AR Thread

[Rushy]

I had an Nea break one as well.

What was the cause? After how much use?

[scaggly]

What was the cause? After how much use?

Digit might be able to chime in here, but as far as I know it was only the very early 1st gen NEA's that had any issues with this. I know personally of one NEA bolt that spat a bolt lug, but that was at a reasonably high round count, and losing lugs is a hazard with AR bolts from a variety of manufacturers from what I've read online. The great thing is that unlike all the other brands in NZ, NEA has local support so replacement bolts came out overnight under warranty.

I've got a gen2 NEA and I must have put at least 5,000 rounds through it without any issues at all, and from what I've heard this isn't a problem on their newer rifles.

[Rushy]

Thanks Scaggly.

[Beavis]

A friend had a bolt lug fail on a Gen 1 NEA after 500 odd rounds maybe, all suppressed. Was replaced quickly. I typically prefer to buy brands that individually high pressure then MPI test their bolts, for that reason. It takes a long time for a brand to shake a bad reputation in the AR world.

[redbang]

The NEA's have MPI and HPT in their specs now

[gimp]

The NEA's have MPI and HPT in their specs now

They always claimed "HP and MPI tested" but it was disingenuous as it was only batch testing ie 1 from a batch of however many, which not as good of a QC test as individually testing each bolt (but cheaper!)

[EK9132]

Anyone running the Oceania defense samson suppressor and samson rail combo? Having a few issues with massive poi shift 12inch low 5inch left, 6moa after install and only just stopped it contacting due to barrel whip after a big missio with the file taking some meat out from inside the fore end. Any ideas?

Sent from my GT-I8190T using Tapatalk

[res]

Is the barrel nut done up properly?
A mate has that setup with no dramas whatsoever and I have another of his cans with no problem

[scaggly]

They always claimed "HP and MPI tested" but it was disingenuous as it was only batch testing ie 1 from a batch of however many, which not as good of a QC test as individually testing each bolt (but cheaper!)

I was under the impression that the HPT process was basically subjecting the bolt to a proof test, which also has the effect of potentially shortening the overall life of the bolt by quite a margin. I read that the US army found that bolts (even HPT/MPI tested) will begin to crack at 5,000 rounds, and will generally break at 10,000 rounds.

If bolts tend to let go at the same time, I'm not sure if the benefits of HPT stack up, but interested in others views.

[gimp]

I was under the impression that the HPT process was basically subjecting the bolt to a proof test, which also has the effect of potentially shortening the overall life of the bolt by quite a margin. I read that the US army found that bolts (even HPT/MPI tested) will begin to crack at 5,000 rounds, and will generally break at 10,000 rounds.

If bolts tend to let go at the same time, I'm not sure if the benefits of HPT stack up, but interested in others views.

It picks up the bolts with faults that will fail early, well before end of service life. As I understand it. Failing at a predictable interval after many thousand rounds is ok (wearing out), failing at random with low round counts because of metal/machining flaws isn't

[Spanners]

MPI only picks up external faults.
It will only identify a fault that would be apparent via failure in the 1st few firings.
It's great for selling things to people...
govt contract, service, sniper and tactical work too.

[gimp]

It prevents that failure in the first few firings - ie you're not buying a pre-broken gun

[redbang]

Interesting stuff. At the gunsmiths yesdy with new toy, borescoped, and found that it had been fired. Not many he thought, perhaps 10 rounds. So maybe some proof/functional testing goes on as well.

[scaggly]

Out of curiosity (and having a relatively quiet morning ahead), I went and googled it. The best discussion I found was this one HPT and MPI: still viable and necessary or outdated bureaucracy? - Page 15

In a nutshell, some rate the processes citing mil-spec, some don't. A couple of manufacturers chip in, and their rationale is that if the bolt is manufactured using quality steel, quality manufacturing etc., then there is no benefit to MPI or HPT, and that destructive testing (HPT) only reduces the life of the bolt.

Others (but not other manufacturers that I could tell) disagree with this view, but at the end of the day some fairly big names in ARs don't think either process adds much value.

I'm now better educated than I was an hour ago, and it is pretty much settled for me that the two processes aren't needed as long as you're buying parts from a reputable manufacturer.

Of course, if you're machining your own bolt, then some testing might be in order

[Rushy]

Interesting stuff. At the gunsmiths yesdy with new toy, borescoped, and found that it had been fired. Not many he thought, perhaps 10 rounds. So maybe some proof/functional testing goes on as well.

Yep that is interesting. I got a new AR recently and that had obvious signs of having been fired.