Serbu BFG-50A 50 BMG


Official LRH Sponsor
Jun 12, 2004
Fort Shaw, Montana
Hey guys,

Just wanted to post some pics of a new toy I got the other day. This has been about a year in the works. Many of you know I have been in the 50 BMG crowd for a long time and have owned MANY single shot 50 BMG rifles and built many more precision single shot rifles in my 510 Allen Magnum wildcat based on the Armalite AR-50 platform.

Still, I have always wanted a high quality, semi-auto 50 BMG rifle. For many years the Barrett M82A1 was about the only game in town. This is a great rifle for what it is, utterly reliable in all conditions but while some claim it to be a long range precision rifle, it hardly fits that bill. Most of the time, about the best accuracy you will get at 1K will be around 2 moa and usually its not that good unless your using the best ammo possible.

This is because of the barrels recoil operated system and its floating barrel design, its barrel is always moving back and forth and getting long range precision from that is hard to do. Again, for what its designed to do, it works great and in all conditions.

Being an accuracy minded firearm manufacturer, I just had a very hard time spending +$10,000 on a 2 moa rifle when I could always build myself a full blown APS AR-50 in 510 AM and get 1/2 moa for half that cost.

Well, a few years ago, I contacted Mark Serbu who was advertising his new BFG-50A rifle which was a fixed barrel, semi-auto 50 BMG rifle claiming that it would blow the doors off the Barrett in accuracy. At that time, my research showed that production was non existant and this was more a prototype rifle design.

I kept track of the rifles development with the normal issues that come with a new rifle design of this type and around the later part of 2012, I called Mark up and placed an order for one of his BFG-50A rifles.

Well, it arrived last week. I have been able to take it out twice to the range when testing customer rifles and put a few rounds through the little beast. Here are some pics.




The rifle is not perfect and in researching the BFG-50A rifle, the main complaints are misfires caused by an off centered firing pin in the bolt and the rifle short stroking and not picking up and chambering the next round when firing.

Mark had assured me the off center firing pin issue had been resolved and it was simply a bad batch of bolts. He said the short stroking of the action was simply due to guys shooting cheap, poor quality surplus ammo in their rifles and that high quality match ammo would function perfectly well. He did not recommend handloads as all of these manufacturers will not recommend just because of the nature of being sued today. For me however, there would never be a factory loaded round go through this rifle and he knew that.

So, Just to get things started I took 100 rounds of virgin Win 08 50 BMG brass, threw in 225 gr WC872 surplus powder with a CCI-35 primer and topped everything off with a reasonably priced 650 gr Win M33 ball projo. Chrono'ed velocity was just a hair under 2850 fps out of the 26" barrel length. Thought that was **** respectable for this barrel length

The rifle has a very nice short throat length as its designed for use with ball ammo. The neck is also very quality only 4 thou over loaded neck diameter. Now, by our precision standards, this is pretty loose, but by most 50 BMG factory rifle standards, this could be considered MATCH!!!! Chamber is also min spec. I had to FL size the virgin Win 08 brass of some of them were a bit tight chambering. Very impressed with this.

The first range session was a learning experience. I had fired many Barrett M82A1 rifles and was impressed with their recoil levels as being very comfortable. Different then the AR-50 with its amazing muzzle brake but very comfortable none the less. The Serbu BFG-50A on the other hand has the least amount of recoil I have felt in any portable 50 BMG class weapon system. MUCH more comfortable then the Barrett even though its 10 lbs lighter in weight. The lower rifle weight simply allows the muzzle brake to be more effective at controlling felt recoil. It is a VERY comfortable rifle, recoil is on part with one of my lightweight XHS rifles chambered in 375 Allen Magnum.

The action works very slowly as well. The big cases are lazily lobbed out the right side of the rifle. In fact they come out so slow, for the first several shots fired, I thought, there is NO WAY that that bolt traveled back far enough to pick up another round but I was wrong MOST OF THE TIME.

On the first outing I did have two short stroke failures to feed. The problem however I found out was my shooting position more then anything else. I was sitting on my shooting bench seat and these rifles are long enough that they do not allow you to "LEAN" into the rifle off the bench seat, as such, the rifle was basically free recoiling. Now even though these rifles are gas operated, they need some resistance on the stock to function properly.

After these two short stroke failures, I set up the rifle on the ground so I could get behind the rifle for a solid shoulder support and never had another failure to feed.

Again, the rifle as it comes from Serbu is not perfect. There are things that will be changed and already have parts on order to correct.

1. LOP Is only 13.0". VERY short for a 50 BMG class weapon system. I am 6'3" and will be adding 1" to the LOP. This is not overly difficult for me to do as a firearm manufacturer but would be more difficult for a general customer.

2. The scope rail base, while very long(GOOD DESIGN) is very low for the receiver design. As such, it will need higher then normal rings for proper eye position to the scope. In the pics, I have two sets of 1.000" high NF Ultralight Tactical rings on the 5.5-22x 50mm NXS NF scope and while its shootabe, the scope is around 3/8" to low for really comfortable shooting. I have two sets of extra high NF tactical steel rings already headed my way to correct this. I do not like mounting a scope high on a 50 BMG class weapon as its very hard on the scope, that is why I am going with my standard 4 ring set up to control recoil energy(2 rings), Negative G forces generated by the muzzle brake(2 rings) and also just give the scope body more support with the 4 rings.

3. The bipod SUCKS!!! Now, it is what it is and its designed for to be a simple, rugged bipod for field use and for that purpose, it works just fine. Still, its very tall and has no control of the cant system. It just rocks back and forth very easily with no resistance. A new bipiod is already on order that will greatly solve this problem!!!

Those are the bad aspects of the rifle that I have found so far. There is a lot more good to be had.

1. Very light rifle design at 23 lbs and very well balanced.

2. VERY comfortable from recoil stand point and muzzle brake is not all that bad as far as muzzle blast is concerned. The AR-50 muzzle brake feels like someone is slapping you in the forhead, this rifle is nothing like that which kind of surprised me with the relatively short barrel length. Very impressed.

3. Trigger is very, VERY good for a production 50 BMG. I have never shot a Barrett M82A1 that did not have a creepy trigger. The trigger on this rifle is right at 3 lbs and breaks like glass, extremely impressed with this.

4. Very simple design. Rifle breaks down in about 2 minutes and you only need the point of a 50 BMG bullet to do complete disassembly.

5. Very high quality starlight hard gun case included in package.

6. Very impressed with its accuracy so far.

I set the rifle up at 500 yards to get scope dialed in as this range was a more protected shooting range in case the first shots went somewhere I was not expecting them to, BAD THING with a 50 BMG. That did not happen though and rifle shot very well at 500 yards just making a big crater in the dirt after reducing the 2 moa sized target rock to pretty much dust. Then moved out to 1000 yards and the rifle easily held 1.5 moa. I was impressed with this, especially since I was shooting mil spec M33 ball projos.

On the second outing, I shot some of the Lehigh 650 solid Ball match bullets. Had to drop my load to 220 grains of WC860 on this load and velocity was right at 2800 fps but accuracy improved noticeably and was consistently shooting 1 moa class groups with some a bit less but honestly, the rifle was shooting around 1 moa at 1000 yards. For a semi-auto 50 BMG, this is GREAT accuracy. I have never seen a Barrett M82A1 shoot to this level of consistency.

I also have some Barnes 647 gr TSX that I want to try. I am sure these will allow a bit more speed then the Lehigh solids and will be a better terminal performing bullet if I ever decide to use the rifle in the field which at 23 lbs is certainly possible. This is the only 50 BMG rifle I have owned that I could shoot off hand. Not easy but its certainly possible.

So from my early testing, the rifle is much lighter then the Barret, noticeably more accurate, more comfortable to shoot and several thousand $$ cheaper in price.

So far could not be happier. Now if only someone would make a semi-auto 50 BMG with a mag length long enough to use the 750 gr A-Max bullet, we would really have it made!!! Course, that's what the precision single shots are for!!!
Good write-up Kirby! 1MOA is really good accuracy out of a recoil machine like a .50 BMG.

Post up some vids on YouTube if you get a chance. I'm curious to see it in action.
with your back ground, why dont you just build one Kirby?

Building a semi-auto 50 BMG using manual metal working machines would be a feat for sure. Do not have the stamping machines needed to make press formed receivers either.

Single shot precision rifles, no problem at all, build lots of them, its the semi-auto aspect that I would have no desire to try to tackle with my equipment!!!
Good write-up Kirby! 1MOA is really good accuracy out of a recoil machine like a .50 BMG.

Post up some vids on YouTube if you get a chance. I'm curious to see it in action.

I will get some video when I get it finished up how I want it after getting the scope a bit higher, lengthing the LOP by an inch and getting the bipod replaced. Also going to design a mono-pod mount for the rear end .

1 moa is very good if your using ball projos, can not complain about that. 1 moa with custom match bullets in a precision single shot 50 BMG class rifle is nothing to be to impressed about. In a semi-auto rifle however, it shows GREAT promise.

Again, when I get her set up how I want it I will get some video taken.
GREAT WRITE-UP!!! I too am interested in what the video will look like. One thing that I didn't see was the actually price for the unit. I read where you said it was a couple thousand cheaper than the Barrett, but I didn't see an actual price tag. Thanks again!
Serbu charges $6700+ shipping. That includes complete rifle with one ten round Barrett magazine and a $300 starlight hard case. Many used Barrett M82A1s are $2500 to $3000 more then this if they are in good condition. New Barrets are at least $3000 over this price.
I love my Serbu BFG-50A! I too had some short stroking and miss fire issues and all got fixed very fast by Mark. When I got it back I unloaded a full clip of API's and that was just bad ***!!! Great write up!
I love my Serbu BFG-50A! I too had some short stroking and miss fire issues and all got fixed very fast by Mark. When I got it back I unloaded a full clip of API's and that was just bad ***!!! Great write up!

I believe about 90% of the short stroking issues are a result of low pressure ammo in current rifles. It seems that early versions of this rifle had relatively rough chambers which were causing some issues with extraction, short stroking and broken extractors. My BFG-50A however seems to have a very smooth chamber. Time will tell.

One also needs to realize that when you handload for a 50 BMG, you want to load it to the 50 to 55,000 psi range and no more. Loading it to the point where the pressure will permanently deform case brass will also result in a lot of problems. These huge cases have ALOT of baring surface to the chamber, if you load them to high in pressure, that's ALOT of grip that has to be overcome to clear a fired case.

Point being, the 50 BMG is a relatively low pressure chambering, load it to its designed pressure ranges and most function problems tend to go away.

Just got my APA bipod in and will be moding the Serbu to mount that bipod as high as possible to keep COG low. I also got the leg extension kit and extended cant locking lever, should be a good fit, just have to get the rifle converted to allow it to mount the bipod.

Glad to hear your happy with your Serbu, how long have you had it and how many rounds do you have through it. I would agree, running 10 rounds through a 50 BMG is certainly an event to witness as a shooter and witness!!!
My chamber also seems to be pretty smooth. One thing also was that the gas port on the gas tube to the gas block was a little small. My buddy opened it up a bit and the short stroke went away but still had the miss fire issue. Thats when I sent it in and they completely took care of the issue. I've only got about 60-70 rounds through it at this point. I'll be looking to reload with the API projectiles pretty soon. Let us know how the bipod work out for you.
Was your misfire issues a result of an out of center firing pin? From what I hear, that was a main issue with earlier rifles and with a 50 BMG, the firing pin needs to be pretty well dead center for proper primer ignition. A bit loose headspace can also be a serious problem with misfires.

The 50 BMG primers need a serious amount of impact energy to ignite them.

From everything I have heard, Serbu has taken very good care of his customers with these problems, another reason I decided to invest in one of Marks rifles.

I am really surprised that Mark has not designed an adjustable gas port system similar to most of the piston driven AR-15 rifles. That would really help with the small gas port problems. With the wide variety of 50 BMG ammo out there, having the ability to adjust your gas port diameter would be a huge benefit. Three settings would be plenty, one with a large port for low pressure surplus ammo, a smaller port for higher pressure match ammo and a shut off position so that someone could shoot the rifle as a single shot if they wanted to suppress their rifle.

Course all that would add cost to the rifle and I believe Marks goal was to get a great rifle out at a more reasonable price then the Barretts and I believe he has done that very well.
Yes I was getting off center primer hits and they replaced the bolt, bolt carrier, recoil spring and trigger hammer spring. Works like a champ now using Lake City API rounds. I agree the adjustable gas port would be a good idea but like you said, he want's to keep cost down for his customers. I'm really happy with my purchase. I've shot it at 1200 yards at a 16" steel plate, was a little low first shot adjusted the scope and hit it on the second shot. This thing is pretty acurate, I want to see what it will do at 1 mile.
And that's with ball ammunition, load up some match quality ammo, even if using match ball projos like the Lehigh and it should do even better.

Maybe I need to look into designing an adjustable gas port that's an aftermarket option for this rifle.
GREAT writeup! Thank you for taking the time to post your experience with the SERBU. Your proposed mods would be interesting indeed.

I am disappointed to learn that a semi-auto cannot be used with the 750g AMAX. That would be my bullet of choice in a .50. Can the SERBU 50A be fed single shot, if desired? I am given to wonder if there is such a thing as a single shot follower for the Barrett Mags.
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