Bolt face - The Firearms Forum

Zednut · 10-01-2011, 03:35 PM

Question in regards to the machined depth on a 22 LR bolts' face. I measure a depth of .044-.050 on varios semi autos, obviously these need to be on the plus side of max rim thicknesses. However, several bolt action 22's Ive measured show a more shallow depth of .035-.038, which would generally be under the minimum thicknesses of rims. I would assume then that there is a small space between the breech face and the bolt face when the bolt is locked in, or else the rim would get crushed. Are bolt actions purposely built this way and is this advantageous for some reason?

Jim K · 10-01-2011, 07:20 PM

I suspect the semi-autos have more headspace to prevent slamfires. Some bolt .22's, including a Remington 511 I have, will fire if the bolt is closed hard due to the tight headspace (no, not the sear - the firing pin remains cocked). Ideally, tight headspace is good and increases uniformity and accuracy, but the makers don't want their semis going full auto.

Jim

JLA · 10-01-2011, 07:32 PM

I think Jim nailed it. It makes sense.

10-01-2011, 03:35 PM	#1
Zednut Member Join Date: Sep 2011 Posts: 11	Bolt face Question in regards to the machined depth on a 22 LR bolts' face. I measure a depth of .044-.050 on varios semi autos, obviously these need to be on the plus side of max rim thicknesses. However, several bolt action 22's Ive measured show a more shallow depth of .035-.038, which would generally be under the minimum thicknesses of rims. I would assume then that there is a small space between the breech face and the bolt face when the bolt is locked in, or else the rim would get crushed. Are bolt actions purposely built this way and is this advantageous for some reason? -->

10-01-2011, 07:20 PM	#2
Jim K Advanced Senior Member Join Date: Dec 2009 Posts: 6,408	Re: Bolt face I suspect the semi-autos have more headspace to prevent slamfires. Some bolt .22's, including a Remington 511 I have, will fire if the bolt is closed hard due to the tight headspace (no, not the sear - the firing pin remains cocked). Ideally, tight headspace is good and increases uniformity and accuracy, but the makers don't want their semis going full auto. Jim

10-01-2011, 07:32 PM	#3
JLA TFF Moderator/Host Join Date: Feb 2007 Location: Heart Of Texas Contributor Posts: 17,315	Re: Bolt face I think Jim nailed it. It makes sense. __________________ It takes 43 muscles to frown, 17 to smile, and 3 for proper trigger squeeze. The latest caliber or gear is no substitute for experience and skill. Rifles and cartridges don't make hits -- shooters do. Fact of life: After Monday and Tuesday, even the calendar says WTF!