Mag length..???

[Rsadams]

Working on my first .223 69gr SMK loads and book wants a COAL of 2.260.... That seems to be right at mag length for Magpul mags... I only loaded 5 to speed test tomorrow.... What are you guys loading for COAL on that load and will it cause mag jams with a fully loaded mag in your experience at 2.260.... I was thinking of pulling them back to 2.250 just to be safe on my next round....

 

[K Simmons]

Working on my first .223 69gr SMK loads and book wants a COAL of 2.260.... That seems to be right at mag length for Magpul mags... I only loaded 5 to speed test tomorrow.... What are you guys loading for COAL on that load and will it cause mag jams with a fully loaded mag in your experience at 2.260.... I was thinking of pulling them back to 2.250 just to be safe on my next round....

I load 77's both sierra SMK's and Noslers to a COAL right at 2.260. Using magpul mags, never had an issue.

 

[Jeff Porter]

FWIW- longer isn’t always better. I have found 69 SMK shoot better in my Wylde chamber at 2.240”. With the short nose profile of 69 and lighter bullets..I have found some will be touching or even jammed in a 223 chamber at 2.260”.

I will run a jump test of sorts with my mag fed ammo. Start at 2.260” and shoot 5 shots at 0.005” increments back to 2.235”. One will be tighter and rounder group

 

[joshb]

The last time I loaded a 1k batch of “plinking ammo”, I think I gathered all my magazines together and checked them with a dummy round. It’s been a while but they may have been a little short. Just figure out your best length and test at that for your best powder charge. It gets a little complicated when you’re trying to find a good load for three different ARs. Leave your finicky 1/2” group thoughts at the door.

 

[Zero333]

69 smk doesn't really care about how close to the lands you loads it.
From my very amazingly short memory I think i use 25 gr of Varget around 2.290" COAL ( 0.010" jump")
I also have a MDT chassis for another 223 with a 2.450" Magazine and I still load them at 2.990" and they shoot no better or worst than in the shorter mag at 2.990".

 

[JB10]

All my 223 AR loads i set at 2.250 for just that extra clearance. For all my bolt actions i do at least 2.260 and one of them i load way longer to be close to the throat and the blind mag in that one lets me do it.

 

[Metal God]

Load them to 2.255 this will insure they all cycle . SMK’s are known to have very inconsistent base to tip measurements. I did a test on a box of 77’s and there was an ES of .008 variance . So if you are unlucky enough to use one of the shorter bullets as your test cartridge there will be some that will hang up in the mag . Learned that little gem the hard way years ago . The polymer tipped bullets tend to be more consistent but SMK are not . There base to ogive is good but base to tip , not so much .

 

[Gargoyle]

77 SMKs 2.250"

 

[Rsadams]

Load them to 2.255 this will insure they all cycle . SMK’s are known to have very inconsistent base to tip measurements. I did a test on a box of 77’s and there was an ES of .008 variance . So if you are unlucky enough to use one of the shorter bullets as your test cartridge there will be some that will hang up in the mag . Learned that little gem the hard way years ago . The polymer tipped bullets tend to be more consistent but SMK are not . There base to ogive is good but base to tip , not so much .

They are crazy all over the place..

 

[Walt Krafft]

Load them at 2.250. Failure to feed is a way bigger problem than any loss in accuracy, which their probably won't be.

 

[Metal God]

Yeah 2.250 is likely better

 

[Doom]

The problem with 2.260 is making sure you don't exceed that length due to bullet variations. Because the bullet seater is not working off the point you need to be sure you are within what the mag can handle. I load my 77 NCC's to an average of 2.255"(corresponding CBTO dimension) to keep the max COAL at 2.260".

 

[Firearmsunlimited]

The problem with 2.260 is making sure you don't exceed that length due to bullet variations. Because the bullet seater is not working off the point you need to be sure you are within what the mag can handle. I load my 77 NCC's to an average of 2.255"(corresponding CBTO dimension) to keep the max COAL at 2.260".

Absolutely correct!

 

[arlaunch]

Measure each and every bullet in your bullet box. And then the next bullet box.

Note the measurement of the longest one in your notes.

Save the longest one also just for reference.

There will likely be a duplicate of that one. Or several. Expect .020 variance in a box of 500

Set your die up with the longest one. Set that bullet to be at 2.250 - 2.260 depending on your comfort level.

If down the road you get a new box and find one longer, you can extrapolate on your die setting. Or just set your die for the new longest one.

If you are running a compressed load you could end up having the bullets pop back out and be too long.

Take this stuff into consideration when you pick your COAL.

Spend a bit time doing this in the beginning, save tons of time as the years go by.

 

[Richard Jones]

Just FYI, the stainless ASC AR mags will allow me to go to 2.300, and they feed fine. I use them in my 6x45 for just a bit more room with the heavier bullets, although it probably means very little.

Just throwing it out there.