.50bmg AMAX Question

[Mordis]

IM reloading for the 50bmg for my father in law, and would like to know the wind drift adjustment for 365yards with a 5mph crosswind. Load 750Grn Amax At 2583fps. I currently do not have ExBall so i only have the free calc at hornady.com.

Thanks for the information, currently 365 yards is the farthest we have to shoot.

 

[Michael Eichele]

Roughly 2.3-2.4 inches in standard air.

 

[Fiftydriver]

Go to:

JBM - Calculations - Trajectory

This is a pretty darn good FREE ballistic program that is on line. Much better then most of the other free programs.

What 50 are you shooting, tell us about your set up. They are kind of a passion of mine. Ballistically kind of dogs but there is just such a huge FUN factor you can never get tired of playing with the big fiddy.

 

[Mordis]

Were shooting a barret 95. Its his gun, but i help with load development. This load has a low velocity spread and hits with 11k worth of muzzle energy. It currently has the standard bipod, no rear mono pod and a shooting bag up front. Scope is Leopold Vx-II with the varmit recticle.

 

[Fiftydriver]

The 95 is a pretty good rifle. Triggers are generally pretty heavy with much more creep then needed and not overly easy to work on that way but they generally shoot pretty well with preferred loads.

One thing I would recommend you watch out for is the VX-II scope. In time it will likely be worked loose by the big 50. Most will tell you these scopes and many other sub $500 scopes will work great on the big 50s. Most that say that will not be shooting their rifles much at all. In fact most that own 50 BMG rifles use them more for conversation pieces then actually putting enough time behind one to get it set up for precision long range shooting.

Anyway, if you plan on shooting alot, keep an eye on that scope. There is a reason that the FCSA only recommend a few different brands of scopes for use on 50 BMG rifles, Leupold MK4s, NF and USO. There are others such as S&B and even the Weaver fixed power target scopes work well.

The problem is the negative g-forces created by the muzzle brake that will work loose a scopes internal workings. Its not the recoil as any scope is made to support the lenses against recoil forces but few have the supports for the forces generated by the muzzle brake.

Hopefully it will serve you well for many, many years but if you see anything odd in adjustment or paralax going goofy or image not being clear and crisp, you know what will be causing it.

 

[Mordis]

Well the scope came with it, it is a used gun. One thing i have noticed, is that when i shoot it, i can feel the wind and blast from the brake. Even tho im behind it?! Its cuasing me to inadvertantly shut my eyes apon firing which is affecting my shots. I can try to force them open but it becomes a chore over a long string of rounds. I was thinking of having him replace the brake with something a little better designed but i dont know if there is any that perform the same or better.(maybe badger ordanances brake??) Untill then is there any advice you guys have for combating my auto blink on firiing? If its happening with the fifty, itll happen with anything good for long range hunting. Tho i must note it does not happen with the non braked 7mmremmag.

As far as scope replacements i plan on checking out the Counter sniper line of scopes, they seem to get good reviews and are decently priced.

 

[Fiftydriver]

Your just dealing with something that everyone has to deal with when shooting a 50 BMG or any large conventional chambering when using a muzzle brake.

Its not the recoil that is making you flinch, its the muzzle blast which you can actually feel on the shooters face. When I started shooting the 50s, I was comfortable shooting with my mouth slightly open. Just happened when I relaxed and concentrated on shooting. Never had any issues shooting smaller chambered rifles, in fact did not even realize I was doing it but when I would touch off a 50, I could feel the muzzle blast in my teeth, literally and I did not like it.

You can also "FEEL" the blast on your forhead, cheeks and chin, MUCH more then anything else out there, just part of shooting the big rifles.

One thing I have found that helps is to make sure you wear a good set of shooting glasses which will block alot of the area around your eyes from the blast. The eyes are very sensitive to muzzle blast so the best way to do this is to block that blast with glasses.

Also, If its a recoil issue, I would recommend you order in some lighter weight bullets for practice. Something like the M33 ball in 647 gr FMJ will REALLY cut down recoil. I am shooting these in my AR-50 for a plinker load and if you sort bullets, they are suprisingly accurate, its nothing to get 1 to 1.5 moa accuracy with new M33 bullets if they have been sorted at ranges out to 1500 yards or so. Recoil is dramatically dropped and it will help you "TRAIN" your brain to what the 50s present when fired, its a totally different game.

As far as more effective muzzle brakes, there really are not many better then the Barrett brakes other then the Armalite AR-50 brake but the AR brake will increase muzzle blast to some degree.

That said, the AR brake has blast sheilds that protect the shooter to some degree, at least opens up the protective cone from the muzzle blast a bit better then the Barrett. If you look at the AR-50s muzzle brake you can clearly see the blast sheild, I can not imagine it would cost much to have something like this made for the Barrett rifle and just sandwich it between the brake and barrel to help protect the shooter from blast.

But as far as reducing recoil, you have about as good a brake as there is out there for the 50 BMG.

Again, if recoil is causing the blink, practice more with the 647 gr bullets to train your brain, and eyes and also cut your string length down. Your body it telling you something if your starting to blink. If your blinking, your likely flinching. That is if your blinking before the trigger breaks, if your blinking after the trigger breaks, your worrying about nothing. I do not know anyone that can shoot a 50 BMG and not blink after the trigger breaks.......

You may be worrying about nothing.

 

[Mordis]

My blinking is happening after the trigger break, essentialy during the blast sequence. SO far i cant get it to group under 3" at 365yards... Tho i wounder if that is good or not.

 

[Fiftydriver]

If your getting 1/3 moa at that range you are doing better then the Barretts will generally do. THat is very good for a Barrett rifle with factory barrel. I would say your trying to improve on something that is way better then average performance to begin with.

Do not get caught up in "The grass is always greener" theory. About the best I have seen with the Barrett for consistant accuracy at long range is around 3/4 moa. That is not saying you will not get tighter groups from this from time to time, this is an average group size I am referring to.

I would say your there, get out and shoot at longer ranges. Again, if your blinking after the trigger breaks, do not worry about it. Follow through properly and you will never have a problem. I have said it before and will again, I would bet there are very few if any out there that can trip the trigger on any 50 cal and not blink after the trigger breaks.

Good loading and shooting, your getting accuracy out of the Barrett that is not typical for that rifle.

 

[Mordis]

Fiftydriver, that 1" was a typo, i didnt catch it till i hit post, so i went back and edited it. Im getting consistant 3" groups at 365 yards each time. Tho i have seen them go as low as sub 2" on occasion. My appologies at the typo.

Fifty you seem to be a very helpful person, and a custom smith to boot. Do you mind if i PM you some questions i have regarding caliber selection??

 

[Fiftydriver]

You are still better then 1 moa which for a factory rifle is pretty **** good. Yes, with certain loading techniques you could likely get consistant 3/4 moa or perhaps even play with that 1/2 moa level but in all likelihood, your about there.

I would bet you would have to start sorting by weight your cases, primers and bullets, measuring baring surface and sorting by that as well. Turning your case necks and really tightening up your neck and bullet run outs to see a measurable improvement in what your getting right now.

I used to do all that stuff but have since stopped simply because you had roughly 20 minutes into each case before you even threw a powder charge and it just got old to me. Now if your match shooting, needs to be done. If your happy with hitting what your shooting at in the vitals, I would say its up to you but likely not going to make a huge difference in group size with a factory barrel, chamber and throat.

Also remember that you should test your loads at longer ranges, at least 800 yards and preferrably 1000 yards or more. A conventional long range rifle using vld type bullets will "go to sleep" around 100-125 yards. This means the bullet will shed the effects that the rifling in the bore impose on the bullet and the bullet will spin true around its own center of gravity.

This also happens with the 50 BMG but because of the great weight and length of the bullets, it generally happens around 200-250 yards. What this means is that often times you will see groups at 100 and 200 yards look very similiar but groups at 300 and 800 yards will also very close in size. Often times, the longer range groups will be smaller in moa measurement, many times dramatically smaller.

Stretch her out and you will learn much more about the quality of your load.

As far as PMing me, no problem but I would prefer you e-mail me as you will get a quicker response that way. I reply to PMs when I get caught up with e-mails and they always take a back seat to the e-mails so shoot me an e-mail at the address in my signature below and I will offer any experience I may have that can help.