Home Forums Hunting & Shooting AR and Tactical Rifles 75 grain A MAX

Folks,
I've got a 20" 1-7.7 twist VARMATCH barrel ,I guess it's closer to 8 twist than 7 .

I'm wondering if any of youall are shooting this bullet in an AR 15 platform.

Hornady " suggests " a col of 2.380 or 2.390 if don't recall which but it's a long overall length . I'm wondering if anybody has loaded them shorter and how it worked out .
I can understand their reason it's ogive is way back . Maybe you guys know of a different kind of mag or a modification. I appreciate any pros / cons you can pass my way.

Thank you in advance for your time and help.

Semper Fi,
Soup

I loaded a dummy round up to mag length (2.260) and laughed at the results. The 75 A-Max is best to be saved for bolt guns.

With enough neck tension and full powder charges(safe powder charges though) it'll look ugly at 2.250 for the mag length rounds. Ammo must be worked to pressure with that length though, but if worked up at that short length you will be fine.

And for the laugh comment, it is right. I have beaten the snot out of a lot of folks at Camp Perry wiht that laughing load though....

Mag length is better off at 75 bthp... but the amax worked for me just fine for its purposes.

I purchased a box of them about a month ago for my AR, it's built based on an Anderson Lower and 18.5 inch barrel with a Wylde chamber. I worked up to 26 gr of CFE 223, tried a three shot group at 100 yards, the bullets hit all over the place, about a six inch group. I called Hornady and the tech that I talked to told me that due to their length they have to be seated to 2.360 oal and single loaded in ARs because of the magazine length restrictions, 2.260 is the max oal if you are using a magazine in your AR. I gave the rest of them to a friend who has a 223 bolt action. I would try the new Sierra 77 gr tmk bullets, I am getting groups averaging .800 with CFE 223

I love me some 75 A-Max in my 223 Montucky, but for my AR rifles, please pass the 77gr TMK.

I haven't done it but there was some guys cutting the front out of a P-mag from the top down to where the mag well starts to end. Might give it a shot.

Hmmmmm...be an interesting experiment. Pmags are cheap

I did cut mags for 75 JLK VLDs in the late 80s. They work.

But I just had to laugh at the Hornady rep... has NO clue what might work and might not....

Its far from ideal, but it does work.

Can't really see wasting the effort for the incremental advantage of SMK or TMK's at any sane & practical ranges.

Maybe for something very special, but that's stretching.

MM

A-max is world's better than the SMK in both BC and terminal performance and the TMK's were too finicky in my guns.

Sane and practical? What's that?

We be loonies, or not?

I've certainly done a lot more to gain much less...

I use 'em in my Rem 700 bolt guns.........removed the magazine block so them can be seated to kiss.

Better things to do than dink with 'em in modd'ed AR mags or feed 'em singly.

Have it though, ya'll.................

MM

More than a few competitors over some years wished I hadn't monkey'd with em. LOL.

Jeff, at what range did you begin to see an advantage over the SMK's?

MM

I ran them as 300 yard rapid fire, they were heads and tails above the SMKs in wind drift at that range, often we shot 300 with no sighters, 10 down the tube with generally no clue if your guess was right.

If I was shooting them single load, I ran JLKs instead of amax or smks

I could easily see the wind difference in slow fire reduced matches, between 75 amax and 77 smk windage wise. Accuracy wise actually too.

200 yards I saw no difference.

500 and 600 yards definitely a difference, but then if you compared 75 amax to 80 smk there was not enough difference to worry about, but compared to 77s, yes.

I've never fired an amax 75 past 600 yards that I can recall.

TTT

I've cut the front out of P-Mags to shoot the 75gr A-Max. I also use the the same mags for my 6x45 with the 100gr Hornady BTSP.

How much can you increase the OAL, doing that?

Feeding from the magazine at 3.345 with the 100gr Hornady in my 6x45

2.345, I assume you mean? That does seem worthwhile. I bought a few boxes of 75 Amaxs expecting a 1 in 8" single shot, which arrived with a 1 in 9" barrel Be nice if I could run them in the Mk12, at least it has a 1 in 7" barrel.

You got it. Typo on my part.

I don't recall the measurement for sure, but that one sounds about right.... take a mag, use a caliper, measure from the back inside to the front outside...that will about tell you...

Some guys are even filing out the front of the mag well in the lower receiver, to get more OAL in combination with these cutout mags. That's farther than I'm willing to go at this point, but an interesting possibility.

For those who don't know, ASC mags will get you 2.300"+ without any modifications. I still like Pmags better for most things, but you're limited to 2.260" without cutting.

Bump

What answer are you looking for?

Just trying to get as much knowledge as I can .
That's all .
Sorry it annoys you.

Soup

Doesn't annoy me, just thought we were missing something.




Bump...

SMACK,

Check your PM

Soup

I slotted a 10-rd PMAG and with the 75 AMAX seated as deep as I dare, but the receiver on my AR still wouldn't accept it. I could see the receiver mod helping.

The Horny 75 BTHP fits with room to spare compared to the 75 AMAX.

I gave up the 75gr amax after it became obvious I would have to mod mags and receiver to use as a repeater.

Same deal with the .223 Montana, accuracy was only found at a length that would not even eject.

Happily using Hornady 75gr bthp in all .223s now, no mods necessary.

once again... I've used 75 amax at 2.250 with no issues.... but some just tend to ignore experience...

No mag modifications... I used modified mags in the early 90s cut out mags just to run 75 jlks....there was never a need with the amax.

Could you get them up to speed and how was accuracy with that kind of jump?

Speed was enough, out of the mag, that it made a difference in wind drift at 300 yards.. which was the point of my playing.

Accuracy, lets just say I had numerous iron shot rapid fire 10 shot groups where I had 7-8x and the x is 3 inches in diameter.

Actual accuracy with a scope off bags was 10 shots into 1.5 to 2 inches or even a bit less at times depending on the particular barrel, at 300 yards.

IIRC the powder difference from a long round and a short round was around .7 grains less powder to the short rounds.

I've mentioned before, I control neck tension with neck bushings, and I generally ran full cases of powder, never had a setback issue.

Came REALLY close to the hallowed 10x-100 at Perry once in 300 rapid fire... just shot a called high shot, and a called 7 oclock shot to the coach in the string. He just shook his head and said yep, you are right. Both are out about half an inch or less, out of the X ring.... LOL. I"d thought I'd shot em out of the 10 ring. Had a couple of other 9X cleans along the way.

In the end, when the 77 sierra was pushed by enough powder, although it was never as accurate, it was an easier thing to deal with in the end in my mind, plus the short 75 amax scared the heck out my coaches, they just didn't like seeing it...

FWIW this in barrels throated to seat the 90 jlk bullet base just past the donut issue single loaded in the AR so there was considerable jump...

Thank you to everyone for sharing their knowledge and first hand results with this bullet.
I got a LOT of great info from this thread .
Semper Fi
Soup

I ordered 3 of the ASC mags. It will be interesting to see if they help one of my problem children.

Does it make a difference if you get the stainless or aluminum magazines?

I don't know. Mine are stainless; I haven't seen aluminum ASC mags personally (and didn't know they make them, to be honest).