increasing headspace on newly installed factory original fixed shouldered barrel

[Revolting Peasant]

i have not found much information here on this topic or much of anywhere else for that matter so thought to pose this question.

recently i removed a very tired 308 win barrel off my howa 1500 to replace with another brand new fixed shoulder factory barrel i had in my safe of the same caliber. what i have found is the barrel fits perfectly as expected but the headspace is tight and needs to be increased by .005

i do not not want to mess with the bolt and decided to shim the barrel increasing headspace by .005 using one 18-8 ss steel arbor shim with 1'' id (perfect for od barrel thread diameter) and 1.5'' od. the receiver od at point of barrel action contact is 1.34''. i plan to shave down the excess shim for a better smoother fit.

in doing so i have now perfect headspace after tightening the barrel to 35-40 psi (i never tighten beyond that as i have found it excessive and unnecessary).

my question here since i have never shimmed a barrel before on a bolt action of this caliber and have yet to fire the newly changed rifle have i made a grievous mistake which will potentially give me trouble?

typically aftermarket barrels come with a barrel nut allowing fine adjustment for headspace. how is this setup using a barrel nut to adjust barrel depth into action any different than shimming a fixed shouldered barrel?

I've done and seen worse, that people said would never work. Meh. I don't see the big deal. Mathematics and metallurgy. Take a precision mic and gauges to most factory rifles and see way worse.
I prob would have done the same thing if I could find or make the proper shim.
Go to almost any reloading thread and see a lot more questionable practices.
How does it shoot?

 

[aschler]

I agree with Darryle. If the thickness of the recoil used is a determining factor, it should be information that needs to be factored in. But that's just me.

Of course the thickness should be factored in, it is the primary design criteria.

Several people stated they used different thickness recoil lugs to fix the same problem and the variance between recoil lugs was twice the thickness of the shim in question; no one questioned those people.

 

[FEENIX]

Of course the thickness should be factored in, it is the primary design criteria.

Several people stated they used different thickness recoil lugs to fix the same problem and the variance between recoil lugs was twice the thickness of the shim in question; no one questioned those people.

If it works for them and they are willing and able to accept the pre-fit being out of spec, I say more power to them. Again, this is one of the reasons I use Savage actions for my DIY projects; its floating bolt head + barrel nut is more forgiving.

 

[Darryle]

Theoritically, yes; do you think that shim will result in any more misalignment in the OP's rifle or 99.999% of the other factory produced rifles out there? I'm putting a lot more faith in the flatness of the shim.

Who makes a shim that is 26mm id that is .005" thick and has an outside od of 30mm?

I would agree, but I looked for a single round shim and could not find one, maybe your Googlefu is better than mine

 

[JD284win]

Of course the thickness should be factored in, it is the primary design criteria.

Several people stated they used different thickness recoil lugs to fix the same problem and the variance between recoil lugs was twice the thickness of the shim in question; no one questioned those people.

A recoil lug is a component of a rifle. In these cases the lug has been custom fitted to a specific rifle. It's not a flimsy little shim. Shims DO NOT belong on a barrel/action fit up.

Since it's a Howa 1500 with the lug part of the reciever itself (Win M70 style). Fitting a lug won't work to correct the fitment. Howa's don't use a rem style lug. Which makes the shim even more questionable.

I would remove the shim. Thread the barrel on. Use a bushing bump die. Like a Forster die. .005 ain't much. It's just going to be a tight chamber. Might build pressure a little faster. The brass can be bumped back enough to work.

 

[ntsqd]

I don't have a problem with a shim not being the "Correct Method", all too often that method is the only one that the person saying it knows to work. Which is fine, but it ignores he fact that there are always other ways to end up with the same results. Shims are used in a lot of other high risk assemblies without a problem.

Assuming that it doesn't create a situation similar to an excessive headspace condition I don't have a problem with using a shim from a safety perspective.

I do have a couple of concerns. First is the cutting of the shim stock material. Really easy to leave a burr that upsets the actual resulting thickness. The second is that it's another part in the accuracy of the system, and could introduce unknown variable(s).

 

[Darryle]

Another factor we are overlooking is the degree/clock of the barrel in relation to that chamber being .005" short

All to often I have found that when using a shim to clock a muzzle device or an AR barrel nut, my math says one thing, but the shim said something else.

Corrected anything in this type of scenario, so, it may in fact be a .005" shim that corrects it.

 

[JD284win]

Another factor we are overlooking is the degree/clock of the barrel in relation to that chamber being .005" short

All to often I have found that when using a shim to clock a muzzle device or an AR barrel nut, my math says one thing, but the shim said something else.

Corrected anything in this type of scenario, so, it may in fact be a .005" shim that corrects it.

"Clocking" the barrel is irrelivant. It does nothing. Unless you want to see any type of factory lettering or when lining up flutes or and extractor recess for a mauser or Win M70 type action. Muzzle breaks are easy to adjust on the lathe for alignment.

 

[Darryle]

"Clocking" the barrel is irrelivant. It does nothing. Unless you want to see any type of factory lettering or when lining up flutes or and extractor recess for a mauser or Win M70 type action. Muzzle breaks are easy to adjust on the lathe for alignment.

My point being, because it needs .005" in the chamber doesn't necessarily mean a .005" shim will be correct because of crush.

My verbiage is probably incorrect, sorry for that.

 

[JD284win]

My point being, because it needs .005" in the chamber doesn't necessarily mean a .005" shim will be correct because of crush.

My verbiage is probably incorrect, sorry for that.

Either way. Shims don't belong between a barrel and action. If I hand a client a barrel with a shim. I'll never see a rifle job ever again. Granted seems to be a personal gun. Still gotta have standards.

 

[dennisinaz]

If you can find the right shim, the method you propose will work fine. It's not the best way but certainly will work. You need to make sure the shim doesn't bind up and throw all your measurements off .
Your shim needs to be the right size to insure that it doesn't collapse over time.

 

[aschler]

A recoil lug is a component of a rifle. In these cases the lug has been custom fitted to a specific rifle. It's not a flimsy little shim. Shims DO NOT belong on a barrel/action fit up.

Since it's a Howa 1500 with the lug part of the reciever itself (Win M70 style). Fitting a lug won't work to correct the fitment. Howa's don't use a rem style lug. Which makes the shim even more questionable.

I would remove the shim. Thread the barrel on. Use a bushing bump die. Like a Forster die. .005 ain't much. It's just going to be a tight chamber. Might build pressure a little faster. The brass can be bumped back enough to work.

The shim is not flimsy in the orientation it would be installed in.

 

[aschler]

So, what's stopping the shim from crushing?? Is it still .005" after the barrel is tightened onto it??
We need answers, not opinions…

Cheers.

You would want a 0.006" thick shim or a 0.007" thick shim if you want to error on the side of caution.

 

[aschler]

Who makes a shim that is 26mm id that is .005" thick and has an outside od of 30mm?

I would agree, but I looked for a single round shim and could not find one, maybe your Googlefu is better than mine

You can get them from Grainger, I'm sure other industrial supply stores will have them as well.

The OD will be 1.5", the OP already identied this problem and is okay with trimming after installation.