Neck sizing for semi-auto? Yes, no or maybe?

[David_S]

I am sure this topic has been done to death many times before but just want to check. Up to now I have been reloading for bolt action rifles and generally have neck-sized only. I now have a Lithgow L1A1 SLR (.308) with match barrel and want to know whether I should full-length or neck size the cases. (I will have to get new dies.)

Conventional wisdom seems to be to full-length as neck sizing can cause jamming. Also the semi's extraction mechanism is harder on cases so you don't get the benefits of increased case life that you do with bolt-actions. Is this correct? Also the marginal increase in accuracy with neck-sizing would appear to be pretty irrelevant with an SLR?

And btw has anyone got recommendations for bullets and loads for this rifle. In my other rifles I use and like Hornady projectiles either SST or SP. But what weight does the SLR like? I use ADI AR2209 powder (= Hodgdon H4350) for my other calibres and would prefer to use it for the SLR to simplify matters.

Thanks

David

[chris in va]

I'm brand-new to reloading for my Garand, but I was told by numerous knowledgeable people that full length sizing for semiautos is needed, not neck sizing. I also went with the FCD to prevent bullet setback which was a problem.

But don't take my word for it, let the other guys chime in first.

[croc4]

its best to full length sizing, the semi's don't have the camming strength to close on a round that might be a little off, so you could end up with more failures to feed/fire. And given the life of brass will be shorter from a semi (in general) from the abuse it takes, you won't end up gaining much as you would from a bolt gun.


Croc4

[farmerboy]

small base

[David_S]

I assume it is best to keep away from Federal primers as being too sensitive?

[farmerboy]

Your gun may work with full length dies, you may have to try and see but alot of semis need the small base that brings them down to smaller diminsions for autos. My bet would be small base and dont worry about shooting one or two and then having problems. Abot bullets, My personal favorite is the Hornady SST in 165 grains. Extremly accurate, and devastating on impact. I've probably reloaded around 500 for me and my son.

[oneoldsap]

NO !

[darkgael]

Disclaimer: I don't have a semi-auto .308 rifle.
I do have an AR15. I do have a 5.7X28 pistol.
I have found no problems at all, ever, with NK sizing once fired brass and using that necksized ammo in these guns. I have had 100% functionality.
I have not taken the NK sizing past two iterations; most of the time, since I have a lot of brass, it has been only once.
If I had a .308 and was starting with new brass, I'd give it a try for the second firing. It saves a bit of time.
Pete

[steve4102]

From The Experts at Sierra.

Sizing

Full length sizing is the only option in the Service Rifle world. Minimal sizing does have its place in bolt actions, particularly where top accuracy is the goal. It can also be used in some other types of actions when reliability is not a top priority. However, anything other than full length resizing is a potentially serious problem with the Service Rifle. The case needs to be resized to the point that it will enter the chamber freely, completely and with absolutely no hint of resistance whatsoever. Failure to follow this simple practice is an invitation to some major headaches.

The most common problem is the failure to fully chamber the round. This is troublesome at best. Considering the force with which the bolt slams home, it can also wedge the round tightly enough in the chamber that it is very difficult to extract without damaging the rifle. In the worst case scenario, it sets the stage for an out-of-battery firing when the trigger is pulled. Improper or insufficient resizing, particularly when combined with a high primer, is also a leading cause of slam-fires.


Neck Sizing

Neck sizing is a popular technique among accuracy-minded reloaders and frequently an effective way to improve accuracy. In essence, it amounts to sizing only the neck portion of the case while leaving the remainder of the shoulder and body untouched. This provides that “custom-fit” of the brass to chamber that so many shooters are working toward. Chambering a cartridge that has been neck-sized will normally give some slight resistance to closing the bolt. This is perfectly normal and to be expected when using this technique. While it’s a minor detail with the powerful camming forces of a bolt-action, this can be a serious problem with a service rifle. It can cause a failure to fully seat and chamber, effectively jamming the rifle. If the lugs have partially engaged, this can be a very difficult stoppage to clear. Under extreme circumstances, it can even lead to a slam-fire. The solution to these aggravating and potentially dangerous problems is simple: Don’t neck size for semi-auto rifles. For any reason. Ever.


Link to entire article.
http://www.exteriorballistics.com/re...sgunreload.cfm

[darkgael]

Don’t neck size for semi-auto rifles. For any reason. Ever.

You make a good case. I haven't tried it in a while. After that article, I'll abandon the idea. Mostly, I load from a factory case of new brass; it's when I use that up and start to cycle through the once fired that I think about saving a little bit of time.
Thanks for the link.
Pete

[Mike Irwin]

It MAY work, but chances are it simply won't be reliable.

[Slamfire]

First choice of powders in these Nato semi autos are powders in the IMR 4895 burn rate. This includes IMR 4895, AA2495 and H4895. These are all stick powders and are extremely close to one another in burn rate. AA2495 is Accurate Arms copy of 4895, but stupidly they gave it a confusing name. IMR 4895 was the powder used in the NM ammunition.

A ball powder that was popular with the Highpower M1a shooters in the late 80’s is AA2520. Accurate arms told me it follows the 4895 pressure curve.

I would use nothing faster than IMR 3031 and nothing slower than IMR 4064. Both of these stick powders shoot outstandingly in the 308, but the sticks are long and don’t throw as well as IMR 4895.

For gas guns, faster is better than slower. Stay away from 4350.

Use a case gage when full length resizing and size to gage minimum. The low step in the second picture. As stated before, never ever do anything but full length resize for a semiautomatic.



I recommend small base dies for gas guns, but you need to use an adequate case lube or you will stick a case in the die. The only two lubricants I recommend are RCBS water soluble or Imperial sizing wax.

You will find that the FAL is hard on brass. It is a rear locking mechanism, the entire bolt is under compression during combustion. Steel stretches about a ten thousands per inch, (guess) so add up the inches and your cases are going to be stretched that much more than a front locking mechanism. Add the fact these rifles are designed to open up when there is residual breech pressure, your poor cases will be lucky to survive five reloads before case head separations.

With a 155 Nosler match, 42.5 grains IMR 4895, LC case, CCI #34 primers gave me right at 2700 fps. That is as fast as you want to go in this rifle.
With a 168 SMK try 41.0 to 41.5 grains IMR 4895, LC case, CCI #34 primers. This load is a common match load for M1a shooters.

Seat to magazine length or less (like 2.750") and don't worry about bullet jump or the amount you are seating off the lands. Bench rest reloading practices have little to no useful application with service rifles, or hand held rifles for that matter.

[David_S]

Thanks everyone for your advice, I am glad I asked. I never imagined there would be so much difference between lreloading for a bolt action and a semi. I think you have saved me a lot of time.

I never knew about small base dies either, Farmerboy, so thanks.

And thanks also to Slamfire for the reloading info. This is just the sort of information I was looking for. By good chance I already have ADI AR2206H (=Hodgdon H4895 which I believe is actually made by ADI) as I was experimenting with it in a .243 with 55gr bullet.

David

[CrustyFN]

I would use a FL sizer. I don't know anybody that used a small base die in a stock AR. We shoot all day long with no problems using a regular die.

[ForneyRider]

I tried it with my Lee neck die and couldn't get it to chamber fully and was a beast to remove.

Precision Shooter Primer had an article that talked AR-15 with Wylde chamber that shot best with neck-sized brass. They shot 69gr SMK in Remington brass with various powders.

I use f/l dies for semi-auto and lever.

[totaldla]

Ya know, as soon as I see a blanket statement without supporting analysis, I automatically assume the statement to be crap (and it usually is).

[farmerboy]

I've also seen statements with supporting analysis and every bit of it is a bunch of craqp also. Sometimes if you dont know atleast you can post a question here, get different answers or point of views. Do your homework and find the truth. Sometimes theres more ways to do something, faster than others or just different and then itll be up too you to decide how you want to do it.

[steve4102]

Ya know, as soon as I see a blanket statement without supporting analysis, I automatically assume the statement to be crap (and it usually is).

And what statement might that be?

[CrustyFN]

And what statement might that be?

I was wondering the same thing.