If in some cases it did it wouldn't affect accuracy anyway. This was just something I didn't know if there even was a correct answer and did it even matter. Thanks again.

 

[DJ Morrison]

The easiest way to prove this would be to make a dummy round, place your borescope down the muzzle and watch as a round is loaded and the bolt cams over...

 

[ofbandg]

When you chamber a round the bullet isn't all the way home until the bolt handle is dropped because the bolt lugs are tapered. Normally the bullet isn't seated out so far that it will engage the rifling before the handle is dropped so it's free to turn with the bolt until it engages the rifling which should only happen in the last part of the rotation - and the first action of the engagement would result in the case being fully pushed back against the face of the bolt. If the bullet is seated out so far as to engage the rifling well before the bolt handle is completely down, whether the bullet turns in the case, against the rifling, or against the bolt face, would depend on the amount of friction in the various contacts. That is how I understand the process. If I am missing something please let me know.

 

[Lenny Foffa]

When I do load development there come a point when I am completely satisfied with that particular Load, I the begin to back off the OGIVE length of the completed rounds, to be able to allow them to work in the magazine well. I hate to have to do that, but I always fear I may need a quick second shot. So, When I begin to test loads with the OGIVE backed off 10/1000 thds or 15/1000 thds, I expect some of the accuracy I achieved with the Longer Length completed rounds, may begin to fall off slightly. I expect this because I am pulling the bullet further away from the lands and grooves. With my older mark V rifles sometimes it ,may go to 3/4 inch three sot groups, to a full inch or a tiny bit more. I'm Not happy with that, of course, but I feel it is still acceptable hunting accuracy. Note: The load I am testing now in the 270 Weatherby mag, has not changed at all, as I have shortened the COAL and OGIVE Length. This time ( Lucky) it did not seem to matter. I say this because as you make your loads to work the magazine of your rifle, The bullets may no longer be touching the Land and groves. So You need not worry about that. Below are two shots using the 130 Grn Ballistic tips at 100 yards at 3.300 ,and next to it are 3 shots fired at 300 yards with the COAL reduced by 30/1000 to 35/1000. So I'm guessing that making your bullet long enough to work in your magazine, which mean it is no longer touching the lands and grooves. and perhaps little to no accuracy loss. Interesting thread!!! Thanks for letting me play