Do I Need An Extra Bolt Carrier?

As far as spare BCGs, they're good to have around but tend to morph into a new AR!
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I have also noticed this phenomenon it seems any spare AR parts I have laying around grow into new rifles;)
 
Since I already fired off some newbie questions...maybe one more.

My barrel has a 1:7 twist. How does that make it functionally different from, say, 1:9 or 1:14?
 
The faster twist is better for longer (which are usually heavier) bullets. So you're 1:7 should be good for just about anything you want to shoot, say 55 to 77 grain bullets. A 1:9 may not be as good with the heavier loads which tend to be more effective. Although many people have had good luck shooting heavy loads with 1:9 barrels.
 
Will that make it any worse at stabilizing lighter bullets?

The ammo I have for it now is PMC Bronze 55gr. It was 9.90 per box of 20(!)
 
It's not about the weight of the bullet as much as it is about the length of the bullet in contact with the rifling. Heavier bullets are generally longer (apart from tungsten ones which are rare) and require a faster twist to stabilize at different velocities. A 1:7" twist barrel works perfectly fine with the vast majority of 50 gr + ammunition. It's the standard barrel twist for our military who use M193 projectiles which are a 55 gr FMJBT.
 
Will that make it any worse at stabilizing lighter bullets?
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Depends on the bullet and what you're trying to do with it. I tried shooting some Barnes Varmint Grenades through my 1:9 AR and they were literally coming apart out the end of the barrel because the twist was too fast. 1:9 is optimal for the 55 grainers and 62 SS109's, but also handles plenty of other weights pretty well. In all but the heaviest or lightest of bullets you should be pleased.:cool:
 
M193?

>>It's the standard barrel twist for our military who use M193 projectiles which are a 55 gr FMJBT.

I thought the US military stepped away from M193 back in the late '80s time frame in favor of the 62gr M855? The new bullets tumbled when shot from the old M16A1s that a lot of NG units were still issued and it caused quite a lot of media coverage at the time.
 
It's never bad to have an extra but it's not always necessary. I would buy ammo instead and shoot it til it breaks (doubt it will happen any time in the next couple years unless you are REALLY abusing it) and buy replacement parts as needed.
 
extra parts...

>> Be careful buying spare parts, they turn into complete rifles.

It happens and generally it's easy to justify.

(Personal, Deep thoughts) "Wow! I really like this new VTLOR stock. Geez, it seems like a waste to let the old one just sit on a shelf, maybe I should sell it on eBay.

Hmmmm... I have that extra bolt carrier too, oh... and that mil spec trigger that I replaced 6 months ago with a Timmney.

Wow, I'm 17/54ths of the way to another AR! All I need is a lower, upper, and a LPK.

OMG, snap out of it moron... the pseudo-spousal unit will drop a bowling ball on you in your sleep if you buy another rifle.

But then again, she always complains that I have too much "gun stuff" sitting around and that I have to many unfinished projects. Wow... I really need to be more considerate of her needs. I need to do this for HER! Lets get this thing assembled and stored safely out of her way in the gun safe."
 
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Law Scholar said:
Will that make it any worse at stabilizing lighter bullets?
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My personal experience has been that a 1:7 will shoot 45gr JHP WWB as accurately as a 1:9 will. That is the lightest I have gone.

The two major issues I see discussed concerning lighter bullets in a 1:7 twist are:

1. In very fast, thin-jacketed bullets, the 1:7 twist can actually spin bullets apart; but we are talking extremely lightweight bullets designed for varminting small animals like prairie dogs.

2. The faster twist can make low-budget blasting ammo even less-accurate by accentuating wobble due to defects in the jacket or bullet.

In tests the military has done, there was zero difference at 300m between 55gr M193 through a 1:12 barrel and 55gr M193 through a 1:7 barrel. The group size was almost identical. I believe kraigwy has posted that article a few times if you want to search for it.
 
Wow. I think this is my first post in about 8 years...I guessed my old password.
I was in college then!

Anyway. This thread may be as old as I am...but I wanted to pass this one on.

broke.jpg


First round of a MagPul Dynamics class. This is a DPMS bolt carrier on my old patrol rifle. She had over 5,000 rounds through her when this happened.

I swapped it out for my backup personally owned Bravo Company rifle...zero problems the rest of the time I used this rifle...there were some user issues :D but those were caused by me trying to do my best.
 
i keep an complete extra bolt and carrier. Mostly because i have 5 ars and shoot them alot and figure someday somethings going to break. But up till this point its sat in the parts box. Only thing ive ever had break was the gas block on one and that was my own fault. I dropped it on the cement floor when i was cleaning it.
 
I have wondered about this big time for about a year. I have a basically brand new Bushmaster AR srt ip as a CQB carbine. It's a present for myself for surviving major back surgery last Oct and I finished it's customization last December. Had the gunsmith finish some stuff and then also go over the rifle making sure it was all good and ready to rock s d roll and once-overed. He said it was great n

The thing is ppl recommended the new BCG. I would like to get a new one ( and better one ) but there are $99 johs all the way to $500 - I want a real good one but not a $500 one. And then I'll have a Brand New Bushmaster BCG for backup. So what should I get ?
Also I want a heav buffer bit do I need any info?

Some ppl say Bushmasters are " Overgasses" so won't a Heavu Buffer help ? Also can I get as heavy as I want or is there' a method ? I see Heavy , H1, H2 , H3 , tungsten z, super duper carbide diamond heavy etc.

Can I Just buy the super heavy one and be done )?

Tytyty.
 
my beowolf is on a .223 lower and the buffer has worked just fine for that so i have to doubt the need for anything heavier then what came in it.
 
The thing is ppl recommended the new BCG. I would like to get a new one ( and better one ) but there are $99 johs all the way to $500 - I want a real good one but not a $500 one.
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The key features from the military standard are:

1. Properly staked gas key wth correct fasteners.
2. Shrouded firing pin
3. Upgraded extractor spring
4. MPI/proofed bolt made out of Carpenter 158

Daniel Defense, Bravo Company, Colt are 3 companies that meet that off the top of my head. I am sure there are a dozen more out there. Those are the important aspects and a BCG with those features will last a very long time, though the bolt will probably need replacement around the 10k mark, depending on the firing schedule. You can get super-steels and ceramic no-lube coatings; but you start to hit the point of minimal gain for money invested.

Can I Just buy the super heavy one and be done )?
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The first thing I would determine is whether your Bushmaster is actually overgassed. If it is isn't, then I wouldn't worry about it now. The easiest way to tell this is to look at ejection. If it is ejecting empties forward of 3 o'clock, then it is probably overgassed for that ammo/buffer/spring combination.

A super heavy buffer can cause function problems just as well as a too light buffer. If you don't know what you are doing, I'd stick to an H-buffer or standard carbine buffer.

Another thing to keep in mind is that the gas port can erode with use, so a rifle may be just fine with a carbine buffer now; but 15,000 rounds later it is overgassed with the same buffer.
 
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