Ogive and an AR

[aviumvenator]

For those that load for a DMR type magazine feed AR did you test different OAL’s as well?

I am new to reloading for the .223 and after reading and talking to those more experienced than me I understand the importance of measuring off the ogive for seating bullets. The load I am working on is with a 75g HPBT, cci 450, and A2520. The load data from Accurate lists the OAL as 2.260. When I zero in on my load and want to test OAL I am limited to only decreasing it due to the magazine. I have not measured the distance to the lands yet.

The rifle is a Barnes Precision 18” with a Wylde chamber and I’m using it for DMR matches and predator control.

Thanks...

 

[adam3999]

Re: Ogive and an AR

Sure, people experiment with different COALs in AR-style rifles. As you mentioned, you will likely be constrained by the magazine depth, however. You may want to back off 0.010 or 0.020" more for reliable feeding, even. Depends on your chamber but generally AR lands start pretty deep, so you may not even be able to touch it with the longest suitable COAL for your magazine. You'll have to either single load, or find a suitable primer/powder/bullet combination for a shorter COAL.

For bolt guns, I measure by setting a new bullet into a once-fired case. If you search through a few pieces of brass you can usually find one that holds the bullet with moderate tension. Seat the bullet long, chamber it, carefully remove it, and measure. Rinse, and repeat for an average measurement. This is a lot harder with a gas gun since chambering/extraction are violent. Try these two products.

 

[BlkExp98]

Re: Ogive and an AR

I have one of the Hornady tools and I have had pretty consistant results from it. In my case I found the below info with my WOA Varmint barrel in .223. Some 75Gr. Hornady TAP I measured the OAL of came to right about 2.250" to the bullet tip and it was getting pretty close to the end of the magazine. Another 10 thousanths would be getting pretty snug I would think. I've thought about getting one of the sleds they call them for an old 20rnd magazine to single feed longer loads but I havent yet. If you havent seen them it basically just replaces the follower with a guide for a single round. I dont know if that would be legal in your match though.

<span style="font-style: italic">The following are examples of the seating depth to the lands on MY barrel. We all know this info isnt universal so dont assume its the same on yours. (End of disclaimer

)</span>

<span style="font-weight: bold">-77 Gr SMK </span>
1.913" to the ogive
2.319" to bullet tip
<span style="font-weight: bold">-75 Gr. A-Max</span>
1.900" to ogive
2.456" to bullet tip
<span style="font-weight: bold">-69 Gr. SMK</span>
1.910" to ogive
2.310" to bullet tip
<span style="font-weight: bold">-60 Gr. V-Max</span>
1.903" to ogive
2.306" to bullet tip