.223 vmax loaded and shot data

[marine0341]

I am shooting a M4 Bushmaster .223/5.56 semi auto 1/9twist

I loaded .223 55grain vmax with 5 rounds 18grains, 5rounds 19grains and 5rounds 20grains of IMR 4198


The first load of 18grain was a high group at 50yards
the 19grain group droped for 2 inches.
The last load of 20grains was grouped closer to the center but not dead on.

My question is, is the drop in groups consistent with the increase of pwder charge?
Why was the majority of my brass jamming. I had to extract and reload the mag for every shot? Maybe my mag is a peice of garbage or maybe I should increase my COL.

Any advice or tips would be appreciated . I am new to this.
Thanks guys.

[steve4102]

More details please. 18 grains of what?

[steve4102]

Oh, I see you high lighted Hodgdon, what Hodgdon powder are you using?

[Oberg]

Maybe cuz the trajectory is flattening out? But that is just my guess. Maybe someone with more intellegence then I can confirm or disregard my thoughts

[marine0341]

All loads were shot at the same range 50 yards

I understand my group would move up from were I zero it out at but I am looking for the reasoning behind changes pwder and its effect on the bullet group

[wpcexpert]

First, every powder charge (no matter how small a difference) will more than likely change your bullet impact point. That's just the rules. You can increase the powder charge and the bullet could drop, you can decrease it and the bullet could could rise, or go to the left or right. It has to do with your barrels harmonics.

Short answer, when you fire a gun, the barrel vibrates. It's vibrating when the bullet exits the barrel. So with every different powder charge, the bullet is going to be exiting the barrel with a different vibration.

You shouldn't even be worrying about bullet impact at this point. You should be looking at group size, and how you cases look after the shot. After you find a load that groups good enough for your standards, then worry about adjusting the sights.

As far as you sticking cases,
- Are you full legnth sizing or neck sizing?
- Are the cases fired from your rifle or someone elses?

Need more info. Was the rifle not cycling? Would the bolt lock back like there was an empty magazine?

[Qtiphky]

You still haven't told us what type of Hodgdon powder you're using. Varget, Bencmark, etc. . . I'm more curious about the jamming problem at this point. Did you full length size the brass? Was it new brass or found on a range? Was it previously fired from your weapon, even if it was, with an autoloader you should still full length size it. What is the overall length of your loaded rounds? Something is causing the jamming problem and that could cause problems with accuracy, pressure, etc. . . I read somewhere else that this type of phenomenon is normal when looking for the sweet spot for your gun and three shot groups aren't in and of themselves completley proper. You should do many three shot groups and then take the average spread to calculate the relative accuracy of the load. Then sight the weapon to hit where you want it to hit.

[oryx]

If your gun keeps jamming I would first try a different magazine that you know is good. If you are resizing for a semi Auto you always want to full length size. You should also use a case gauge to set your resizing operation to know that you are resizing to the proper dimensions. You don't want to increase your COAL or your rounds will not fit into the magazine properly or feed properly. Size the OAL to the specifications in your manual

[ZX10Aviator]

glad to see someone else using the same powder as I do in .223, my groups are half the size as varget.. Last great load was 22grains and 52grain bullet, one before that was 18.5gr with a 69HPBT bullet.

[marine0341]

To Answers some questions

The brass that I am reloading has been fired from my gun.

I don't use an auto loader, I do it by hand.


I have the lee die and deprimer that resizes the neck in which I thought was only really needed for the .223

The bolt doesn't lock to rear it simply extracts the fired round and then moves foward into the breech with no round.

My magazines are used but have alway's worked with factory ammo.

My oal is 2.265
55 grain vmax with IMR 4198 powder
CCI # 7 Primer for small rifle
I am shooting a m4a3 bushmaster 1x9 16 inch barrel zeroed to 500 + yards with iron sights.

Ok so the bullet group will drop with higher charges, got it. The jamming issue could be cause of slow bolt retraction due to low pwder charge. So should I change the up my pwder before thinking of changing my OAL.?

[ForneyRider]

I tried neck sizing with Lee collet die and it didn't work in my DPMS AR with .223 chamber. I didn't attempt to fire it. I test loaded it and it wouldn't eject easily, so I failed it. I looked at the brass afterwards, and it was heavily scored.

The rule of thumb is to full-length size on autofeeder gun.

I went with the full length Lee and have no issues.

You can try partial full length, just keep experimenting with more and more sizing until it feeds reliably.

Also heard RCBS X-die works pretty well. RCBS calls it a neck-sizer die, but from the video on their site, it looks like the body is touched. Not sure. I have one of these for 8x57 and it works great, but it is for a bolt action.

19gr is min. charge for 55gr Speer SP. Not sure of the difference between the Speer and the V-Max in size, but that load may be too light for decent accuracy.

[ForneyRider]

Also, one of the reasons why I went with neck sizing any rifle loads was to save on wear and tear on my brass.

After reading more, several people claim 20+ reloads from bottle-neck brass that was full-length resized. These were brass that were used with full power loads at that.