75gr A-Max to mag length?

[svxwilson]

I read in a forum on here a while ago that someone was doing this with decent results loading the 75gr Amax to the max length a magpul mag will accept... . I just got my hands on some and I am researching. I know I can load them one at a time for single shots. Not looking for a barrel burner just something else other than the 77smk I have.
I also just found 2 8lb cans of CFE223 locally! Today was my lucky day.

 

[BobinNC]

I not going to tell you can't do it, but here's what your facing:

Case Length: 1.760"

75 Grain A-Max Nose length: 0.619"

So unless your going to seat with the ogive below the top of the neck, bare your minimum COAL is going to be: 2.379"

And there is no 223/5.56 AR Mag made that let's you seat them out that far....

 

[wareagle700]

I have also read of others doing this. I have never tried it or had a urge to try it but I do have a question. What would be the potential problems with seating the bullet with the ogive inside the neck?

 

[SPEAK338]

The bullet goes up the ramp and pushes into the case causing an over pressure problem as its fired

 

[SPEAK338]

Best bet leave the Amax for the bolt gun and load any HPBT and be happy

 

[LRRPF52]

Yeah, whatever you do, if you have 75gr A-MAX, don't use them. Just send them to me for proper disposal. (I don't own any .223 bolt guns.)

I was in the same camp as the guys above until we had an attendee show up to our DM Course back in March with 200 of them loaded up to mag-length with a crimp. There was no gap at the mouth, and they looked fine, although I immediately thought we would have major issues with that shooter. He was also shooting suppressed with a Surefire can, so I was certain that he would have malfs, blown primers, etc., especially after he said he hasn't really worked with them much, other than doing his pre-course homework by fine-tune zeroing and getting his mv average over a chrono.

He ended up having the best load of anyone in the course, and was making hits as if he had been shooting in the wind most of his life. This was his first course even resembling anything long-range. His friend had made him the loads as well, using 22.8gr of 8208XBR, which pushed them at 2700fps from his 16" Centurion barrel. It was an extremely accurate load, and one of the only .223 loads that would register well on steel from 450yds to 600yds in the extreme wind conditions we had (20mph + full value, 17 degrees F, sideways snow blowing ).



http://i1205.photobucket.com/albums/bb428/GreybullPrecision/Ar-15/1d41f246.jpg

 

[KUSA]

What would be the potential problems with seating the bullet with the ogive inside the neck?

You don't have much neck surface holding the bullet. It would be fine until one got set back while chambering.
People have obviously done it and made it work though as LRRP pointed out.

 

[LRRPF52]

If Hornady made a Hybrid ogive 75gr A-MAX for the AR15, it would kill the 77gr SMK, Scenar, and 75gr BTHP. Increase the length of the boat tail, and it could even have a higher BC like Nosler did with the ABLR.

The current 75gr A-MAX has a G1 BC of .435, which is way ahead of the 77gr stuff, which is in the mid-.3's.

You can also load the 75gr A-MAX in PRI mags to get a little more COL.

 

[Smokerroller]

How about loading some 80 grain SMKs to mag length?

 

[LRRPF52]

How about loading some 80 grain SMKs to mag length?

Seems like it might be worth trying the 80gr SMK and the Nosler CC:



The 80gr SMK has a G1 BC of .420 above 2200fps, whereas the 75gr A-MAX has a .435 BC and will go a little faster win/win. You could also pull the polymer tip of the A-MAX and point them, but that's a little OCD for anything other than hi-power.

The Nosler 80gr CC has a G1 BC of .415, so I think I will stay with the 75gr A-MAX for any of these.

 

[Smokerroller]

Seems like it might be worth trying the 80gr SMK and the Nosler CC:

Great find. Looks like the SMK is a little shorter than the Amax and possibly a little longer on the bearing surface. I already have 500 so I might as well load some up and see what I find.

 

[LRRPF52]

If you have PRI or HK mags, you'll be able to load to a longer COL.

You can also modify polymer mags by creating two channels in the inside of the front wall of the magazine to get more COL, without removing the face altogether like some of the hi-power folks do.

Looks like the 75gr A-MAX's boat tail is as long as it's going to go.

 

[svxwilson]

If you have PRI or HK mags, you'll be able to load to a longer COL.

You can also modify polymer mags by crating to channels in the inside of the front wall of the magazine to get more COL, without removing the face altogether like some of the hi-power folks do.

Looks like the 75gr A-MAX's boat tail is as long as it's going to go.

How much do those mags go for? I have a excessive amount of Magpul 30 rnd mags still in packaging I would happily trade for some of the PRIor HK mags to I've a try with. I just tested the COL with my hornady tool. Bullet ogive rests at the same spot as the hornady match 75gr HPBT. Length including the plastic tip loaded to touch the lands would be 2.369.

 

[svxwilson]

If you have PRI or HK mags, you'll be able to load to a longer COL.

You can also modify polymer mags by crating to channels in the inside of the front wall of the magazine to get more COL, without removing the face altogether like some of the hi-power folks do.

Looks like the 75gr A-MAX's boat tail is as long as it's going to go.

I have a excess of magpul mags I wouldn't mind throwing under the Dremel to cut down the jump the bullet will have and to let me seat the bullet to a longer length. The mag walls are .065" thick. I loaded up a dummy round to find what max length my mags will allow before any mods.

At 2.280" coal the very tip of the bullet would just ever so barely touch the very front body of the mag as it went down. I stacked 10 bullets above it and then emptied the mag by hand and it was tight but no issues.

I adjusted the die just a tad was aiming for 2.275 but got 2.276 and that would load and feed without the bullet rubbing on the front body of the mag.

I re-did my lands measurements just to get a more accurate average and went with a oal of 1.846 which translates to a coal of 2.362. So if I loaded them to max mag length I would have a jump of .087. I do however have .065 of a wall that I can chip away at to lengthen the bullets. If I shaved half the wall away at roughly .030 my jump would decrease to .0507 which is not all that bad.

Every time I pulled the bullet from the lapua brass it had plenty of neck tension on the bullet. I try to swing my bullet pulling hammer consistently so I have a secondary way of testing how tightly my bullets are seated. It took the same amount of swings as all the other typical loads I have for the 5.56 so I don't think bullet tension will be an issue. I will still give the bullet a kiss of a crimp for the added security however and to alleviate any gap that may occur from case to bullet.

Does anyone have any max length measurements on the PRI or HK mags? I found the PRI website and they have metal and plastic mags, do the metal ones have more room?

This will be a fun experiment. I plan to start at the very bottom of Hornadys recommendations and their charts start VERY conservative compared to others like Hodgdon who has max loads 3 gr above what I would touch based off what I have found.... Anyway..... Any other tips or hints???!

 

[svxwilson]

That chart is awesome!

 

[svxwilson]

Great find. Looks like the SMK is a little shorter than the Amax and possibly a little longer on the bearing surface. I already have 500 so I might as well load some up and see what I find.

If you wouldn't mind posting what you find when you load the 80gr pills I would appreciate it. Maybe we can start a thread dedicated to these bullets that "can't" be loaded to mag length.

 

[BobinNC]

I have a excess of magpul mags I wouldn't mind throwing under the Dremel to cut down the jump the bullet will have and to let me seat the bullet to a longer length. The mag walls are .065" thick. I loaded up a dummy round to find what max length my mags will allow before any mods.

At 2.280" coal the very tip of the bullet would just ever so barely touch the very front body of the mag as it went down. I stacked 10 bullets above it and then emptied the mag by hand and it was tight but no issues.

I adjusted the die just a tad was aiming for 2.275 but got 2.276 and that would load and feed without the bullet rubbing on the front body of the mag.

I re-did my lands measurements just to get a more accurate average and went with a oal of 1.846 which translates to a coal of 2.362. So if I loaded them to max mag length I would have a jump of .087. I do however have .065 of a wall that I can chip away at to lengthen the bullets. If I shaved half the wall away at roughly .030 my jump would decrease to .0507 which is not all that bad.

Every time I pulled the bullet from the lapua brass it had plenty of neck tension on the bullet. I try to swing my bullet pulling hammer consistently so I have a secondary way of testing how tightly my bullets are seated. It took the same amount of swings as all the other typical loads I have for the 5.56 so I don't think bullet tension will be an issue. I will still give the bullet a kiss of a crimp for the added security however and to alleviate any gap that may occur from case to bullet.

Does anyone have any max length measurements on the PRI or HK mags? I found the PRI website and they have metal and plastic mags, do the metal ones have more room?

This will be a fun experiment. I plan to start at the very bottom of Hornadys recommendations and their charts start VERY conservative compared to others like Hodgdon who has max loads 3 gr above what I would touch based off what I have found.... Anyway..... Any other tips or hints???!

I have read, but did not personally confirm, that both the PRI and H&K mags are in the ballpark of 2.300" to 2.305" . But that's second or third hand information, YMMV

 

[1slow01z71]

I'd really like to know what the col is from these pri or hk mags from someone that has them. If they really will let you get away with that much more that could help a lot. Hell it would help with the 77s as well.

 

[svxwilson]

I'd really like to know what the col is from these pri or hk mags from someone that has them. If they really will let you get away with that much more that could help a lot. Hell it would help with the 77s as well.

After payday I think I am going to order one. If not this coming payday then the next.

 

[LRRPF52]

PRI's and HK's will allow 2.300" max, but I always capacity-test my longer than book COL's because I learned that the mag can get hung-up as the rounds stack, although that only happened to me with the 7.62 DPMS mags loading 155gr Scenars really long. I still was able to load 15 rounds in a 20 before I had issues, but I took note of this for future reference. I think it's less of a problem with curved mags, if a problem at all, because you usually don't have taper stack with the cartridges.

The 75gr A-MAX is no BS in the wind, let me tell you.

 

[BLDTYLRY]

I have PRI 6.8 mags I use in my Grendel and Max COAL is 2.32"

 

[svxwilson]

I have PRI 6.8 mags I use in my Grendel and Max COAL is 2.32"

Metal or plastic? Does it matter?

 

[BERTMAN77MK2]

My PRI 6.8 mags that I use in the Grendel are metal

 

[BLDTYLRY]

PRI mags are Steel. Unlike the other metal mags, the front of the mag is not made by overlapping sheets of metal and spot welding

 

[svxwilson]

Precision Reflex industries? I thought I saw plastic mags there but upon secondary inspection I was wrong. Thanks guys for clarifying that for me, I should have seen that myself the first time.

 

[1slow01z71]

So whos going to take some concrete measurements?

 

[svxwilson]

Loaded up 10 rounds to magpul max length of 2.275. I did 5 with 22.5gr of CFE223 AND 5 with 23 gr I had a flyer with each but it shot well, no pressure signs. More development to come.

 

[1slow01z71]

What pmag are you using that allows you to load to 2.275? Most I can ever eek out of pmags is 2.25 and still fill them up(20rd). Got any pics how they look in the mag or even out?

I went ahead and ordered one as well in the 15rd flavor. Ive got some berger 80.5s as well to try that would benefit from a little longer COL.

 

[svxwilson]

What pmag are you using that allows you to load to 2.275? Most I can ever eek out of pmags is 2.25 and still fill them up(20rd). Got any pics how they look in the mag or even out?

I went ahead and ordered one as well in the 15rd flavor. Ive got some berger 80.5s as well to try that would benefit from a little longer COL.

I think it is a older pmag. I only did 5 at a time. So I have no idea how they would work with 20. It was tight, I think the nose was touching the mag or just barely kissing it. I loaded them up and then took them out (5 at a time) and didn't see any deformation of the tip. I am going to order a PRI mag just to get the extra .025-.035. I got sub moa out of both the groups today. First group is actually only a 4 shot. Shot the first out of that mag at a gong at 300.


1-4x viper pst scope.

 

[svxwilson]

4 shot

 

[svxwilson]

5 shot group with 23gr CFE223. I am relatively happy with those results. I only had a 1-4x scope, and with the new PRI mags I will get the bullet a lot closer to the lands. I have a feeling this is going to be a good combo. I will have to load some more up and take the chrony with me to verify.
On a side note my SCAR 17shot like shit with the first loads on the lower end of my ladder. I only got through half of the ladder with the SCAR but everything was 1.5-2 moa with CFE223 and 168amax. I found a sub moa node with varget and 168 Amax so I know I can do it. The node with varget was also towards the top of its ladder right when it just starts to compress it 42.6gr.

 

[LRRPF52]

Nice work daddy. Those are at 100yds with a 1-4x Viper PST you say? 1.2 MOA with a carbine and 4x scope ain't too shabby.

What is your velocity with the 23gr of CFE223? I read through the thread, but don't recall what barrel you are using.

The guy who showed up to my DM course had a .223 Wylde chamber IIRC. Interested to see what COL you can get with the PRI mags. Palmetto State has them on Black Friday Sale right now. You could also clear out a channel for the tips in PMAGs with a rat tail file, or one of those wire saws.

Exciting stuff. For those that have 20" guns, you could really kill it with this bullet. Another thing we've been seeing with the Grendel is that A-MAX's behave like Nosler Ballistic Tips. It's basically a hollow point with a polymer tip in the meplat, which exacerbates expansion rapidly.

Nice work.

 

[svxwilson]

Nice work daddy. Those are at 100yds with a 1-4x Viper PST you say? 1.2 MOA with a carbine and 4x scope ain't too shabby.

What is your velocity with the 23gr of CFE223? I read through the thread, but don't recall what barrel you are using.

The guy who showed up to my DM course had a .223 Wylde chamber IIRC. Interested to see what COL you can get with the PRI mags. Palmetto State has them on Black Friday Sale right now. You could also clear out a channel for the tips in PMAGs with a rat tail file, or one of those wire saws.

Exciting stuff. For those that have 20" guns, you could really kill it with this bullet. Another thing we've been seeing with the Grendel is that A-MAX's behave like Nosler Ballistic Tips. It's basically a hollow point with a polymer tip in the meplat, which exacerbates expansion rapidly.

Nice work.

I didn't bring my chronograph with me. It has frustrated me the last few times I have used it. It's a RCBS, been considering getting something different. I will bring it the next time I shoot these. The next go around will be with a coal of 2.3ish instead of 2.275 like this first batch. The 2.275 was just a preliminary test.
The rifle is a stock DDm4v7 with a stock trigger and factory barrel 16" with around 1000 rounds through it (plans for a SSA-E like my Grendel) I didn't know what I was missing out on until I got the SSA-E I have in my Grendel.
And yes I did that with a 1-4x viper pst.
I want to get a Grendel upper for my DD lower eventually.

I looked for the mags on sale and couldn't find them on the Palmetto site. I ordered one from PRI directly and if I am happy with this which I Have a good feeling I will I will order more.

 

[1slow01z71]

Im headed to the range tomorrow and am seriously considering loading up some but Ive only got 100 of them and would hate to waste them on a COL that I cant actually use. According to the hornady book the COL is 2.390 for the 75gr amax so best case scenario you will be .09 short on COL, so obviously case capacity is going to be reduced. My varget 77gr load is 23.8gr and at that point there is a slight crunch but its varget. Ive got some H4895 that I think I wll try. Hornady says 19.3 to 23.3 and 2200fps to 2700fps. I imagine Ill start somewhere around 20gr and go up. FWIW the 75gr BTHP has a book COL of 2.250 so the .140 COL difference is roughly the length of the polymer tip.

So pics and info comparing them to the 80.5 berger fullbore targets



Theyre virtually indentical BC wise with the max at .435 and the berger at .436

My mag should be here end of the week I imagine since I ordered it a couple days ago. I will be testing the loads out in this

20" white oak 7 twist with a giessele national match trigger and swfa 3-15 so I should be able wring out all the accuracy this round has. Just need to figure out where to start and what powder. Anybody know where I can pick up some more 75gr amaxs? 100 ought to be enough for me to dial in the powder charge and get some decent results at 100yds and maybe a trip to the 300yd range but I doubt Ill have enough to make it to the 1000yd range.

Ive also got a magnetospeed so I should be able to get good info for everyone. If you have a box laying around youd like to donate to the cause Ill buy em off of you.

 

[tickled pink]

When I was competing in High Power I shot 69 grain Sierra Match Kings and my Bushmaster DCM would shoot 10 shot groups under 1/2" consistently with my 18 power scope on sand bags. That was at 100 yds. I also shot Sierra 80 grainers at 600 yds. single feed. A lot of guys shot 75 grain match bullets even at 600 yds so they didn't have to single feed. If you can get something a little lighter that is super accurate why do you need to go a little heavier? If you plan on shooting at 1,000 yds. why not go with the 80 grain and single feed?

 

[1slow01z71]

For me personally, single feeding an autoloader is retarded. To each their own and I know the benchrest guys shoot AR platforms single feed all the time. Its just not for me. Plus its fun tinkering. I haven't shot the 80.5 bergers but they were designed to be loaded at mag length. Of course like all bergers they come at a price. I love amaxs as theyre cheap and accurate in everything Ive loaded them in. The 75gr amax has a way better BC than anything else close to it in weight. The 80.5 berger has shown great results fed from a mag but at the cost of being 50% more expensive than the amax. My plan is to have a very accurate load that bucks the wind and performs well to 600. Anything after that will be gravy.

 

[LRRPF52]

Why not the 69gr going fast? Wind deflection. The 69gr is great for trajectory, but the BC isn't competitive with 77gr. A 75gr A-MAX is only 6grs heavier than a 69gr SMK, but it has a BC that is comparable to the 168gr SMK, .435 vs. .447

69gr SMK is .301 - .305 for G1. 77gr SMK is .362

 

[1slow01z71]

Found 2#s of CFE 223 locally and my mag should be here at the end of the week. With any luck I ought to be able to put together some loads to try out Sunday. Havent had any luck finding more amaxs though since hornady has them on their suspended list.

 

[1slow01z71]

Got my PRI 15 round mag in on Friday. Looks like mag length is 2.310 so for sure 2.3 and possibly 2.305 should work well in it. I pick up some CFE this week and will load some up for this weekend if I get a chance. Still no luck finding some my 75s for testing though. Backorder 1K through Brownells but who knows when they'll come in.