Time to load for the ARs... need help

As has been said, you need to figure out what you want to do, then adjust the load accordingly. I build loads differently between my AR and my 700SPS. My AR is mostly my "blasting" rifle, so I don't get to worked up about having super accurate loads. That said, here's my experiences with loading for my AR:

The biggest cost always seems to be the bullet itself, I wouldn't get to hung up on the cost of powder.

For my AR I've used IMR 4895, IMR 4064, BL-C2, Varget, and now H4895. I've liked them all. The BL-C2 meters the best IMHO.

Right now I have a lot of H4895, so that is what I'm using for the time being. Projectile wise, I mostly run the 55gr CamPro bullets. They are a good price and seem to work well for me.

I full length size and trim all brass to 1.750". Seat the bullets to 2.25" OAL. Right now I've got a bunch of bullets that are 24.5gr of H4895 pushing a 55gr CamPro to around 2750fps. Next batch I load will probably have a bit more powder to it, maybe 25.3gr or so (26gr is about the max for H4895 and a 55gr bullet)I have had sub MOA groups with this load, although somewhere around 1.5MOA seems to be more common.

I crimp, but not for accuracy - it's to ensure the bullet stays in the brass. I don't trust the neck tension to hold the bullet in place.
 
Very important that any reloader for any semi auto checks, checks and checks again to ensure the safe function of their ammo.

So how do you do that. For me, I make up 5 to 8 dummy rds... no powder, nor primer but sized and bullet seated as I would use in the rifle. Measure the OAL of each case and mark them so you can identify them later.

Load up in a mag, pull the charging handle back and let fly. Eject the case... I like to do this next to a pillow or couch so the flying cartridge isn't going to hit something hard and change the OAL. Redo a minimum of 5 times measuring the OAL each time. Was there a change in OAL or were there any obvious marks, cuts or lines on the bullet tip, either fix the feeding or crimp the ammo.

If the cartridges have passed this test without changing their OAL, I make up another batch. These I will load into the 4th to 6th round in a mag and be fed into the rifle while shooting. Cycle out and check OAL and any signs of nose damage. Again, after 5 cycles through the rifle nothing changes, then you don't need to crimp for this particular rifle/mag set up AND the neck tension is obviously enough to hold the bullet in place.

This is not a question a reloader asks on a forum... it is something they test and test for EVERY MAG they will use... and for every bullet they will use.

Another big reason to complete this test is to ensure the cycling is not damaging the ammo itself. For those trying to maximise accuracy or competing, having their ammo banged up and bent when feeding is not going to give you small groups or high scores.

WRT to accuracy, when I say my testing with crimping showed no benefit, I am looking at rifle and ammo that will average sub MOA... 1/2 to 2/3 MOA over many 5 rds groups... not one hero group or better yet, best 4 out of 5 shots on target. See the CGN AR sub MOA challenge for an idea of what I mean.

If an AR is only averaging 1.5 to 2MOA, which is the vast majority of rifles, many of the steps used in precision reloading will be of little advantage cause the system isn't accurate enough to see the benefits. And it would be very reasonable to expect that crimping would not change the outcome.

NOTE: when I am talking about crimping and accuracy, I am discussing bullets w/o a canneleure. A Lee FCD can squish the bullet enough to leave a waist. The Redding taper crimp die might be more gentle on the bullet but I don't see how it can make the bullet pull higher unless the neck is pushed into the bullet some how (what happens with taper crimped HG ammo). Distorting bullets will not help them fly better.

YMMV.

Jerry
 
Crimping isn't to ensure your OAL doesn't change slightly upon loading, and doing a test on dummy rounds hand cycling them through the action is completely missing the point.
Crimping is to ensure each round feeds reliably into the chamber without induced bullet setback.
Bullet setback can happen on every single round that gets chambered, if it isn't crimped whether your gun is running right or not.
Sometimes the bullet setback can be minimum or sometimes it can be extreme and (hopefully for the shooter) cause a stoppage.

If you've never experienced it, be it in an auto loader in general or an AR specifically, you probably haven't been shooting these types of rifles for very long.


With respect to the accuracy aspect: I don't crimp for accuracy, I crimp for reliability; it just doesn't have the degradation to accuracy as some would have us believe.
The 'damage' suffered by the bullet without a cannelure is totally dependant on the tool and technique used. It can be done lightly, and with minimal I act to the bullet. Shown is a Hornady 75gr. HPBT that has the crimp indenting into the jacket less than the depth that the rifling is going to make as it gets sent down the barrel at 2700 ft/sec.





10 rounds at 700m through a 24" long Lilja barrelled AR prone off the mag. Sorry, I don't have a collection of benched 100m 5 round groups....
 
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That first picture has certainly failed both tests :)

OAL has changed... and there is significant nose damage on the bullet.

Cycling test cartridges through the rifle multiple times either manually and/or while firing IS a reliable way to test the feeding of any semi. Now if a shooter is not comfy with the end result, then by all means, take any and all steps to ensure safety and the safe operation of the firearm.

Brass will only offer so much grip on a bullet. if you size a case neck 3 to 4 thou smaller then bullet diameter, that's it.... it can't grip anymore. So crimping is introduced as a mechanical "stop".

If a crimp is applied so light that there is no distortion of the bullet, it really didn't do anymore then what the case neck could in the first place. The ammo may have entered a die but the end result didn't change.

If the neck is squeezed into the bullet enough to cause some deformation, then a true mechanical lock is added and most certainly does help.

Does it affect your accuracy? Only the reloader can prove the point in their rifle, their ammo, their performance goals.

YMMV.

Jerry
 
aric84 said:
My service rifle load that has worked well for me, as always double check the data:

69gr SMK
BLC2 powder 24.5gr
IVI brass
2.260 OAL
CCI small rifle primer
Light crimp with Lee factory crimp die

Produces 2650fps in my 20"1/7 Stag arms model 4 and the hold overs on my Elcan spectre DR match up perfectly out to 500m

Only ever used the regular RCBS dies and never had a stoppage in a couple thousand rounds. Nice gentle recoil impulse as well, not snappy feeling.
Click to expand...

I like BLC(2) for bulk reloads because it meters very reliably, but I find it is rather temperature sensitive, so I've changed over to Varget.
 
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