NEW SPR TROUBLE ON FIRST RANGE TRIP. UPDATE IN OP.

[Hohn]

Every rifle is “piecemeal”— that’s the whole point of interchangeable parts. Otherwise we’d all be dealing with the hand-fit process that 1911 lovers consider art and some us consider obsolete.

I work with parts where tolerances are held to under plus/minus 5 microns. A human hair is typically 100-150 microns thick.

With modern CNC machining centers, holding under a thousandth in most dimensions is cake. Tolerances stacking will not cause fitment issues or function issues.

Think about it this way. In any assembly made of parts there are only three kinds of defects: either the part is improperly designed, part is improperly made, or it’s improperly assembled.

Buying reputable mil spec parts all but rules out bad design or manufacture, leaving only assembly.

In this case, we know assembly is pretty simple and not likely wrong, which leaves only a part that is poorly made or designed.

[MistWolf]

Straight Shooter,

The Young NM carrier body has larger the milspec dimensions so it fits in the upper with tighter clearances. The idea is to reduce play and increase in precision. According fo the guys on the National Match forum, it does nothing to help precision. The carrier is designed to float inside the upper. Less clearance means the carrier is less tolerant of residue, debris and gummed up lube.

Bolt not going into battery when hitting the bolt release is one symptom of a bad recoil spring.

When you get this sorted out, you should get 500 to 1000 rounds of trouble free shooting before experiencing empty cases getting caught in the action. I'll save you trouble and tell you now, THAT problem will be the extractor spring. The fix is to install a new spring from Colt or Sprinco.

[Straight Shooter]

Straight Shooter,

The Young NM carrier body has larger the milspec dimensions so it fits in the upper with tighter clearances. The idea is to reduce play and increase in precision. According fo the guys on the National Match forum, it does nothing to help precision. The carrier is designed to float inside the upper. Less clearance means the carrier is less tolerant of residue, debris and gummed up lube.

Bolt not going into battery when hitting the bolt release is one symptom of a bad recoil spring.

When you get this sorted out, you should get 500 to 1000 rounds of trouble free shooting before experiencing empty cases getting caught in the action. I'll save you trouble and tell you now, THAT problem will be the extractor spring. The fix is to install a new spring from Colt or Sprinco.

SOLID info- thank you MistWolf. I knew the carrier had 30% larger surface contact inside...and is i think either half an ounce, or a full ounce heavier, to help with dwell time. Again- I had a long conversation with a gent Id bet an RC & Moon Pie you would know, & he uses them in Match rifles, as well as few other others who recommended them. Also "supposed" to keep bolt in more alignment when seated. My thinking at the time, was if it is any better why not? Still remins to be seen tho.
GREAT info on the extractor spring, to which I have been wondering...the spring had an insert and donut- I removed the donut, figured the rifle gas system didnt need both. Right, or wrong?
Secondly, even tho it is a new Aero Precision spring...I feel/felt this MAY play into it also...it just doesnt feel "right".
Having said that- what Wolff or Sprinco spring would you recommend?
Ive had a Sprinco in my LMT carbine over 10 years now & she is/has been 101% dead nuts reliable.
I also use Wolff in handguns & another rifle...so I like them both.
Any recommends appreciated- and THANK YOU for the info, again.

[AndyLate]

BCM uses a "stronger than standard" extractor spring in their bolts and I agree with removing the donut. My BCM midlength has been flawlessly reliable without the o-ring for thousands of rounds, clean, dirty, hot, and cold.

Colt and Sprinco make the "best" extractor springs. Sprinco was the easiest for me to find, so that is what I bought. I replace the extractor springs on my Toolcraft and PSA bolts before I fire them (even on the midlength I got from you). The Colt and Sprinco springs don't use the o-ring either.

EDIT - I don't know why I typed such a long post when nothing I said is news to you (you know a good bit more about ARs than I do).

Andy

[Straight Shooter]

BCM uses a "stronger than standard" extractor spring in their bolts and I agree with removing the donut. My BCM midlength has been flawlessly reliable without the o-ring for thousands of rounds, clean, dirty, hot, and cold.

Colt and Sprinco make the "best" extractor springs. Sprinco was the easiest for me to find, so that is what I bought. I replace the extractor springs on my Toolcraft and PSA bolts before I fire them (even on the midlength I got from you). The Colt and Sprinco springs don't use the o-ring either.

Andy

I have done that on my PSA middy too Andy- Im big on quality springs & as I said have used Wolff & Sprinco for many years now.
I have zero worrries on the bolt..and so far I cant find a damn thing wrong with the carrier. More firing needed and will do as I am able. No rush. Going to check Sprinco to see what recoil spring I need today.
BTW- hows that PSA doing?
Im up to or at over 1750 rounds on mine and its been a 100% delight.

[AndyLate]

I have done that on my PSA middy too Andy- Im big on quality springs & as I said have used Wolff & Sprinco for many years now.
I have zero worrries on the bolt..and so far I cant find a damn thing wrong with the carrier. More firing needed and will do as I am able. No rush. Going to check Sprinco to see what recoil spring I need today.
BTW- hows that PSA doing?
Im up to or at over 1750 rounds on mine and its been a 100% delight.

I'm hoping your rifle will just "shoot in" and I suspect it will.

My son and I took his PSA out, fired and zero'ed it (with a M-BUS rear) without issue and it is a smooth shooter. I am really a fan of the 16" midlength platform. My son is happy with it, and of course that is the main thing.

Andy

[Straight Shooter]

I'm hoping your rifle will just "shoot in" and I suspect it will.

My son and I took his PSA out, fired and zero'ed it (with a M-BUS rear) without issue and it is a smooth shooter. I am really a fan of the 16" midlength platform. My son is happy with it, and of course that is the main thing.

Andy

Of course, that IS the main thing. Im so glad brother. I STILL cnt find the dang rear sight I had on that at one time...beats me where it is.
And I too, am really thinkin it will indeed shoot in, cant wait to see what itll do...for a "weird rifle" that was "piecemealed together".

[Todd.K]

Last I checked the Colt extractor spring was the only properly engineered upgrade. Worth sourcing if you feel the need, but you really shouldn’t “need” it on a rifle.

[Hohn]

Last I checked the Colt extractor spring was the only properly engineered upgrade. Worth sourcing if you feel the need, but you really shouldn’t “need” it on a rifle.

What the design flaw in the BCM extractor spring kit?

[georgeib]

Last I checked the Colt extractor spring was the only properly engineered upgrade. Worth sourcing if you feel the need, but you really shouldn’t “need” it on a rifle.

Could you expound on this a bit, please? I know that the Colt gold spring is good to go, but I've also read that so is the BCM one. I've read that the Sprinco may actually be the best as it far outlasts all others.