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head space or bolt face

 
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  #1  
Old 11-01-2008, 08:40 AM
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head space or bolt face

can some one explain head space to a green horn I am trying to make a vary accurate .06 all ready did tirger job and glass bed it up to sight ring about 2" of barrle it is a rem 721/700 were do U all think I should go next?
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  #2  
Old 11-01-2008, 04:27 PM
KRP KRP is offline
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Re: head space or bolt face

Head space is the measurement from the bolt face to the datum line on the shoulder of the cartridge.

How accurate is the rifle now and what would you like it to be? If you don't handload that is the place to start. My 721 '06 will shoot about 1.5 MOA, that's the best I've been able to get from it. It's 50 years old with who knows how many rounds through it and probably wasn't always given the best care. It still kills things though which is the important part. I've got another one that will get a completer workover one of these days(trued, new barrel, stock, trigger, etc.). What you do next really depends on what you want from the rifle and how much you would like to spend getting it.
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Old 11-01-2008, 04:50 PM
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Re: head space or bolt face

Head space measuring varies with the type of case. Bottle neck cases headspace on the shoulder. Rimmed cases on the rim. Belted cases headspace on the belt. Straight wall cases headspace on the mouth of the case. As with any rule there are exceptions. An example, 30-30s normally, being a rimmed case head spaces on the rim, but in the TC, it headspaces on the shoulder.

Most of the guns I've built were target guns and had rather tight chambers. I cut the chamber on a lathe until the bolt lacks about 1/8 of an inch of closing. Then by hand until it closes firmly.

I think if I was gonna build a straight hunting rifle, I'd loosen it up a bit but still just bearly accepting the Go Gage.
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Old 11-01-2008, 05:19 PM
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Re: head space or bolt face

Here is a tib bit from a rifle shooter magazine article by Patrick Sweeney.

"In simple terms, headspace is the dimension of the chamber of your rifle, the gap between the face of the bolt and the stopping surface for the cartridge. To be precise, it is the distance between the face of the bolt and the datum line, which is a circle of stated diameter, along the slope of the shoulder of the cartridge.


On a rimless cartridge such as the .308, the stopping surface is the shoulder. On a rimmed cartridge like the .30-30 or .303 British, the headspace is the gap for the rim. On a belted magnum, headspace is the gap for the belt. Since not every factory rifle or cartridge can be made to exact dimensions, with perhaps the best custom rifles being one exception, headspace is deemed to be correct if it is within a certain range."

Here is a link to the entire article. Measuring Headspace

If this is a factory rifle you could have the lugs lapped and the barrel cleaned and bore scoped for any unforseen problems.
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Old 11-02-2008, 07:20 AM
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Re: head space or bolt face

thanks for the info right now the moa is 1 3/4 at 89 y range finder didnt have room for a 100 yes it is a hunting rifle but here is my prob I am a mechanic deisel auto heavy equipment and so on ben doing it for 26 years so I got the mind set that any thing factory made CAN be tweaked to a lot better so would getting the bolt worked on or getting a costom bolt help me out accuracy. Trying to keep up to my buddy wiyh a 700 7mm rem mag I know but if I could pull off a 3" groop at 200 Y I would be happyer than a goffer in soft dirt I dont think that is to far out the relm thanks
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Old 11-02-2008, 04:07 PM
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Re: head space or bolt face

If 1 3/4" groups is the best it will do at 89 yards there is something probably wrong. The barrel may be bad, I would clean it to remove all the powder fouling and copper and then have it bore scoped. Check the crown do you see any dings or knicks, if so this could be part of the problem also. Try a different scope, you may have a scope that's not holding zero. Is the bedding stress free? Is the stock a plastic synthetic type? These types of stocks aren't usually worth even bedding as they flex so much. Are you shooting factory loads or hand loads. With some factory loads in a factory gun if you can get 1" at a hundred yards your doing OK. A new bolt more than likely isn't going to fix whatever is wrong, plus you would then have to have the headspace set. There is only so much tweaking you can do a factory rifle. Depending on what level of accuracy your looking for you might want to consider taking it to a reputable gunsmith to have it looked at. You'd be amazed at the difference puting a custom barrel on would do if done right.
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  #7  
Old 11-11-2008, 06:49 PM
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Re: head space or bolt face

think thats what I needed IT IS what it is. So a bolt aint going to do s#%t. Yes I can see a nick at the muzzle looking through it ( what about a 30 deg. or so bevel cut in it ) so if iam going to rebarle it what about going to 270 win or 7mm rem mag and yes I do use a good gun smith there in morris town MN do U know them? By the way just droped a doe with it yesterday it was a unfair shot 25 yards hart shot yyyyyyyyyyyyaaaaaaaaaaaaa
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