If someone could explain this to me Barney style, I’d be thankful. I think I’m doing it right, but I have few questions.
Are you guys bumping the shoulder’s back .003 from where it ends up after being fired? Or back to where it was before being fired? My hornady comparator shows my brass being bumped back to match factory new ammo, with none of it being bumped back more that .006 on the extreme end, if I remember correctly.
You should bump the shoulder of the fired case no less than .003" for a semi-auto rifle.
When a round is fired, it becomes what we call fireformed, which means it has expanded to the size of that specific chamber. Theoretically, you should bump the shoulder no less than .003" from that dimension for a semi-auto rifle. But not all brass expands the same; even like headstamp brass expand differently. I’ve measured as much as .004" difference from the same rifle, same brass, same day, etc. Some brass may expand .003", some .001", some not enough to measure. The easiest way to do it is take the brass casing that has expanded the most, and set your die to bump that one .003". The rest of the brass should be in-spec after sizing with that die setting.
Through trial and error, I know what size my brass needs to be to fit perfectly in each of my chambers. But you don’t want the shoulder touching the chamber, you want it ~.003" away for a semi-auto. This is where the .003" shoulder bump comes in from the fired case.
This whole thing is what we call headspace, which is the distance measured from the part of the chamber that stops forward motion of the cartridge (the shoulder) to the face of the bolt. This is also the same dimension you measure with the Hornady gauge, but on the brass casing. Like I said above, whatever this measurement may be, you want the shoulder of the brass ~.003" away.
I’m not sure if this is what you are referring to with the Hornady camparator, but this is what I use to measure:
If you look at the SAAMI drawings, which can be found through Google, it will show you what size bushing you need to use to measure the headspace of the brass and it gives you a window of in-spec measurements. For .223Rem, you would use the .330 bushing to check if the brass is sized between 1.466" and 1.459".
I hope this helps.
Thank you! That is indeed the tool I was referring to.
I appreciate the recent “shoulder bumping” threads. I JUST bought a Sheridan gauge… no experience yet, figured the only way for me to learn is to start mashing test cases and measuring, just to find the “limits”.
Can someone explain how the Sheridan (or Wilson) gauge is the same or different as that Hornady tool? Sounds like maybe the Sheridan is just a check, while the Hornady allows one to measure. Yeah?
Exactly, Sheridan gauges just check to see if the casing is withing a certain in-spec range. The Hornady Headspace gauges give you an actual measured number.
In an ar15 where extraction is happening while there is residual pressure case guages are the best tool for the job. Especially when feeding multiple rifles. Thats why with the hornady guage you get inconsistent numbers. With the guage you size everything to fit the case guage and your good to go.
The hornady tool is a great tool, but it is not the best for checking headspace on brass fired from an ar15.
I disagree, the Hornady gauge is the ONLY way to go if you want ammo custom tailored to YOUR specific rifle. Sheridan gauges don’t measure anything for you. They only check the sized brass to make sure it’s within the SAAMI spec window. Hell, most fired casings won’t even fit in a sheridan gauge anyways due to the neck expansion. I for one, want all of my ammo to be EXACTLY the same, custom sized for my rifle(s). From headspace, powder charge, OAL, etc. ESPECIALLY match grade ammo. The more consistent and the more custom tailored your loads are to your rifle, the more consistent your results will be.
IMO, sheridan gauges are ok at best. They are fine for regular plinking/training/whatever ammo, but when you are trying to produce the most consistent ammo possible, they are the last thing I would choose. If you want ammo that is custom sized to your specific rifle, a headspace gauge is the ONLY way to go.
Just to clarify, I know why I get inconsistent fireformed measurements with the Hornady gauge. There’s no getting around it due to the residual pressure as you mentioned, it’s just part of the semi-auto life.
FWIW, I have a sheridan gauge for each caliber I own, but I haven’t touched them since I got the Hornady gauge.
A case guage does not limit accuracy at all. Fire forming loads usings false shoulder can shoot sub half moa, and that brass is doing a hell of a lot more growing then the couple thousandths case guage sized brass is doing. Accuracy is about consistency.
Sizing by the measurement of the longest case is by no means tailoring the brass to your chamber. I have measured cases fired from the same ar that varied more than .003. So by bumping the longest one by .003 others might not be bumped back at all. That is not leading to consistent results. If your load is shooting sub moa with the brass sized the way you are, it will be sub moa sizing to a case guage.
In your post you said most cases will not fit in a case guage after firing. They are not supposed to. If you can not load match grade ammo using a case guage it is not the brass holding you back it is something wrong with your technique.
Exactly how much does brass usually grow when being fired from a 5.56 chamber. If I remember correctly, I bump the casings all back to match factory new ammo. Now I’m wondering if that wasn’t too much, and if that isn’t going to shorten the case life. Until I get a couple thousand reloads down range, I plan on reloading each case only twice.
Sizing the case more is going to shorten its life if you do not anneal it. You should still be able to get more than 2 loads safely. Using a case guage is helpful when feading multiple rifles. I have only used dillon case guages so incan not comment on the sherridan.
How much a case grows after being fired is going to be different. It is going to be rifle dependent. I will measure some and report back.
I just measured 3 once fired pieces and got 1.460, 1.463, and 1.465. The 3 pieces of factory loaded measured 1.458, 1.4575, and 1.457.
If you set your sizing die to bump the longest piece by .003, you have cases that are not even being bumped. That is just the first pieces I grabbed. I know from measuring in the past they can vary more than that. From my numbers if you bump back to factory length that less than .010. Dial that up on your calipers and see how much it really is.
Will it shorten case life? Yes. How hard is it to find 223/556 brass? It is one of the most abundant calibers out there. I know for me I will stick with the consistency the case guage provides.
Case gauge is the only way to go for feeding a semi-auto, aside from that I’m having no problems making 1 MOA or better ammo after using a case gauge to set my full length resizing die. Plus I’m feeding two AR’s and there’s no way in hell I’m going to try to custom size brass for each one and keep two resizing dies in two tool heads, and separate all my brass. That is just freaking stupid.
Instead I’ll enjoy shooting ammo I know is dimensionally correct for any in spec .223/5.56 chamber, and that shoots well in a good barrel. Chasing minute improvements in accuracy is not something that interests me all that much anyway, once I get a load that works 100% and gives me good accuracy I start making a bunch of it to shoot. The way I see it, I’m more likely to benefit from regular practice with ammo that is capable of .75-1.00 MOA (or even larger groups) than I am from shooting small quantities of test loads trying to shave .25-.50 MOA off of what is already a good load. It’s much easier to crank out ammo from a set up press, powder measure etc than it is to change shit around every 5-10 rounds for an inconsequential improvement in accuracy.
I agree with everything you posted coal dragger. I have been reloading a lot longer than I have been loading for AR type rifles. When I started loading for the AR I realized trying for a minimum bump is pointless. You get so much variance in the fired case that a minimum bump leaves you with brass that is inconsistent and can cause problems. Using a case guage simplifies everything.
Those measurements are all from the same rifle. I have not shot anything but my mrp this year. So if a case can vary by that much in one chamber your just chasing your tale as far as sizing goes until you use a case guage. Unless you can shut off the gas system and have a straight pull bolt action all the measurements are meaningless.
Measure, schmeaure.
Any semi auto fired ammo should fit into a case guage. If I’m setting up a die for minimum bump for a bolt gun, I simply turn the die down until the bolt just closes nicely. I have none of these measurement devices.
If I understand you correctly, about the best you can do for AR reloading is to adjust your dies to f-l resize until the case head is level with the upper step of the gauge (rather than the lower step or in-between).
Pretty much. My fl resize die is set in between the high step and low step on a Dillon case gauge. The difference between the high and low step is tiny as it is.
I adjust it to fall in between the steps on my dillon guage. A lot of factory ammo I have checked with my dillon case guage were even with the bottom step. Some factory falls in between the steps.
What I was getting at is that using head space guages like hornady are worthless for AR loading.
I agree. Flirting with the upper limit can leave you with ammo that won’t chamber well… and won’t extract if you need to eject a live round. I learned this the hard way.
I only bump my shoulder back .002 each reloading but there is some other rules I set for myself. I’m a little anneal about sorting my brass and keep it sorted for each rifle and the times it has been reloaded. Fourth reloading is its last and it is either left laying on the ground or collected seperately for the scrap bin.
The reason for this is as the brass work hardens the bump will get inconsistent due to two reasons, work hardening or inconsistent lubing. I don’t anneal AR brass (yet - been able to control the impulse) but each cycle through the press I check/measure. When the bump starts getting inconsistent due to work hardening I have no other choice but to add to the amount I’m bumping or anneal the brass to reduce the spring back. This process has worked well for me.
For brass from and unknown source, i.e. Widners or other surplus supplier it is FL sized to SAMMI or a case gauge and trimmed after firing in a perticular rifle it is kept with the rifle for its useful life.
I understand the work hardening. I even posted it will shorten case life, but unless im running hot loads I can get 5 loadings no problem.
If your only bumping your cases back by .002 how do you choose which case you use for the measurement. I measure cases fired from the same rifle and the measurements varied by mor than .004. So unless your cases are coming out consistently I do not see how you pick which case to size.
Measure more than 10 cases. I generally measure/record 40-60 cases each reloading until I feel comfortable with calling X my max length to work with. I generally get about a .004 spread in OAL with a few highs + .001-.002 and some lows that range from nothing to the top of the bell. An example would be Factory to + .001 (12), + .002 (8), + .003 (15), + .004 (21), + .005 (3), + .006 (1) and + .007 (0)
To get a max chamber size on a new rifle or bolt and barrel combination I load a virgin bag of Winchester factory brass with a previously established load. I also run a box of m193 and m855 as a factory known pressures and compare. If the chamber is pretty tight SAMMI to +.002 I usually get pretty consistent readings but at +.004 and larger it tends to take a couple of firings to find the true max and even then that is measuring the brass after spring back. I measure all the factory cases and about 20 -30 of the winchester cases. If it is all over the place perticularly with new brass that is fl sized to SAMMI -.004 to .006 coming out of the bag, I’ll take the the longest length before it drastically drops off in averages, bump the winchester back .002 from that OAL and reload it. On the second firing I usually find a consistant max chamber length.
This isn’t always the case though, my SCAR 17 (7.62 x 51) is in the SAAMI .007-8 range based on a 308 SAAMI chamber gauge. I’ve ran the same batch of hard military brass through it and I think I’ve finally found the bottom. The virgin brass is SAAMI - .004 to .006 so it has to grow .011 to .13 so I’ve been bumping it to SAAMI + .005 but it is starting to work harden and I’m starting to get inconsistant measurements so either I anneal it or add more to the bump. The rifle has not had a chambering or extraction problem since new with about 1k through it. Granted its not a benchmark test as I’m only pushing a 145 gr bullet at a midrange loading with ball powders (banging ammo).