What is different about loading for an AR?

[brewer12345]

Other than needing a harder primer and making sure the bullets won't move as they cycle through the action, is there anything I need to know about loading for an AR vs. the same cartridge in a bolt gun?

 

[BBarn]

FWIW, I use standard primers and standard dies and treat them the same, but I'm typically not at the top end of permissible pressure. No problems so far as long as the sizing die is adjusted to touch the shell holder at top of ram stroke when sizing a case.

 

[Hugger-4641]

Brass with crimped primers will make you say bad words. Avoid it if you can or get a swager and extra decapping pins.

 

[BreechFace]

-Full length resizing if sharing ammo between AR's or reliability is paramount
-Harder primers due to floating firing pin (Rem 7-1/2, CCI 41's, etc)
-Magazine COAL restrictions STANAG magazines
-Crimped primers needing to be swaged
-Loads need to be able to cycle the action (semi-auto)
-Loads need to work with feed ramps reliably (COAL, brass trimming, etc)

Can't think of anything else that is specific to AR's in 556.

Now if one gets into calibers other than 556 then there are other items one needs to be aware of specific to calibers.

 

[Hugger-4641]

Forgot to mention COAL limit. You will be limited by mag length in the AR. So 77gr bullets are usually the limit.

 

[brewer12345]

I will be starting out with 350 Legend and eventually moving on to 223. Sounds pretty straight forward.

 

[Ferris]

One lesson I learned is powder speed matters in an AR vs a bolt. Most newer manual spec powders that can be used in both, BUT it can make the difference.

The best illustration I can think of is... H380 USED to be a powder for 308, well I had an old manual and tons of H380, loaded it up. It was actually a good load minus cycling was a mess, it was ejecting at 1 oclock ect ect maybe I could get it to work with an adjustable gas block but in the end it was too slow causing too much pressure at the port.

 

[MEHavey]

I will be starting out with 350 Legend and eventually moving on to 223.

Diving off the high board into the deep end right at the start ?



.

 

[brewer12345]

Diving off the high board into the deep end right at the start ?



.

Eh, its what I like to shoot. Already load 350 with a cast bullet for the bolt gun.

 

[Archie]

Loading for a gas operated autoloading rifle traditionally requires 'faster' powders than using the same cartridge in a bolt gun. Stick with loading manual recommendations rather than do much experimenting.

Breech face makes an excellent list.

 

[brewer12345]

Loading for a gas operated autoloading rifle traditionally requires 'faster' powders than using the same cartridge in a bolt gun. Stick with loading manual recommendations rather than do much experimenting.

Breech face makes an excellent list.

I am hoping to work with 2400, as Hornady publishes data for it and I have a bunch. I want to start making FMJ fodder using RMR's 147 grain truncated cone 9MM bullets as they are about the size and shape of the factory FMJ. Hopefully 2400 will be fast enough to do the job.

 

[AK Hunter]

I will be starting out with 350 Legend and eventually moving on to 223. Sounds pretty straight forward.

Wow! 350 Legend can be a little tricky because they load like long pistol rounds or at least mine does. I load some with 9mm 147gr rounds

& some with 35 caliber 170 gr.

My semi-auto gun distorts the soft cast bullets & they fly everywhere.

Just a thing about reloading any caliber for the AR don't worry about the small dents or nicks in the case they will come out the next time you fire the round. The ARs seam to always dent or put nicks in the cases.

 

[brewer12345]

Wow! 350 Legend can be a little tricky because they load like long pistol rounds or at least mine does. I load some with 9mm 147gr rounds
View attachment 1026006
& some with 35 caliber 170 gr.
View attachment 1026007
My semi-auto gun distorts the soft cast bullets & they fly everywhere.

Just a thing about reloading any caliber for the AR don't worry about the small dents or nicks in the case they will come out the next time you fire the round. The ARs seam to always dent or put nicks in the cases.

Mind sharing your load for the 147s?

The cast I just use in the bolt action. I custom ordered a 180 grain plain based mold and worked up a lower powered short range load for hunting muskrat and beaver

 

[Varminterror]

Loading for a gas operated autoloading rifle traditionally requires 'faster' powders than using the same cartridge in a bolt gun.

Most AR’s don’t have operating rods to bend.

 

[Skeptic13]

The 223 and 308 rounds that I load all use standard primers and I use those rounds in both AR platforms as well as bolt action rifles interchangeably. The only thing I can think of that has not already been mentioned is that I wouldn't neck size only a round fired out of an AR. I don't neck size anyway so this is not a problem for me but some do.

 

[MEHavey]

Already load 350 with a cast bullet for the bolt gun.

Legend/cast in a gas gun is a whole new ball game.....


https://castboolits.gunloads.com/sh...e-350-Legend&p=4996332&viewfull=1#post4996332
https://castboolits.gunloads.com/sh...Cast-Boolits&p=4967562&viewfull=1#post4967562


.

 

[edwardware]

Other than needing a harder primer and making sure the bullets won't move. . .

Yes, there is.
- You're first point is mistaken; use the same primers as usual, seated below flush.
- Reliability may benefit from ~0.003-4" bump under chamber, instead of the usual 2, but experiment.
- Small base dies might be necessary, but only if your chamber is unusually snug, or the brass is from a previous chamber that was quite loose.
- Get your neck tension right, and you'll never need a crimp
- Powder selection will be slightly limited around the edges by the gas system requirements.

 

[Archie]

I am hoping to work with 2400, as Hornady publishes data for it and I have a bunch. I want to start making FMJ fodder using RMR's 147 grain truncated cone 9MM bullets as they are about the size and shape of the factory FMJ. Hopefully 2400 will be fast enough to do the job.

I don't think 2400 will serve very well. Check with a reloading manual - the Lyman #50 does not list it - for the proper burning rate for powders. 2400 burns too fast, and the burn of a case full will be far too much pressure, while a small amount, while safe, does not provide as much pressure to propel the bullet.

 

[Tirod]

NATO standard is a harder primer, the firing pin can and will leave a mark on the primer chambering the round. This isn't a major issue until you get into specialty alternative cartridges - like, .458 SOCOM - which have exhibited the tendency to initiate the primer when you hand feed a round into the chamber and drop the bolt carrier.

Not something a bolt gun has a propensity to do, dynamic loading of the round has rules.

Another NATO standard is crimped rounds to keep the bullets from getting hammered back by the bolt carrier ramming the round into the chamber. Backset is a known issue with soft neck tension, which as we know compresses the load and that has bad consequences. The AR is first and foremost a MILITARY self loading action, and most of what we know about rifles are manual action. The AR functions differently because of it and previous assumptions about how it works based on a lever or bolt gun are often mistaken. They are NOT the same.

Hence the recommendations to use soft civilian primers and not keep the neck tension up to prevent setback. While it may be claimed that the NATO standard is "overkill" for use in a harsh working environment, for the most part issues are extremely rare for the millions of rounds shot annually in practice or in combat. The reports in gun forums however, are plentiful with lots of issues from deviating from those standards. The choice of powder alone described above isn't atypical - it's a dynamic loading weapon which uses gas pressure to operate the bolt carrier and substitutions with bolt gun powders and reloading techniques can and will alter the operating window which will create problems.

Stick to AR powders and the specific techniques, it works fine. Reloading for the AR is not pick from whatever you like, tho, and should be carefully observed to prevent creating issues it was never intended to work under.

 

[Charlie98]

- You're first point is mistaken; use the same primers as usual, seated below flush.

You beat me to it.

The key to preventing slamfires is making sure the primer... any primer... is seated at or below flush with the case head. Many people use standard primers in autoloaders (with floating firing pins,) I have, they work fine, but 1) you may have to uniform the primer pockets to make sure the primer is seated properly, and 2) your rifle needs to be clean and serviceable to prevent the firing pin from sticking, or protruding too far to prevent a slamfire. Arsenal primers are not a bad practice, it's what I use mostly, but the real solution is primer seating.

 

[brewer12345]

I don't think 2400 will serve very well. Check with a reloading manual - the Lyman #50 does not list it - for the proper burning rate for powders. 2400 burns too fast, and the burn of a case full will be far too much pressure, while a small amount, while safe, does not provide as much pressure to propel the bullet.

Hornady lists 2400 data for 350 in it's latest edition and the burn rate is just a bit faster than lil gun. I don't need max velocity out of a fmj round, so I suspect I will find something that works the action. We'll have to see about velocity. I will likely pick a different powder for a hunting load.

 

[Archie]

Brewer, I was talking about the .223 Rem and didn't specify. You are correct, I'd think. The .350 is a straight sided case and expansion ratio is much more abrupt - greater - than a bottle necked .22.
At the same time, the .350 to my mind - I don't load for it or shoot it at all - has greater powder capacity so a full case of the .350 cartridge might require a slower powder to not overpressure things. Check and see if the loadings shown for 2400 are as fast as some of the others.

 

[Archie]

Most AR’s don’t have operating rods to bend.

Bending operating rods - notably in the M1 Garand - is not the only problem deriving from too enthusiastic operation of a semi-automatic arm. There are a number of other parts and connectors which will fail from breakage or accelerated wear.
You are correct, of course. The original design does not have an operating rod. It blows the propellent gases through the bolt. Self-dirtying.

 

[brewer12345]

Brewer, I was talking about the .223 Rem and didn't specify. You are correct, I'd think. The .350 is a straight sided case and expansion ratio is much more abrupt - greater - than a bottle necked .22.
At the same time, the .350 to my mind - I don't load for it or shoot it at all - has greater powder capacity so a full case of the .350 cartridge might require a slower powder to not overpressure things. Check and see if the loadings shown for 2400 are as fast as some of the others.

When I get to 223, I was planning on working with varget.

2400 in 350 has slightly slower speeds for a full weight hunting bullet. Since I will be using a somewhat lighter fmj and don't need it to be all that it can be, I am fine with it. Will likely try lil gun for the heavier hunting bullets unless I run across a pound of something else for this cartridge that I don't already have.

 

[EricBu]

I load a lot of AR rounds, in a few calibers, and one boomer (50 Beowulf). Played with 450 BM as well. With 5.56, and .308, some guns have issues with standard dies, hence the small base die sets you see out there. Plenty of guys run standard dies with no problems.......and some guys just can't get their guns to run without it. 350 Legend will be very similar to 50 BW, you're gonna basically treat that has a handgun cartridge for all intents and purposes. Minimize your belling, and taper crimp just enough to take the bell out. If you use cast, coated cast, or plated, use enough bell enough not to score the bullet......if you use boat tail type...you can get away with no flare. The boomers are particularly sensitive to OAL. The traditional mag length is not necessarily going to apply. The 350 legend is supposed to be much more forgiving, but be prepared to face the possibility that you may have to change your bolt load to run in the AR....or have two different loads. I'm not sure what the common primer for 350 Legend is, or what it was designed for. In 50 BW, I run large pistol magnum primers, in 300 BLK and 5.56 I run small rifle magnum. I've shot literally thousands of rounds through AR's with standard small rifle primers, but years ago I switched to magnum just because then I could store just one type of small rifle primer, and I run that in everything that uses small rifle. Case length and trimming...think pistol. My Beowulf cases ***shrink***. The webbing above the rim collapses over time, causing them to shrink and become shorter, they never get longer. After about 10 firings, the primer pocket starts to get sloppy too...they never get trimmed, they never crack, they never separate, no other signs of wear....when the primer go/no go gauge fails for stretched pocket, they go in the recycle barrel. Don't know if 350 Legend will behave the same, but something to keep in mind. With the BW case, because it's rebated to the 7.62x39 rim, there is a lot of stress at that point, the legend looks a lot more robust in that area. Even so, I suspect it won't grow much. 5.56 on the other hand....you'll need to keep an eye on those, and trim when needed. If you're converting mil brass, you'll need a swager/cutter, and you really should get a primer pocket go/nogo gauge, saves a lot of pain over the years.