resizing for ar 15

[cjmac]

So havent loaded much for auto rifles ... is 3 thousands shoulder bump enough for an AR 15 ?

 

[22DASHER]

So havent loaded much for auto rifles ... is 3 thousands shoulder bump enough for an AR 15 ?

Reload 20 and shoot them. For my AR's it wasn't, I needed .005 for it to be reliable

 

[jonbearman]

If your brass is once fired, get yourself a small base full length die to put it close to sammi spec so it can form to your chamber.

 

[loneranger04]

Small base die and full length size.

 

[DukeDuke]

I've had good luck with the rcbs x-die

 

[mac86951]

I typically bump the shoulder 3-5 thou. I find reliable feeding depends on chamber, brass manf., and load so feel free to adjust to your rifle

-Mac

 

[akajun]

I set my short line ammo back .005, I use a standard RCBS sizer or a Dillon Sizer/trimmer die, depending on which machine I'm running . I also trim every loading, and lightly crimp with a lee factory crimp die. To date I have not had to shoot an alibi due to failure to feed in over 10'000 rds nor have any of the Juniors whom I load ammo for as well. Brass is still going strong, you'll split the neck or wear out the primer pocket before you get a case head seperation on lake city .223 brass.
My 600yd single load ammo, I only size to . 003.

 

[searcher]

The delimna is safety. I feel bumping .003" to .004" is just right. Any shorter, the potential for problems goes up quite dramatically - any longer and accuracy slides quite quickly and dramatically. I use Redding Full-length "S" bushing dies in multiple A/R varmint rifles.

 

[fguffey]

I would suggest you learn to measure the length of the chamber from the shoulder/datum to the bolt face first. Finding yourself in a large crowd of reloaders that can not do that measure the length of cases from the shoulder to the case head before firing, then fire and measure the length of the case again after firing from the shoulder /datum to the case head.

The difference in length will indicate the effect the chamber had on the case when fired. And you have a choice: Do you return the case back to minimum length/full length size, or do you bump the shoulder .002"? ?

When finished shooting and measuring you should know the length of the chamber from the shoulder to the bolt face in thousandths.

F. Guffey

 

[fguffey]

and before you purchase dies you will spend the rest of your life talking about and never using learn how to measure the case. A small base die does not make the base of the case smaller in diameter. The deck height of the shell holder prevents the bottom .125" from being sized.

F. Guffey

 

[bigedp51]

So havent loaded much for auto rifles ... is 3 thousands shoulder bump enough for an AR 15 ?

cjmac

Below is a fired case from my AR15 carbine, I'm loading for three different make AR15 rifles, two are mine and one belongs to my son. Meaning I'm "averaging" the shoulder bump but it varies less than .001 between all three rifles.

Below is the same case after full length resizing and .003 shoulder bump or setback.

Below is a unfired Federal M193 cartridge in the Hornady gauge, meaning my full length resized cases are .002 longer in headspace than factory rounds. And the factory loaded ammunition is over .005 shorter than my chamber, and I'm sizing to make my cases last longer.

Below are some of my .223/5.56 dies, the RCBS black box is a small base die and makes the base of the case .0005 smaller in diameter than the standard green box RCBS die. The big difference between these two dies is the small base dies will size the case further down the case.

Ignore the comment about the shell holder preventing small base dies sizing further down the base of the case by fguffey, small base dies "DO" size further down the case. And if the case needs to be sized around the shell holder area then your loading way over max and need your head examined.

Bottom line, the AR15s military chamber is .002 larger in diameter and has longer headspace settings than a standard SAAMI .223 chamber. I only use my small base die when I purchase once fired or range pickup brass to bring these cases back to minimum SAAMI dimensions. Thereafter I use my standard RCBS full length die and with .003 shoulder bump I have had no problems with this ammunition used in three different AR15 rifles.

NOTE: We live in a plus and minus manufacturing world and your dies and chamber may vary, The small base .223 Redding body die above will make my cases .001 smaller in diameter than my standard RCBS .223 die so nothing is written in stone. Also the brand of case you are using and the hardness in the base web area will affect your sizing methods. Lake City cases are the hardest and .223 Remington and Federal are the softest, and any commercial contract 5.56 cartridges made for the military will comply with military hardness requirements.

 

[Corey Schwanz]

I use a small base sizing die and bump them about .004-005 the last time I checked it. Reliability in my AR is 100%

 

[fguffey]

Ignore the comment about the shell holder preventing small base dies sizing further down the base of the case by fguffey, small base dies "DO" size further down the case.

The only way to size the case head below .125" is use a shell holder with a shorter deck height. or raise the case head off the deck of the shell holder. When sizing cases for short chambers I can reduce the length of the case from the shoulder of the case to the case head .012".

then there are those that grind the top of a shell holder and or bottom of the die.

F. Guffey

 

[bigedp51]

I would suggest you learn to measure the length of the chamber from the shoulder/datum to the bolt face first. Finding yourself in a large crowd of reloaders that can not do that measure the length of cases from the shoulder to the case head before firing, then fire and measure the length of the case again after firing from the shoulder /datum to the case head.

The difference in length will indicate the effect the chamber had on the case when fired. And you have a choice: Do you return the case back to minimum length/full length size, or do you bump the shoulder .002"? ?

When finished shooting and measuring you should know the length of the chamber from the shoulder to the bolt face in thousandths.

F. Guffey

I'm going to tell all the forum members and anyone else reading this posting a very simple way to find your total chamber length. Its not the mystery that fguffey can never tell us in any of his postings. :

1. Take a new unfired case and measure it with a Hornady cartridge case headspace gauge and write it down.

2. Now take a fired spent primer and start it into the primer pocket of the case you just measured for headspace length.

3. Now chamber this case and slowly close the bolt allowing the bolt face to seat the primer as the bolt is fully closed.

4. Now remove the test case and remeasure with the Hornady case gauge, this length will be your chambers total length. If you subtract the first case measurement from the second case measurement this is your head clearance or "air space" between the bolt face and the rear of the case.

NEWS FLASH: No more mystery fguffey datum points, magic feeler gauges or any other BS that never answers the OP questions.

You can now skip over all of fguffeys postings and no longer be bombarded on how fguffey invented headspace and datum points.

The following posting was brought to you by bigedp51 who didn't invent the word headspace.
And now all of you know how to make the cheap bastards headspace gauge. ;D

 

[cjmac]

Wow lots of good info. I have a hornady gauge. The way my die is set up it happen to bump bump the shoulder back 3 thou. I just hate moving the darn thing every time i have to size for my dolt gun. I neck size for it but still.have to FL size after a few times... the brass life for my ar is not a real big deal as i get a LOT of LC brass from people i know that dont reload.

 

['Freak]

“Proper adjustment of the full-length die will keep all dimensions within the tolerances and clearances needed for proper operation of the rifle - including maximum accuracy. Accuracy comes from consistency, and only a full-length sized case is consistently like its mates. Neck sized cases will over the course of two or three firings; not only becoming quite tight in the chamber, but will do so to varying degrees, leading to inconsistent bolt operation and inconsistent barrel harmonics. A fired case hits the inside of the chamber hard enough to initiate an element of the barrel's vibration pattern; do that inconsistently and your accuracy will suffer.”

Germán A. Salazar
http://riflemansjournal.blogspot.com/2010/06/basics-resizing-case-dimension-changes.html

 

[243winxb]

FL sizing on a Progressive press.

If loading on a progressive press, i would want more than 3 thousands. Each station of a progressive may produce a different shoulder bump.

 

[searcher]

When using the same sizing die to load for more than one rifle, the die shims are a great solution. Set the die up to the shortest headpaced gun. If a headspace for another gun is .003" longer, add a .003" shim under the die, etc. Just note on your reloading nhote which shim to use when sizing ammo for that rifle. Get them at Sinclair Internatinal.

 

[CatShooter]

Re: FL sizing on a Progressive press.

If loading on a progressive press, i would want more than 3 thousands. Each station of a progressive may produce a different shoulder bump.

?? ???

But only ONE STATION does any bumping.

 

[fguffey]

Quote from: 243winxb on Yesterday at 07:46 AM

If loading on a progressive press, i would want more than 3 thousands. Each station of a progressive may produce a different shoulder bump.

And then Catfish posted:

But only ONE STATION does any bumping.

Someone has to explaine to catfish the shell plate does not have a designated sizing position, a disciplined reloader would measure the deck height of each position on the shell plate to determine the effect of each position.

Then there is the basic understanding of shop skills. The shell plate hangs out and off of the ram. the cantilever effect reduces the effectiveness of the ability of the press to size.

F. Guffey