Do I need to full length re-size in a semi if


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stoney1666
March 24, 2008, 12:40 PM
I had already done that before shooting it, I also trimmed them.

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rcmodel
March 24, 2008, 12:43 PM
Yes. Probably.

Most semi-autos don't have a lot of camming power, either opening, or closing, compared to a bolt-action.

If you don't full-length size you may run into functioning problems.

rcmodel

par0thead151
March 24, 2008, 12:53 PM
full length resize & trim every time, otherwise you will run into problems. and honestly, what fun is it to be ducking around with a jammed up rifle at the range?
not only do you not get to shoot, but if others know its reloads they will give yous hit about it... at least my shooting buddies do, then again i always rub in how much cheaper i shoot for than they do. i shouldent complain though as i get all their once fired brass:neener:

Jim Watson
March 24, 2008, 12:54 PM
Yes, definitely, no doubt about it. You will have nothing but trouble if you do not full length size the brass for an automatic, every time around.
I recently saw a guy who was advised to neck size by somebody who either did not know it was for an auto or did not know as much as he thought he did. The shooter did not get off half a dozen shots and had to scratch from the match. Then buy a full length die.

snuffy
March 24, 2008, 01:11 PM
Maybe. I did a little test last weekend, I loaded some .223 that had been fired in MY BUSHMASTER AR. I used the lee collet NECK sizer, 4 die set from lee. The shells loaded, chambered, fired, and ejected without any problems. One thing I did NOT do is try to unload one that had been chambered but not fired.

This was winchester brass, not trimmed since the last loading, 24.5 gr. of benchmark, 60 gr. V-max bullet. Not looking for a group, not willing to wade through snow to get to the 200 yard target, just function testing, aiming at a clear spot on an old target. First time loading benchmark. Also first time using the lee FCD in .223.

Once we are finally rid of the snow, I'll do some accuracy tests with this die set-up in my new lee classic turret.

So my answer is maybe. Conventional wisdom says ALWAYS full length resize for ANY semi auto. Most times that's the right answer.

rcmodel
March 24, 2008, 01:59 PM
Thats why I said Yes, Probably!

rcmodel

paperpuncher49
March 24, 2008, 06:24 PM
Snuffy said:
Maybe. I did a little test last weekend, I loaded some .223 that had been fired in MY BUSHMASTER AR. I used the lee collet NECK sizer, 4 die set from lee. The shells loaded, chambered, fired, and ejected without any problems. One thing I did NOT do is try to unload one that had been chambered but not fired.

I would agree with maybe. Conventional reloading wisdom, which sometimes is really urban legend, says to FL size each time. About two years ago I tried the same experiment in an Eagle Arms AR. Lake City brass, Lee collet neck sizer, and RCBS seater, no crimp. Reloaded 10 rounds. Functioned flawlessly. Repeated 4 more times with same 10 pieces of brass with same result (total of 50 rounds). I did extract rounds after having been chambered with no problems. That being said, it was an experiment that worked. I typically still use an RCBS X-Sizer whenever I load for the AR.

CU74
March 24, 2008, 11:36 PM
Get a headspace gage for the calibers you are reloading. (I have the LE Wilson gages.) The headspace gage not only lets you know if the shoulder-to-base measurement is correct - that's what you're resizing for - but also lets you check the overall length. I've found that I can use .30-06 Lake City brass twice before trimming the cases. For twenty bucks or so, headspace gages are well worth the expense.

Bullet
March 24, 2008, 11:38 PM
I only partial resize using a Full-Length sizing die.

As an example when I resize my cases for my AR, I measure a fired case and then adjust my sizing die to resize the case .002 to .003 smaller between the base of the case and the datum point on the case shoulder (and by the way this measurement is different for each of my AR’s). This amount of resizing is enough for reliable chambering with out sizing my brass more than necessary.

When you resize your case you are reducing the distance between the base of the case and the datum point on the case shoulder. A RCBS Mic measures this distance on a fired case and can be used to tell how much you’ve reduced this measurement by resizing. There by allowing you to not size your case more than desired. A Mic is used to accurately set the amount your sizing your cases.

http://www.midwayusa.com/esearch.exe/search?search_keywords=RCBS+Precision+Mic&category_selector=all_products&Click+to+Begin+Search.x=7&Click+to+Begin+Search.y=11


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entropy
March 25, 2008, 11:23 AM
No, you should be Small Base resizing them for a semi-auto if reliability is important to you. If not, you might as well neck size them and manually function the weapon. I'll amend that to for a NATO spec chamber, full length sizing should suffice.

Grizzly Adams
March 25, 2008, 02:31 PM
Yes! Most manufacturers recommend you use Small Base full length resizing dies for semi-autos to operated reliably. I have had people bring guns in with stuck cases and with extractors broken due to only neck sizing! That's if you can get the round into full battery!

FM12
March 25, 2008, 06:52 PM
If shot in the same weapon, better functioning than if swapping brass around in different rifles. I wouldnt use these loads for defense or match work, just for plinking.

steve4102
March 25, 2008, 09:05 PM
OK, FL sizing is a must for an auto-loader. But why? Why is an auto loader any different than a bolt action when it comes to sizing brass? Well, I'm goin to tell ya.

When a round is fired in a bolt action the brass expands to the exact dimensions of the chamber and then springs back just a bit. This spring back allows for easy extraction. Neck sizing this brass will usually allow for easy chambering until the brass can't spring back enough. Then the brass needs the FL or PFL treatment.

Things are a lot different in an auto-loader. When a round is fired in an auto-loader the brass is usually still under a bit of pressure while it is being extracted. This tiny bit of pressure will cause the brass to grow above and beyond the "exact" chamber dimensions. This increase in case size is dependent on among other things the speed of the powder used and how it's burn rate relates to the port pressure of your particular rifle.

An example would be my Ruger Mini-30 with a custom barrel. This rifle has an adjustable gas port so I can open or close the gas system. With the gas port completely closed my fired brass measures 1.185 with my Stoney Point Head/Shoulder Gauge. With the gas port wide open the brass can measure anywhere from 1.185 to 1.24 depending on the powder and charge. This measurement can also vary as much as .004 with the same exact load.

The best way to keep your auto-loaders running smooth is to get a Stoney Point Gauge and set your dies up so you have adequate shoulder bump and minimal head space.

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