Gunsmithing Headspace question- I'm gunsmithing ignorant!

[bm11]

Here's my dilemma-

I'm looking at ordering my replacement barrel for my AIAW. I contacted GA Precision about making me one, and they now recommend shipping your rifle to them so they can measure for headspace.

Turns out some of the rifles are out of AI's spec, to the tune of 0.003-0.006. If I order a barrel at my own peril without sending my rifle in (to avoid the shipping cost both ways and the couple of weeks of downtime- I shoot a lot,) and it turns out mine is off by 0.006, what happens then?

I know when I mount it I'll use go/no-go gauges. I just don't know much about headspace being off or the implications.

For what it's worth, my rifle with it's original barrel shoots consistent 0.5 moa groups with factory Gold Medal Match. If my headspace were off, would that be possible?

Please clue me in!

-Bob

 

[Quick Karl]

Re: Headspace question- I'm gunsmithing ignorant!

<span style="color: #000099">If your action/bolt CLOSES on a NO-GO gauge, you are technically OVER-spec (chamber too long/deep), but you can NOT determine HOW MUCH over-spec you are with a NO-GO gauge...

If your action/bolt does NOT CLOSE on a GO guage you are technically UNDER-spec (chamber too short/shallow), and you will not be able to chamber factory ammuntion.

Typically...</span>

 

[bohem]

Re: Headspace question- I'm gunsmithing ignorant!

If the headspace is large and you know this, you can account for it with judicious handloading practices. I've done it on purpose to test what happens and when you deal with it properly on the hand loads you still get fantastic results and not abuse the brass around the web and risk head separations.

ETA: Once you've shot the brass once in the rifle you can just neck size it for a while and not have any problems. You'll need a shoulder bump die when the time comes.

Really though, for the cost of shipping involved and the ability to have the rifle sent in and done right from the start then I'd just shoot something else for a few weeks and wait.

 

[Keith Johns]

Re: Headspace question- I'm gunsmithing ignorant!

If your question is whether or not to send the rifle away, do what GAP says.

And what about AI? If anything is out of spec, AI is who I'd be talking to.

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

Well, the other option is the option I went with.

AI is offering barrels now that Dave Tooley is making from Bartlein 5r blanks for them.

I ordered a barrel, my logic being that if I run into issues, AI made the rifle and also put their name on the barrel, so I they should fix the problem.

To clarify as well- Dave Tooley is a great name and AI themselves feel no need to send the rifle in. GA Precision's opinion was different and I respect that as well. I just went with AI because I felt that Dave Tooley's end product was comparable to GA Precisions, and if there were out of spec issues (AI is sure there won't be) than they should take care of me.

I was more posing this question to know what I should be looking for and what the implications were on headspace that might not be to GA Precisions specs but were to AI's spec.

What it boils down to is that if the headspace is a little off, most likely it is a bit on the loose side and accuracy will suffer a bit, yes? I understand the part about the reloading, however, I haven't been doing that just yet.

 

[GasLight]

Re: Headspace question- I'm gunsmithing ignorant!

odds are that the barrel that is currently on the rifle was headspaced to the action. That doesn't mean that any other barrel will headspace perfectly to the action. A typical no-go gauge is around .005-.006" over the go gauge. If the chamber on a barrel made to 'spec' was on the loose end, and you for some reason had an action that was on the tight end, you could end up with a chamber to bolt headspace that was over the .006" which would be over 'spec'. This means that if you use factory ammo, it would stretch further than 'spec' and if you reload, and FL size, it will over work the brass and cause pre-mature failure on the cases. There are ways around over-headspace, but the real answer if there is any question is to have the barrel made specific to the action. That is why GAP recommends that way. I am sure AI and Tooley are confident enough to do the job, and will warranty if there is an issue, but real world GA's way is the best way to match a barrel to an action.

DD

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

Thanks Dave. The thing is, one of the biggest selling points for me is that ALL AI's are made to the same exacting specs, so you could have 3 AW's in a room, mix and match the barrels, actions, and bolts, and they will be good to go. This is one of the reason's I bought the rifle over a custom 700 or something else. I'm hoping that it all goes together, I guess I just got a little paranoid with what GAP was telling me.

 

[Bacarrat]

Re: Headspace question- I'm gunsmithing ignorant!

You spent 5k+ on a rifle and are worried about shipping cost both ways to a smith? If you really do shoot a lot, get a couple of barrels turned when you have it at the gunsmiths.

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bacarrat</div><div class="ubbcode-body">You spent 5k+ on a rifle and are worried about shipping cost both ways to a smith? If you really do shoot a lot, get a couple of barrels turned when you have it at the gunsmiths. </div></div>They were willing to save the measurements actually, so I only need to send it in once.

Stand up people really! But still, it goes against my reason for buying the AI in the first place- user changeable barrels. They aren't supposed to require measurement and shipping, and therefore, my stubborn ass isn't going to do it, unless I'm unhappy with the performance of my new barrel.

 

[81sfo]

Re: Headspace question- I'm gunsmithing ignorant!

I ran into the same issue ,I bought an Aw for the same reason,to be able to switch barrels.I had to send out my rifle to have extra barrels made,which sucks if you like to be at the range a lot. I found a local gunsmith that gave me a two week turnaround.

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Forwardeyes</div><div class="ubbcode-body">I ran into the same issue ,I bought an Aw for the same reason,to be able to switch barrels.I had to send out my rifle to have extra barrels made,which sucks if you like to be at the range a lot. I found a local gunsmith that gave me a two week turnaround. </div></div>Do you know if your action was out of spec? Was AI not willing to sell you a barrel at the time?

 

[Immorteq]

Re: Headspace question- I'm gunsmithing ignorant!

If you're worried about headspace because your bolt closes on a no go gauge, you can slap a piece of electrical tape on the rear of the no go gauge, appropriately trimmed, in order to see how bad it is. I'm not saying shoot the gun if it doesn't close on the gauge with the tape. It's just another way to gauge how excessive your headspace is. Electrical tape is around .010 thick, I think. If the bolt closes you'll need to spend more money. If it doesn't close, you have other options.

 

[bohem]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Immorteq</div><div class="ubbcode-body">If you're worried about headspace because your bolt closes on a no go gauge, you can slap a piece of electrical tape on the rear of the no go gauge, appropriately trimmed, in order to see how bad it is. I'm not saying shoot the gun if it doesn't close on the gauge with the tape. It's just another way to gauge how excessive your headspace is. Electrical tape is around .010 thick, I think. If the bolt closes you'll need to spend more money. If it doesn't close, you have other options. </div></div>

Cigarette paper is 1/2 thou, regular 20lb paper is around 5 thou. Electrical tape is made of vinyl and squishes a little bit so it doesn't make great headspace gauge leaflet IMO. I use paper and I mic each slip that I am checking with so I get a very close check on them.

 

[Immorteq]

Re: Headspace question- I'm gunsmithing ignorant!

Agreed! If you don't have a mic or calipers to use more appropriate material of known thickness, a light touch and the electrical tape will get a decent ballpark for ya as well. I like the cig paper option!

 

[GasLight]

Re: Headspace question- I'm gunsmithing ignorant!

I doubt GAP is talking out of their ass. If they have seen actions vary in the range they are saying, I would tend to believe them. I understand why you bought the AI, and the appeal of it, it just must not be perfect from the factory the way they would like, otherwise GAP wouldn't see that kind of variation in actions. If you do go the pre-chambered route from AI and Tooley, I would just double check the headspace when you get it installed. What I use is a piece of feeler gauge that I cut into some 'roundish' pieces on the back of my go gauge. I have .002", .004", and .006" pieces cut. I can tell if my chamber is anywhere from .002" to .012" over the go-gauge with those pieces. They also last forever, so once you make a set you can use them for any rifle or barrel you want in the future, just need to be careful they are easy to lose LOL.

HTH

DD

 

[Craig Sandberg]

Re: Headspace question- I'm gunsmithing ignorant!

You can purchase sets of headspace gauges in .001 steps

 

[GasLight]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: craig s.</div><div class="ubbcode-body">You can purchase sets of headspace gauges in .001 steps</div></div>

That would get pretty expensive and without a full set you wouldn't know where you are anymore than with a single go-gauge, unless you got the perfect one for your chamber. The feeler gauge method is cheap and accurate. At least this is my opinion.

DD

 

[Craig Sandberg]

Re: Headspace question- I'm gunsmithing ignorant!

They are expensive, I took a rifle building class from Phil Lebow, he had several sets. I plan to get them for .308 and .223... they don't make sense unless you are really worried, have multiples in the same caliber, or plan to build rifles..

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

I feel comfortable using the feeler gauge method, thank you for that advice.

Here is my next question: I am going to assume that the barrel would fit within the acceptable ranges of go/no-go gauges, at that point, is there accuracy to be gained by a custom fit barrel to a different set of tolerances above and beyond that? By that I mean, is there a minimum amount of headspace that the rifle should be tuned to when the barrel is cut for maximum accuracy, or if the headspace is within range, is that the only concern?

Thanks for taking the time, I feel I am gaining a better understanding as we go.

 

[GasLight]

Re: Headspace question- I'm gunsmithing ignorant!

the tighter the chamber is around the brass will give for more accuracy to my understanding. This means that a chamber cut to minimum headspace will be more accurate than one with excess headspace all else being equal. The minimum headspace is the go-gauge. The top gunsmiths chamber a rifle so the bolt will just close on the go-gauge and will not close on anything larger than that.

Now, if you have a chamber that is excess to the go-gauge, you can still treat it like a minimum cut chamber by way of brass prep. It will require firing some rounds through it, but then instead of full length sizing, you only neck size and shoulder bump so the rounds will fit into the chamber nearly perfect. This has the same effect as a precise cut chamber, only take the fire-forming step first to get it.

The top smiths and minimum cut chambers seem to have exceptional accuracy with factory match grade rounds, and this is part of the reason why.

Dave

 

[GasLight]

Re: Headspace question- I'm gunsmithing ignorant!

Just need to add, this tight tolerance is all to a point of function. If you are shooting benchrest in a completely controlled environment, then you can have tighter chambers and actions, and not worry about feeding issues, as you will likely never shoot a factory round in the gun and will never feed from a magazine. For a true practical/tactical rifle, you need to have a little more room to allow for variances in ammo and conditions in the field.

 

[Craig Sandberg]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">Just need to add, this tight tolerance is all to a point of function. If you are shooting benchrest in a completely controlled environment, then you can have tighter chambers and actions, and not worry about feeding issues, as you will likely never shoot a factory round in the gun and will never feed from a magazine. For a true practical/tactical rifle, you need to have a little more room to allow for variances in ammo and conditions in the field. </div></div>

I shoot Factory ammo,(premium TAP or Federal Match) headspace on my rem 700 is half a thou, the only ammo I haven't been able to shoot has been from a Buddie that reloads, worked fine in his factory gun, but would not chamber (touch too long) in my gun. There are many factors in building an accurate rifle. Most of the high end tactical builders use very tight tolerances to achieve optimum performance with FACTORY ammo. If they didn't they would not be able to deliver that quarter minute accuracy that everyone wants... I would like to hear from some of you SWAT (or Military Snipers) guys, do they let you shoot your own reloads in hostage/sniping situations? (I honestly do not know) I know I am not an expert..... but I did sleep at Holiday Inn last night.

 

[GasLight]

Re: Headspace question- I'm gunsmithing ignorant!

I was quantifying my statement above about the tighter the better. And what I was stating has little to do with over all length of the chamber. A benchrest quality chamber will have minimum dimensions in the chamber diameter (this is built into the reamer, and has nothing to do with how far you push it into the barrel, which is what you are saying with the 1/2 thou headspace). They also will typically have a turn neck, all of these tighter tolerances are to eek out every last bit of accuracy from a cartridge. A tactical chamber will have more allowance for different ammunition as well as some dirt and the like, they do use tight tolerances to a point. This is also built into the reamer that they chose. I agree completely that there is a lot more that goes into a quality and accurate build than the chamber dimensions, however, you won't see a benchrest chamber in the hands of military or SWAT. They just don't work that well in the 'real world'. Also to clarify, a 1/4 MOA rifle would be absolutely unacceptable in most BR circles

 

[bohem]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">... Also to clarify, a 1/4 MOA rifle would be absolutely unacceptable in most BR circles

</div></div>


A number of years ago I watched a guy shoot a 6BR group at 300yd which he covered with a dime just barely. I had never seen such a group in my life, it measured in the high 1's.

His summary: "Barrel's on it's way out, I'll have to get this in to the shop soon"

I decided then and there I was never going to take a look into that obsession.

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

Thanks for clarifying Dave. To remain true to this build, this rifle can't have benchrest tolerances. This is a "tactical" rifle, and where I am no real world operator, I do shoot it off the ground, shoot in the rain, and shoot in the snow.

I'm not going to worry if my headspace ends up being a tiny bit on the long side, but I don't think it is.

Here is my logic-

All AW barrels, actions, and bolts are built to spec. As far as I know, AI is so specific in their action requirements that the barrel is always cut to the same spec and screwed on, and it works. Therefore, by that logic, my current barrel is of standard AI headspace cut. It shoots 1/2 moa with factory Gold Medal. Also- I tried a friends reloads, fireformed to his factory spec TRG. My bolt wouldn't close on them, meaning that my headspace is tighter than his, correct? And his is a TRG that shoots lights out as well.

So if A=B and B=C than A=C, if you follow me, haha. My logic is probably getting a bit abstract at this point, but hopefully you can follow me.

 

[GasLight]

Re: Headspace question- I'm gunsmithing ignorant!

I would still check the headspace on the new barrel, then you will know for certain. At the end of the day if it shoots how you want, what else is there?

DD

 

[GasLight]

Re: Headspace question- I'm gunsmithing ignorant!

To answer your question. If you action wasn't exactly the same as every other AI action, it was maybe .006" shorter, then someone custom fit the current barrel onto it, it would headspace exactly like it should, and you would have the same results you are saying now. Then if you order a barrel cut to spec, and it is just on the loose side of the tolerance scale, then you could end up with excess (in the length) headspace, which would be over .006" but would likely still not close on a field gauge.

Hope that helps a little more

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">I would still check the headspace on the new barrel, then you will know for certain. At the end of the day if it shoots how you want, what else is there?

DD </div></div>For certain dave. It'll be a few months or so before it comes in, but I'll certainly check the headspace.

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">To answer your question. If you action wasn't exactly the same as every other AI action, it was maybe .006" shorter, then someone custom fit the current barrel onto it, it would headspace exactly like it should, and you would have the same results you are saying now. Then if you order a barrel cut to spec, and it is just on the loose side of the tolerance scale, then you could end up with excess (in the length) headspace, which would be over .006" but would likely still not close on a field gauge.

Hope that helps a little more
</div></div>I understand! I don't believe my current barrel was cut to this specific action, because the way I understand it- that is not the way AI operates. The actions are supposed to be within a certain spec and the barrels are cut to a certain spec and they are put together. It does sound like from GA Precision that some might have made it out of the factory with actions a bit out of spec, but I would be surprised if AI actually fit their barrels to these out of spec rifles to bring them back in line. That would kind of be going against what they are all about.

 

[Craig Sandberg]

Re: Headspace question- I'm gunsmithing ignorant!

Thanks, I kind of figured it wasn't a bench rest gun when he wrote "AIAW". I guess back to the main question, checking the headspace would be the "safe" thing to do..

 

[81sfo]

Re: Headspace question- I'm gunsmithing ignorant!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bm11</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Forwardeyes</div><div class="ubbcode-body">I ran into the same issue ,I bought an Aw for the same reason,to be able to switch barrels.I had to send out my rifle to have extra barrels made,which sucks if you like to be at the range a lot. I found a local gunsmith that gave me a two week turnaround. </div></div>Do you know if your action was out of spec? Was AI not willing to sell you a barrel at the time?</div></div>
I remember my gunsmith comparing headspace to aother one of his customers headspace and he asked me.."isnt all AI rifles supposed to have same headspace?" I told him not anymore,lol.
No i wasnt going to get a barrel from AI i wanted a faster twist than 1-12 for my 308.

 

[bm11]

Re: Headspace question- I'm gunsmithing ignorant!

Gotcha. I was able to get a 1 in 10 barrel from them.