Locking bolt to lugs

[dtucker]

I am wondering that when you push your bolt forward as far as it will go how much more in length forward from the bolt face you are getting when you close the bolt and lock it up?

 

[Lapua40X]

I'm not a gunsmith and I'm a long way from an expert on the subject of rifles and their unique characteristics. But when I work on case length I remove the firing pin, close the bolt on a loaded round and expect the bolt to simply fall to the closed position. If the bolt closes that easily I would not expect there to be a camming action unless it was one of those old Winchester designed in the late 19th century. However, if there is a camming action I would expect it to vary from one action to the next. It's an interesting question and I believe, in search of the answer for my particular rifle, I might employ the use of a piece of Plastigauge and run a few tests (sans firing pin) to get the answer.

 

[dtucker]

Are you removing the firing pin because you are using a loaded round? I always use a empty case with light tension on the neck and a bullet in their.

 

[Lapua40X]

Are you removing the firing pin because you are using a loaded round? I always use a empty case with light tension on the neck and a bullet in their.

Yes .... kinda. I remove the firing pin to eliminate any pressure on the bolt so that it closes effortlessly. If I tried it with the firing pin in place the pressure on the firing pin spring would hold the bolt too firmly so that, regardless of how the round was conditioned, it would not give me the information I need with respect to knowing that head space is where it should be.
I have tried it with an unprimed resized empty case with bullet seated (and that does the job for routine sampling) but before a day on the range I want to be certain that every round is identical (or nearly so) and I check every round in the lot. Not to worry. Rifle is secure, on its rest and pointing down range to ensure safe handling.

 

[rocketron]

Dan
not 100% sure what your after on your question.

with no case in the chamber fore and aft bolt movement would be the gap between bolt handle and the action when it's closed.

with a case in the chamber movement would be dependent on how well headspace of the case matched the chamber headspace.

 

[dtucker]

Is what i am trying to say is how much further forward would the bolt face ( not bolt nose ) would move forward when you lock the bolt after pushing the bolt as far forward as it will go? Why would having a case in their matter, would it not always be the same?

 

[Dans40X]

The breech face,bolt nose & locking lugs are of 1 piece design/construction.
How would/could that change in linear dimension?

as rocketron stated-
Chamber headspace is the only deviation.

 

[BoydAllen]

When you close a bolt on an empty chamber, there is some fore and aft movement that is possible. The rearward motion is controlled by the bolts locking lugs, but the forward motion (in the case of a properly fitted barrel) is stopped by contact of the root of the bolt handle, on the rear bridge of the action, in the area below the primary extraction cam. When the bolt is cocked, the pull of the striker assembly on the trigger normally keeps the lugs against their abutments, but if the trigger is pulled, releasing the firing pin, this is no longer the case, and the bolt may be moved forward a small amount, till the root of the bolt handle makes contact. This is normal.

 

[Catfish]

If it is a rimmed case it would head space on the rim and if no rim is there it should have more slop then a round that head spaces on the shoulder. How much play would depend up the action and weather the rim is suported by the bolt face.

 

[dtucker]

I am not sure i am being clear or anyone understands what i am trying to say. With no case in the action, take your bolt and move it as far forward as you can. Now if somehow you could take a measurement referencing off something from the bolt face forward ( say to the end of barrel where bullet exits ) and then close the bolt on the empty chamber and now it is locked up...... would the bolt face be further forward and how much? I am just wondering when you lock up the bolt and receiver lugs together how much further forward would it be drawing the bolt face in than if you had the bolt pushed as far forward as you can before locking them up? This has nothing to do with head spacing, only some form of measurement on how much it would be.

 

[Eddie Harren]

Dan, With the bolt pushed in as far as it will go. put a cleaning rod down the barrel from the muzzle and rest it on the bolt face. Be careful of the crown. Make a mark on the rod flush with the end of the barrel. Close the bolt. Then check your mark. Again, before the expert gunsmiths jump my a$$, be careful of your crown.

 

[dtucker]

Doc, now you know what i am talking about and i like your way of doing it. I am going to stop at home depot and get me a couple wood dowl rods after i get off work. ;D

 

[BoydAllen]

If the action has some cock on close, then the bolt will advance as it is closed, pulled forward against the pull of the striker spring by the closing cams. There is also one somewhat obscure situation where this can happen for another reason. As I understand it, the rear of 1917 Enfield's locking lugs and their seats are slightly angled, and I seem to remember that the .22 version of the '03 is set up that way.

 

[sixshooter1948]

A dial indicator attached to the end of the barrel resting on your dowel rod should get u a very accurate measurement.