headspace gauge for AR15?

[freestylmx]

Ive been reloading for a while and never have used a headspace gauge for the AR15 because I always figured the full length resizing die puts it back to spec (or close enough for the AR)

Now Im getting into using headspace gauges for my bolt rifles (don't know why I never did this from the start) and am wondering if anyone uses, or sees the need for one with autoloaders.

Im wondering if I should get one and see if any accuracy is improved by bumping the shoulder just enough to get reliable feeding but not all the way back as the fl die does

 

[greenheadcaller]

Yep I do.

Main reason I manage/control/set my headspace is because many FLS dies set shoulders/headspace all the way back to SAAMI minimums ..... so the brass they resize will work for the masses and chamber in the masses guns (even in the instances where chambers are cut closer to minimums than maximums).

In most instances, and almost always in "stock/not custom chambered" AR's, this is setting them back quite a bit further than they need to be. However....if your reloads are going to be shot in multiple unknown AR's ...or full auto...don't mess with it.

However, if reloading for same gun.....Rule of thumb....in an semi-auto loader is (at least in .223 or 5.56) ... you want to set the shoulders back .004 (stick to the rule, but many only go .003 and some only .002 if shooting same brass in same relatively well kept and routine cleaned gun and not if full auto...but again...the "rule is .004" so to protect the innocent - me - I am not advocating less 8)

In my experience including .223 chambered AR's and 5.56 chambered AR's ..... a "Stock" LEE FLS die for example .....will set the shoulders back from .004 to .01 more than they need to be according to the rule.....for what that's worth....each one is different. Other die manufacturers force the user to adjust headspace in order to set the die up correctly...so these users are already doing it (tailoring headspace) or may be doing it.

At best.....overworked (but still in spec) brass will fire off and go unnoticed....no big deal unless you plan to reload it a number of time. "Overworked" brass will stretch more and not last as long...this being the biggest consequence. (Think .01 overworked and shot 5 times = .05 stretched.....that's why a lot of guys can't get more than 3-4 firings out of their AR brass before they split above the base) Cut the overworked measurement in half...and they last twice as long...etc. etc

In other instances....everything will seem fine but you will notice primers will pancake/stove pipe a little and/or seem to show pressure signs a little sooner (because brass/the unfired round is driven forward a little in chamber when firing pin hits primer because it has room to go ...then primer goes off shooting primer back to the bolt face filling the void...quickly followed by brass stretching back to the bolt face after neck/shoulder seals...and pressing primer flat until it fills the primer hole......it isn't much, but you can see it when you deprime...there will be a little lip on the top of the primer). Visualize primers that look like tiny Uncle Abe's hats even though they aren't over pressure.

Is accuracy affected? Good question.... I always resize/reload to specific headspace in my AR's so I can't really tell ya. ... but it's my opinion that fire formed brass resized to a headspace for a particular chamber is more accurate. A lot of accuracy depends on so much more than headspace though for sure imo. That said...most store bought ammo is headspaced to minimums to for the same reasons the die folks do it and for the same reason the AR Chambers are typically cut to saami maximums (to cover their butts and make sure their stuff works in everything and in the case of the chambers...shoots everything even when dirty).

Main thing short headspace brass hurts (as long as its still in spec) is brass life.

Going the other way though......a lot more can go wrong in a semi auto or full auto if headspace of sized brass is too long......particularly if the bolt somehow locks or partially locks on it .... ......so no reason to push it too far the other way either.

Short answer (about time, huh..lol) ....yes, I adjust my headspace when sizing brass even in my ar's .....so my brass lasts longer and I dont' get bad reads on my primers.

hope this helps

 

[greenheadcaller]

I should have also added this.

Just remember....if you are trimming brass to a consistent length....for every .001 you add to the headspaced length on your sized brass.....the same .001 will get trimmed from the neck.

So on AR brass....because I know I am sizing them over SAAMI headspace minimums in almost every instance in my chambers ......I never trim brass below 1.75

Probably could and still be ok ... just sayin.

I get windy...sorry bout that...hope this helps

 

[freestylmx]

thanks for the reply. Headspace gauge to get longer brass life makes sense and is a good enough reason for me. I have noticed that after full length sizing I do have to trim quite a bit in most cases from them stretching. Ill get one and bump back to .004 and maybe try some at .002-.003 and see if I still get reliable feeds