.223 Rem 75gr A-Max question

[Legionnaire]

I'm looking to develop a .223 Remington load for my Tikka T3 using Hornady's 75 BT A-Max bullet pushed by Varget, since I have a lot of the latter. Various data sources list max loads in the 25.0 to 25.6 range:

Lee's "Modern Reloading" shows 25.0 grains at 2907 fps for a 75 grain bullet.
Hodgdon also shows 25.0 grains at 2907 for a 75 grain bullet.
Lyman #49 shows 25.6 grains at 2843 fps for a 75 grain bullet.

However, Hornady's own manual shows a max load of 23.5 grains of Varget behind the 75 grain A-Max at only 2600 fps.

Why the discrepancy? I am aware that the A-Max is a long bullet that needs to be seated longer than the standard 2.250" COAL. Hornady's manual shows a COAL of 2.390". Nevertheless, 23.5 grains of Varget seems well below the other max loads listed. Could it be that the 23.5 grain load is max for the AR15 (service rifle) platform, and 25.0 would be fine in a bolt action?


Thoughts?

 

[rcmodel]

Different test guns.
Different test conditions.
In addition to that:
Hodgdon is using a different brand of 75 grain bullet.
Lee doesn't bother to say what brand they used.

And Hornady has always been somewhat known for consertive load data.

I would trust the Lyman manual to not steer you too far wrong.

rc

 

[Legionnaire]

Okay. Just spent some time at the loading bench. The A-Max bullet measures 1.108" (compared to the JLK VLD that measures 1.050"). Just to check case fill I loaded the following under the A-Max with a COAL of 2.390" (too long for the magazine):

23.5 grains Varget had room to spare; can hear loose powder under bullet.
23.7 grains also had room to spare, but less; can still hear loose powder.
At 23.9 grains, you can hear the bullet crunch into the powder when seating; the powder will settle, and you can still hear it shake.

I stopped there. I think 24.1 grains would probably begin to compress.

I also loaded 25.0 grains of Varget into a case (without a bullet) to see what it looked like. Filled the case up to the top of the shoulder. No way a 1.108" bullet is going in there without compression.

So I loaded up a few "sighters" at 21.4, 21.8, and 22.2 grains, then sets of four rounds each in .2 grain increments from 22.5 to 23.9 grains. Off to the range tomorrow to see if I can find a sweet spot.

 

[Hondo 60]

Looking forward to your range report.

 

[GooseGestapo]

The Lee data is the Hodgdon data reprinted under license.

The bullet is most likely the Hornady, the difference in the other data is due to different barrels made by different mfg's, and almost assuredly a different Lot# of powder.

Case mfg, and lot# as well as primers can make such difference, too.

Hence the admonition to start 10% below recommended max, and work up to what your rifle wants/tolerates.

 

[Legionnaire]

Range trip postponed until Friday ...

 

[rhubarb]

Varget compresses at relatively low charge weights. My best 223 loads have been with compressed Varget.

Lyman #48 shows separate loadings for 75 BTHP compared to 75 Amax. The Amax shows 0.6 grain more max than the BTHP due to being loaded longer. Some others don't specify Amax which of course is a much different bullet from most BTHP.

I haven't had any Varget for a while, but I shot some 75 Amax in my 1:7 AR this week with the best results above 2800 fps. My Oehler and my batch of RL15 agree with Lyman's listed velocities.

 

[kelbro]

Make sure that you use the Hornady recommended OAL measurement for that bullet (magazine dependent). If seated to 2.25, yes a lot of the shank is below the neck/shoulder junction and you will not realize the full potential of that bullet/powder combination.

 

[Legionnaire]

Range Report

Well, had several hours at the range today. Shot eight different three-shot groups following Don Newberry's optimal charge weight (OCW) instructions. I was disappointed.

Observations:
1. No signs of pressure at the high end of the range: 23.9 grains.
2. The eight groups averaged 1.719" and ranged from 0.968 to 2.564 (I suspect a flyer in the latter).
3. The three best groups averaged 1.208". Okay, but nothing to write home about.

I felt good about my technique, and my fouling shots (factory loads) grouped better, so I was pretty sure neither the gun nor I was the problem. So back home and loaded up another 25 rounds, this time with Sierra 60 grain HPs. Stuck with Varget and loaded five sets of five rounds at 23.4, 23.8, 24.2, 24.6 and 25.0 grains. Didn't bother with the OCW "round robin," just shot five groups at each charge weight.

Observations:
1. Again, no signs of high pressure at 25.0 grains.
2. The five five-shot groups averaged right at 1.010". Much better.
3. The second and third groups opened to 1.560 and 1.225 respectively, and the other three were all sub-MOA, the best measuring 0.668".
4. Three best groups averaged 0.756.

Conclusions:
1. Still have room on the high end with both loads.
2. My rifle doesn't like the 75 grain A-max bullets, or at least doesn't like Varget pushing them.
3. The Sierra HPs show a lot of promise as the last three groups dropped from 1.225 to 0.786 to 0.668.
4. I need to run the Sierra load up a bit higher--watching for pressure, of course--to see if the groups will shrink further.
5. The OCW "round robin" is a pain. I'll probably simply stick with shooting individual groups in the future.

Comments welcome. Always willing to learn from others who have been at this longer than I.

 

[ForneyRider]

Try 69 and 77gr SMK's or Nosler CC. I am assuming this is the 1:8tw T3, not the 1:12 model.

 

[Legionnaire]

Yup, 1:8.

 

[REL1203]

So i just picked up a 100 pack of 75g AMAXs at my local show yesterday, pretty good price. Anyway, is there a reason in the Hornady book, they dont list the 75g in the regular 223 section (they only list it in the Service Rifle section)? i planned on shooting this in my Rem 700 just to see, and use it in my 1:7 Daniel Defense M4.... Any ideas? SHould i just use the charges listed for the service rifle for both?

Is the 75Amax a bad choice for the M4 with it not fitting at 2.390" COAL into a PMAG?

 

[Legionnaire]

From what I understand, the "regular" section in the Hornady manual applies mostly to lighter bullets and rifles with slow(er) twist rates. The A-Max requires a fast twist (1:8 or faster?) to stabilize. And with its long COAL, the A-Max is a load-one fire-one proposition, even in my bolt-action Tikka.

 

[ForneyRider]

75gr A-Max is not for AR-15 magazine loading. It is for single feeding.

You can load the 77gr SMK or 75gr Hornady BTHP to magazine length.

 

[45Badger]

Amy suggested bullets for a 26" 1/9 twist Remington 700?

 

[ForneyRider]

Lyman book has max of 25.6gr of Varget for 75gr A-Max.

Try 50-55gr Target or Varmint bullet, and a 68-69gr Target bullet. Varget should work with either.

I haven't tried the 75gr Amax in my 1:9tw DPMS AR. I can hit .6in group with 75gr BTHP and 69gr SMK. I got .488in group with 52gr SMK. These are 5 shot groups. My 3 shot best is in the 3's and 4's.

I see online a lot of people shooting 75gr Amax and 77gr SMK in 1:9tw with good accuracy. I just picked up 50cnt box of 77gr SMK to try. My latest 73gr Bergers have been loaded for months, but haven't had an opportunity to shoot.