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Posted: 11/7/2025 2:53:02 AM EDT
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I keep hearing that any barrel length shorter than 11.5" will prematurely wear out the gun due to the gun beating itself. If this is true, should a 10.5" use the heaviest bullets available, or does bullet weight not matter? |
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I shoot 55gr Federal or Winchester in all my guns at a rate of around 10k a year without issue Barrel life varies between manufacturers but a barrel swap is neither complicated or expensive when the accuracy starts to degrade. Heavier bullets are definitely recommended for defensive purposes in shorter guns. 10.5, 11.5 and 12.5 guns use either Speer 75gr Gold Dot or Black Hills 77gr OTM for anything but paper or steel. |
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I keep hearing that any barrel length shorter than 11.5" will prematurely wear out the gun due to the gun beating itself. Maybe in 1975 when there was no aftermarket. Just throw in an H2 or H3 buffer and call it a day. You can further soften the action by getting a suppressor and adjustable gas block or BCG. Heavier bullets like 77gr will help your short barrel with consistently hitting long-distance shots (300+) over standard 55gr though. |
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The super shorties are a compromise on a system designed around a 20" barrel. They are harder on parts as a result. I love the shorties but they have their limits. They are really a 300m and under gun, more realistically 200 and under. Mine was still working after 11-13k rounds and shot fine BUT the accuracy degraded a bit. I now have 2 shorties, 9 14.5-16" rifles, and a few more 20s. |
| Short barrels and heavy bullets are often referenced together because lighter bullets can't reach the velocities needed in a short barrel to tumble and fragment. Longer heavier bullets tumble and fragment at lower velocities, which are achievable with a shorter barrel like an 11.5. |
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Harder on parts? Yes, it is. Beating itself to death? No, not if you use reasonable parts (not a wallowed out gas port). Use good parts and makes use the gas/recoil system is properly balanced and it's a non-issue for almost everyone since the vast majority of people will never shoot enough to break stuff. Are heavy bullets better? Well, better for what? Generally, yes, heavier projectiles are preferred, you're going to gain energy at the expense of velocity. It depends what you are shooting. You'd likely lean towards lighter bullets for smaller critters at shorter ranges. FWIW, I am partial to both 55gr and 77gr for different uses. Both kill things very well, but if it is either coming out of a short barrel or being shot at long ranges then 77gr it is. The ballistic benefits of heavy projectiles and modern projectile design mean that it makes a huge difference in some cases and virtually none in others. Ex: I deer hunt with a 10.5" pistol and 77gr heavies I definitely wouldn't select my 55gr soft point rounds for that. I also predator hunt where some of the shots are long and also use heavies there. For closer stuff, training, varmints, or shooting a lot - 55gr is the obvious choice due to cost, ease of replacement, and, primarily, because the ballistics benefits of longer range and higher retained energy are wasted. JMO, worth what ya paid for it. |
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You have two different things under discussion: -Bullet weight: SBRs will run fine with 55gr, but ballistic and terminal performance is better with heavier bullets at the lower velocities generated by SBRs. So it depends what your goals are. For blasting or high volume close range training, 55gr all day. For any "serious use", I would be favoring 77gr. -The gun "beating itself to death": Not really dependent on bullet weight. Yes, especially all the 10.5's I've had are some degree of overgassed, some brutally, and show parts wear faster than longer barrels. You are going to have to replace consumables like bolts, cam pins, gas rings, etc more often. How much more will likely be dependent on the gassing of your individual barrel. That is, until Geissele phased array turns this paradigm on its head.  |
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Ran a MK18 for a long time. Yes, you will generally have a shorter lifespan on parts than it's 20" or 14.5" counterpart, especially when suppressed. But the whole "beat itself to death" thing is exaggerated a lot online. And you have lots of options now with buffer weights, choice of gas port size, etc. That said, it's good to pay closer attention to wear items when you clean your gun. As far as ammo selection, it's come a long way. We are running a 75gr SBR optimized ammo now that utilizes a powder to burn more efficiently in a short barrel and a projectile matched to the estimated velocity. There are tons of flavors to choose from nowadays. Select a round that performs the way you need it to at the velocity that you're getting from your rifle. |
| How has no one even addressed the fundamental problem with the OP's post? Bullet weight has nothing to do with the function of the gun. You need to go back and watch a video on how the AR-15 gas system functions. Unless you are shooting a blow back PCC, bullet weight does NOT MATTER in relation to the function of gun, only ballistic performance. You need to look at ammo pressure, gas port size and location, buffer weight to affect the function of an SBR. |
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Not necessarily "heavier bullets" but generally speaking the heavier ones tend to be Open Tip Match - or OTM - that doesn't rely on velocity for lethality. However there might be 55gr or less that are considered "defensive rounds" but they tend to be very pricey and rarely produced. The problem with shorter barrels is that velocity is needed for the FMJ type rounds to pitch and yaw when it hits a target. It seems like the velocity needs to be about 2800~3200 fps for a round like a m193 type or m855 which can be easily done out of a 14.5 or above. If all you're doing is going to a range or shooting at classes, these things probably won't matter as much. As far as wearing, you can minimize it with controlling the gas coming back but then again I wouldn't really stress it. Keep in mind you should consider the entire upper assembly - barrel, bcg, buffer, and spring to be wear parts that need to be changed especially for a high use item. The only way to not wear it is to not use it at all but anytime you go out, you're going to wear it down. You can probably minimize it a little by using adjustable gas blocks, bcgs, or heavier buffers or springs but even then you're only increasing the life span marginally. In other words, you're probably spending money better if you're actually using it instead of worrying about how long it'll last. There's no way to make a gun run indefinitely, and whatever reduction you use will only prolong its life in non-measurable amount that highly depends more so on heat than just reduction in wear. |
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Quoted: I shoot 55gr Federal or Winchester in all my guns at a rate of around 10k a year without issue Barrel life varies between manufacturers but a barrel swap is neither complicated or expensive when the accuracy starts to degrade. Heavier bullets are definitely recommended for defensive purposes in shorter guns. 10.5, 11.5 and 12.5 guns use either Speer 75gr Gold Dot or Black Hills 77gr OTM for anything but paper or steel. I use mk318 mod1 in my 10.3 and my 16 inch. M855 is good enough to get on paper when sighting in, then just accept the POI shift when training. |
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Higher bullet weights don't cause parts to wear faster in ARs. The best bullet for ballistics, both internal and external, depends on what you're shooting and how far away it is. As a gross over-simplification, 55 grain and lighter bullets won't deliver the best terminal ballistics in an SBR. To evaluate the terminal ballistics of a bullet, you need to know what it's designed to do at particular velocities. Or, you can get some 5.56 NATO pressure polymer tipped 77 grainers, and call it good enough. |
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I suspect with the growing use of FRT's we are going to learn quickly what AR's of various barrel lengths/ gas systems lengths/buffer weights wear out/fail fast & what holds up better than others. Op, Yes, heavy bullets do perform better when using shorter barrels & bullet weight has almost no effect on parts wear. |
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