setting headspace from factory ammo?

[logic factory]

i understand that most will stress the importance of, at the very least, buying a go gauge for ~20 dollars to dial in head space. i get it but i still do not get where the issue lies with setting headspace off factory ammo. i have read that most factory ammo is a little undersized to promote the best chance of proper feeding in most rifles. i can not recall every reading anyone mention exactly how much it is undersized. as nice as it would be to have this information im not sure it would matter in the following scenario.

if one is only going to be shooting the same factory ammo all the time why couldnt they just headspace off that cartridge? i understand that the once fired brass will likely not be sized correctly. does this even matter if one will only be shooting the same factory ammo and load? would it be a better idea to set headspace with factory ammo and one piece of tape(.001"-.002") on the head to simulate closer to saami(?) standards?

it is difficult for me to understand outside the likelihood of incorrectly sized fired brass where there may be other issues using this method to set head space on a rifle that one can adjust headspace easily on; i.e. barrel nut. if one chances facotry ammo they can check headspace and, if need be,tailor it to new ammo they will shoot.

i have read of most diy headspacing threads using once fired brass in a proper saami regulated chamber to set their headspace. i almost think, it would be safer to set headspace off the factory ammo you will be shooting than not knowing how well headspace was set to saami standards on a once fired brass; even if it is at the expense on not being able to reload the collected brass for factory ammo headpsaced rifle.

lastly, i would almost feel safer knowing the headspace is set for the exact manufacturer and load i will shoot than using a possible larger sized saami specified go gauge. is this rational or am i missing some important variables?

any feedback is welcome on this topic.

 

[Ballistic Artist]

Re: setting headspace from factory ammo?

LOL. Just buy a set of H.S. guages. Fire your shells then only size the neck. It works very well and there is no wondering. But I see your point. I mean thats how you set H S on an Ackley chamber. Should close on a live round, should NOT close on a go guage.

 

[logic factory]

Re: setting headspace from factory ammo?

thank you for your feedback. i did not know that about the improved cartridges. it seemed like the couple images i have seen that the necks are also pushed forward in addition to the increased angle 30-40? hard for me to visualize how even a regular hs gauge would be of any use in the chambers of a.i. rounds i have seen. this is only based off the internet as i have never seen an improved round in real life so my understanding can be incorrect here.

if i can keep the thought of reloading out of my mind the decision becomes easier to make. i can get why some would not "gamble" with 20 dollars and the peace of mind it may create. but i am trying to understand if "gamble" is being used liberally here.

 

[turbo54]

Re: setting headspace from factory ammo?

From what I've seen, factory ammo runs from .001" under "go" to as much as .010" under.

If you HS according to, say, even as many as 10 factory cartridges, there is a strong likelihood you're going to find SAAMI compliant ammo that doesn't fit your chamber.

Is this unsafe? No, particularly if you are a fairly experienced hand loader.

Trouble I see in this is having a chamber you honestly don't really know the size of.

Rather than a 308 chamber, you'll have what I have dubbed a 308BI chamber. BI = Bohem Improvised

 

[logic factory]

Re: setting headspace from factory ammo?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">.</div></div>
thank you for providing some undersized numbers for me.

in your experience have you seen a .009" variation in the same factory ammo load; i.e. hornady match 178 bthp?

i would assume as long as you only shoot the same specific bullet from a manufacturer that they keep their rounds within a couple .001's.

having an unknown chamber is an okay compromise for me at this time because i do not plan to be reloading anytime soon.

i had google help me investigate the allusion to bi as i was unfamiliar. it appears i found the source of the bi comment and can appreciate the humor in it now. i will never, sell this rifle but there is a good chance i will have the hs set properly one day when i plan to reload. until then it will remain a 300 blackout lfi or remington 220 subsonic chamber.