Quick question, Para…I have one of these rifles as well, purchased in California, in 94 or 95, it’s a tack driver. If I replace the standard bolt carrier with the LMT semi auto BC, do I need to headspace it?

In my opinion, you never have to headspace an AR.

quote:

Originally posted by parabellum:
In my opinion, you never have to headspace an AR.

this,

as long as you are confident in the parts you bought,

they were built to be able to swap parts as needed, including bolt and bolt carrriers, with out worry,


IIRC the Gov't ran a field guage thru the M16's once a year or before they were deployed anywhere,

of course that was what my Dad did for the Reserves and he retired in 97, so not sure if that is the case now,

Kyjondeere sent me a pic. Here's the LMT semi-auto carrier and the Colt ban-era carrier side by side. You can see how much of the firing pin shroud Colt removed. That's an obscenity.

Don't forget to lube the four carrier rails, the cam pin track and the bolt lugs, and keep lube off of the the firing pin and out of the firing pin hole in the carrier. This also include the hole in the cam pin, where the firing in passes through- not a single drop of lube, but of course you can rub a bit of lube on the outside of the cam pin.

I wound up with one of those carriers in a trade last year. I got rid of it as fast as I could.

OLD THREAD WARNING++++++


As I posted on the first page, I have a post ban Colt HBAR Match just like this one



I guess I never opened it up because I swore it had that stupid trigger block thing. Anyway, I grabbed it the other night to show it to a bud and it does not have the trigger block (yayy me) but it does have that shaved bolt carrier. It also has the weep hole for a proper breakdown pin, currently has the threaded one. I am not sure about the trigger pins being oversized or not


The link Para posted to that Lewis Machine bolt carrier is no good and they are not showing one available. I searched on some other sites and found BCM, Wilson combat and others but how do I know if it's a semi auto bolt? Only a few listed them as auto but no semi.

It is marked .223, so no 5.56?



I found a video of a guy that removed the trigger block

I have an HBar and should examine it.

quote:

Originally posted by Para:
I seem to recall that if the lower is drilled for the detent (and yours is), you can use a standard push pin.
I hate the screw setup. So stupid.

Quick question, what does the “weep hole” do?
My Colt competition H-BAR has the standard size pin holes but no weep hole? Can I install a regular pin and detent?
It’s a post ban AR so no evil features like a flash hider or bayonet lug.

Do the HBAR's with their restrictive modifications have history of malfunctions?

quote:

Originally posted by KMitch200:

Quick question, what does the “weep hole” do?
My Colt competition H-BAR has the standard size pin holes but no weep hole? Can I install a regular pin and detent?

The weep hole is so you can put a drop of oil into the spring for the forward pivot pin detent spring.

And IIRC, you can replace the screw captured pivot pin with a regular captured pivot pin and detent by adding the spring, detent and pin.

Warning
That detent will self launch into the stratosphere, so watch a few videos about installing it, or put a large ziplock over the work area to help find it when it’s time for launch. I’ve only done it 2 times where I didn’t launch the detent-so good luck, don’t die.

quote:

The weep hole is so you can put a drop of oil into the spring for the forward pivot pin detent spring.

And it means that it has been machined to accept a traditional pivot pin with detent and spring


I did order a Wilson Combat semi auto complete bolt carrier from Buds. After ordering I realized I could have also gotten a full auto one because mine doesn't have the trigger block, Derrr

quote:

Originally posted by MikeinNC:
Warning
That detent will self launch into the stratosphere, so watch a few videos about installing it, or put a large ziplock over the work area to help find it when it’s time for launch. I’ve only done it 2 times where I didn’t launch the detent-so good luck, don’t die.

Ahh, just like the 226 mag catch stop! I only waited a week for the replacement to arrive.

Is there a history of Colt HBAR's jamming because of the hinge pins, bolt carriers and/or sear blocks?

quote:

Originally posted by RichardC:
Is there a history of Colt HBAR's jamming because of the hinge pins, bolt carriers and/or sear blocks?

I have a post ban Colt AR excuse me, Match Target Competion HBAR.
It has NEVER malfunctioned.

You can’t use a M16 profile BCG because of the sear block and since Geissele makes a great trigger for the dumb oversized pins that function with sear block in place, that’s what it has in it. The screw hinge pin is dumb but it doesn’t cause malfunctions, just a PITA.
Which reminds me…I should change out that buffer spring after 30 some years.

It shoots great with 77gr match ammo at my altitude.

I finally got around to changing the bolt group and front take down pin. I launched the detent on the first try but luckily found it

The offending parts





Can anyone tell if the trigger pins are the larger ones?











1/9 twist, so lighter boolets?





The missing bayonet lug doesn't bother me but the missing flash hider kinda does. I don't think I will spend the money to machine it, is there a clamp on device?

I started to put a red dot on it, I bought two Vortex Sparcs from Palmetto for $69 each. Changed my mind, I like the way it's setup. Reminds me a good bit of the A2 I carried for ten years, I think I'm going to leave it and just put a traditional sling on it

quote:

1/9 twist, so lighter boolets?

Depends on where you shoot.

Sea level, maybe 68/69gr or lighter.
At 4700’ elevation, (where I am) 77gr bullets are just fine.

quote:

Originally posted by BigSwede:
1/9 twist, so lighter boolets?

Strictly speaking, the rifling twist rate required for bullet stability is based on the bullet’s length, not weight. A bullet with a lead core will usually be shorter than an all-copper bullet of the same weight, especially one with a deep hollow point.

This is what Bryan Litz has published* about the Sierra 0.224 caliber 77 grain MatchKing bullet:

“Minimum twist required for stability is 1:9.7"
“Recommended twist for optimal performance is 1:8.7" or faster.”

The minimum twist rate is based on “standard” sea level conditions† and 2800 fps muzzle velocity. If the air pressure is lower, the temperature is higher, and/or the humidity is higher, the bullet will be more stable.

* Ballistic Performance of Rifle Bullets, Third Edition, 2017.
† 29.92 in Hg, 59 °F, 0% humidity.

To follow up on the issue of bullet length rather than weight per se affecting its stability in flight with any particular rifling twist rate, I used the Applied Ballistics Quantum app to look up the sea level “stability factor” (Sg) of various 0.224 inch diameter (for example 223 Remington) bullets with a twist of 1:9" and a muzzle velocity of 2600 feet per second. The app states that an Sg of 1.5 or higher provides “comfortable” stability, while 1.0 to 1.5 is “marginal” stability.

Bullets:

75 grain Speer Gold Dot: Sg = 1.58; bullet length 0.933"
Although the weight is only slightly less than 77 grains, one way that it differs from common “match” bullets is its shorter length due to its unsharp meplat (nose shape).

77 grain Sierra MatchKing: Sg = 1.35; bullet length 0.994"

77 grain Berger Tactical OTM: Sg = 1.29; bullet length 1.011"

77 grain Sierra Tipped MatchKing: Sg = 1.11; bullet length 1.064"
Note that the Tipped version of the bullet has a polymer tip which increases its length slightly over the original open tip style, and its stability factor is less.

77 grain Barnes LRX BT: Sg = 0.81; bullet length 1.183"
The LRX is an all-copper bullet with a polymer tip and is significantly longer than the bullets with lead cores.

quote:

Originally posted by BigSwede:
1/9 twist, so lighter boolets?

You'll be fine up to 69 grains. Above that requires some testing.

I had a 1:9 on a 16" AR. FGMM 69 was its favorite factory round, followed by Hornady 55 Vmax. Of course the FGMM 69 rounds bucked the wind better downrange. Accuracy with 73-77 grain loads was variable. Even at my high altitude, it required warmer days to get good results. But I must admit that the single best 5-round group that barrel produced was with FGMM 77.

As they say, every barrel is different. Run a few different loads, and on different days, before settling in with a favorite.

This entire thread was very informative. Thanks to everyone who contributed. The first AR I ever shot was a 20 inch HBAR and I swear it was probably the most accurate rifle I had ever shot.