Do you use a taper crimp on your AR-15 .223 ammo?

[ShtrRdy]

I dug out the target/varmint AR to see if I could get the Hornady 60 grain V-max to shoot well out of it. I loaded up some cartridges for an "Audette velocity ladder" test as a starting point. I set the COAL to magazine length of 2.250". Using H4895 I loaded up 8 cartridges with powder weight increase of 0.2 grains per step. With a Magnetospeed hanging on the barrel I fired three on one aiming point, three on another aiming point, and two on a final aiming point. The first 6 shots combined were about 0.3" at 100 yards. The last two shots were moving away from the first six. Even though I was single feeding these I applied a taper crimp to the neck when I assembled them.

For a next step I loaded five cartridges with a charge weight that had a similar velocity, ( ~ 3005 fps ), and were within 0.2" of each other from before. The plan was to fire 2 over the chrono and 3 for a group. The first two rounds over the chrono were 3005 & 3065. The first one was as expected but why was the second shot so much higher? The 3-shot group was disappointing at 0.467" at 100 yards. I applied a crimp to these as well but i don't have a way to know if this amount of crimp was similar to the first group.

Is it possible my crimping step is causing a large difference in the way the interior Ballistics behave?

Do you apply a crimp to your AR-15 rounds?

Lapua brass
Hornady 60 gr V-max
CCI small rifle prime
24.9 gr H4895
COAL = 2.250"

 

[jasonco]

I load almost all my AR ammunition on a progressive & a semi-progressive and I do crimp, for no reason in particular other that taper crimp die is installed in the turrets.

Great accuracy and no wild ballistic swings, in a 24" bull AR to a 18"SPR, 14.5" to 10.5".

 

[asd9055]

I load almost all my AR ammunition on a progressive & a semi-progressive and I do crimp, for no reason in particular other that taper crimp die is installed in the turrets.

Great accuracy and no wild ballistic swings, in a 24" bull AR to a 18"SPR, 14.5" to 10.5".

Jason what od you load for your 24" bull barrel if you don't mind

 

[nhhunter]

I use the Lee factory crimp on all my ar loads nothing heavy just little bump

 

[xsn10s]

I don't crimp my AR15 loads, but I do test them for COAL movement after feeding into the AR. I do that at home with a "push test" on a table top and then at the range by measuring after feeding from the magazine. On a taper crimp I'd want all my cases to be the same length since the taper crimp is dependent on case length. I'd also make sure all my cases were chamfered and deburred. If I were to do a crimp I'd opt for a Lee Factory crimp. I've used those on and off since I read a suggestion from Ken Waters back in the 80's. Sometimes the Lee Factory crimp improves ES/ SD and accuracy. I can only guess that it improves consistent neck tension that improves ignition/ burn.

 

[Cemetery21]

I don't crimp my AR15 loads or any bottleneck cartridges, but I've only been loading since the early 1970s.
I would crimp into a cannelure if I ever loaded for a tube fed rifle.

 

[AllenRay]

I use the Lee factory crimp on all my ar loads nothing heavy just little bump

I do this.

 

[BHP9]

I use an RCBS small base sizing die and a Bonanza Benchrest Seating die, no crimp, and have had no issues.

 

[backwoodsshooter]

I use the Lee factory crimp on all my ar loads nothing heavy just little bump

I do this as well

 

[30BR]

I use an RCBS small base sizing die and a Bonanza Benchrest Seating die, no crimp, and have had no issues.

Over time do you find the SB sizer overworks that area? Do your primer cups loosen up? Asking because I am considering a SB sizer for a competition gun…

 

[BHP9]

Over time do you find the SB sizer overworks that area? Do your primer cups loosen up? Asking because I am considering a SB sizer for a competition gun…

I don't anneal, I'm 14 and 15 reloads on a batch of Norma 308 without issues with loose primer pockets or the brass hardening. All of my 308 loads are SB sized for every rifle.

With the 223, I have a batch of fully prepped brass that are on load #8 (IIRC), but I do get some loose primer pockets and that brass goes into the scrap bin. All of my 223/556 brass is SB sized.

 

[436]

I dug out the target/varmint AR to see if I could get the Hornady 60 grain V-max to shoot well out of it. I loaded up some cartridges for an "Audette velocity ladder" test as a starting point. I set the COAL to magazine length of 2.250". Using H4895 I loaded up 8 cartridges with powder weight increase of 0.2 grains per step. With a Magnetospeed hanging on the barrel I fired three on one aiming point, three on another aiming point, and two on a final aiming point. The first 6 shots combined were about 0.3" at 100 yards. The last two shots were moving away from the first six. Even though I was single feeding these I applied a taper crimp to the neck when I assembled them.

For a next step I loaded five cartridges with a charge weight that had a similar velocity, ( ~ 3005 fps ), and were within 0.2" of each other from before. The plan was to fire 2 over the chrono and 3 for a group. The first two rounds over the chrono were 3005 & 3065. The first one was as expected but why was the second shot so much higher? The 3-shot group was disappointing at 0.467" at 100 yards. I applied a crimp to these as well but i don't have a way to know if this amount of crimp was similar to the first group.

Is it possible my crimping step is causing a large difference in the way the interior Ballistics behave?

Do you apply a crimp to your AR-15 rounds?

Lapua brass
Hornady 60 gr V-max
CCI small rifle prime
24.9 gr H4895
COAL = 2.250"

Yes, I apply crimp to almost all of my AR rounds mainly the ones that have a cannelure like my M262- Mod1 77gr OTM clone, for those that don't I still use a cannelure, but I use a very light crimp on them with a LEE Crimp Die... bolt guns are pretty much always tapper crimp, a few I'll crimp now and them. Actually, the LEE Crimp Die seems to improve accuracy in my rifles, maybe it's bringing the case and bullet into more of a concentric line? My concentricity case gauge tool seems to think so most of the time, and the LEE gives a loader very consistent neck pressure I think. Maybe I'm wrong just my 0.2

As for your crimping; are you using a factory roll crimp die? yeah, I think that could cause a problem, I only use roll crimps on my revolvers cartridges.

Cheers

 

[ShtrRdy]

Yes, I apply crimp to almost all of my AR rounds mainly the ones that have a cannelure like my M262- Mod1 77gr OTM clone, for those that don't I still use a cannelure, but I use a very light crimp on them with a LEE Crimp Die... bolt guns are pretty much always tapper crimp, a few I'll crimp now and them. Actually, the LEE Crimp Die seems to improve accuracy in my rifles, maybe it's bringing the case and bullet into more of a concentric line? My concentricity case gauge tool seems to think so most of the time, and the LEE gives a loader very consistent neck pressure I think. Maybe I'm wrong just my 0.2

As for your crimping; are you using a factory roll crimp die? yeah, I think that could cause a problem, I only use roll crimps on my revolvers cartridges.

Cheers

Thanks for sharing your thoughts and experiences. I'm using a Redding taper crimp die. But I don't see how I adjust the die for the same amount of crimp from one reloading session to the next.

edit note: corrected die brand

 

[436]

Thanks for sharing your thoughts and experiences. I'm using a LE Wilson taper crimp die. But I don't see how I adjust the die for the same amount of crimp from one reloading session to the next.

You might look into LEE Crimp Die... Your die is a taper crimp, so it's a taper crimp only? it's not going to roll or factory crimp right. Most die that crimp adjusts by moving the die depth up and down in the press.
I looked for "LE Wilson taper crimp die" from your description on Wilson, but I couldn't find one.? Cheers