Am I imagining this or is there a “chart” for the AR 10 like Rob did for the AR 15? I used search to no avail?
The chart was built around the premise of comparing different AR brands to the actual military spec, to my knowledge. There isn’t really a military spec for an AR-10 that I’m aware of. The focus of an AR-10 chart would have to be different somehow.
Knights (US)
LMT (UK)
That was easy lol
I’d guess you have to add Armalite (Canada)…
Wasnt aware of that.
Due to the larger caliber & format of the 7.62 weapons, they will not see the severe firing schedules of the 5.56. The larger sizes of individual components probably helps in regard to less reported parts failures.
My own opinion is the chart means less if you have a working familiarity with weapons, alloys, and coatings. There are better options now.
For example, why HPT? To ensure some troop doesn’t get handed a POS weapon that will fail immediately upon use. Many professionals will put 500 rds through before carrying for duty… so… A good alloy steel, heat treated, shot peened, and MP’d will have a longer life than one that was overstressed with HPT.
HTP is something that is done on most guns but it is called proof firing.
A visual and headspace inspection is generally done afterward, but not mag particle testing.
The mag particle test is really money that would be better spent on other inspection procedures, and it is only mil-spec for an M4/M16 - not a G36, Sig 550, M14, etc.
What is very useful is gauging everything. You can, for example, have go/nogo gauges that you stick in every pin hole on the lower and the firing pin hole, etc. And go/nogo gauges that you drop the bolt and carrier through.
Companies that do that will actually find bad parts and prevent them from shipping. Companies that mag-particle test will not find bad parts, because, I am told, that no parts ever fail that. So since reality is there is an inspection budget, that is a poor way to spend your time on inspection.
I would more like to see an AR company say “We gauge 23 spots on every AR before shipping” than “We check our bolts with mag particles even though the process has never rejected a part.” It was just something someone put in the spec at the time, and Colt has to do it due to contractual requirements.
Actually from what I was told during my last Colt Armorers trianing they reject 20% of their bolts and barrels after the magoparticle test.
Pat
I’m not sure where this idea that no parts are ever rejected in the MPI process came from.
On the subject of the AR10 Chart, it’s not likely to happen due for the most part to the lack of a military specification for AR10s. I suppose we could apply the M4 spec or the M16 spec to the AR10 but I imagine almost all would come up severely lacking if measured with that yardstick, and it may not be applicable.
I have heard HPT compared to driving a car into a wall to test the bumper. I’m not sure I buy that comparison, or the idea that it necessarily shortens the life of the part. To know for sure one would have to take 100 bolts non-HPT and 100 that have been and run them all to failure. Not sure that’s likely to happen anytime soon.
It is along the right idea, think of it more as having the fat kid climb into the tree house first. If it works for him, it works for the rest. I am also under the assumption that a failure during HPT was more so due to flaws in the bolt, not the load applied from the HPT. I have been trying to create an FEA model to see how the stress is distributed through the bolt but my time at work for that has been limited.
It wouldn’t be that hard to chart the differences & similarities of the various AR308s.
One important item would be magazines. Most use the KAC pattern, at least three use the Armalite pattern, one uses Fal mags and I believe one uses G3 mags.
Another is receiver material. While the majority use 7075 aluminum alloy, Armalite uses 7175 which is a bit tougher than 7075. The chart can show whether the receivers are forged or billet and which uppers are compatible with which lowers.
Barrel material. What alloy steel or stainless steel is used. Weapon weight. If small parts are forged, cast or MIM. Rifle configuration. It could also show proprietary parts and special features.
You don’t need a milspec to create a comparison chart of rifles
FYI only the M110 SASS from our 7.62mm guns gets HPT and MP’d
The M110 Bolt life is around 7,500 rds. The rest of the Mk11’s, and SR-25’s are not HPT’d and have bolt life in excess of 12k – I’ve seen some 17k + bolts.
FYI Canada only has about 24 AR10T’s, hardly what I would call an adopted amount, they where bought on an Immediate Operational Requirement, and had to have 24" barrels :rolleyes:. They will be doing a SASS and SharpShooter program within the next two years.
Makes sense. By the way, thanks for making The Chart! It’s an invaluable resource. It might be possible to do multiple AR-10 charts, say, one versus the L129A1, another versus M110. Then you’d run into the problem of figuring out which of those competing versions is “better”.
Wanting to make a chart for AR-10’s highlights a problem I’ve seen with people mis-applying The Chart, i.e. comparing something that’s not a 5.56-shooting, 14.5" barrel, carbine length DI gas weapon to The Chart and then claiming that the compared weapon is not “good enough”. Maybe it isn’t good enough, but an apples-to-oranges comparison is flawed to begin with.
Clearly, but then there is no standard to which the various rifles are compared. Nothing wrong with that, but it just wasn’t the original intent of the existing M4 Chart.
FYI I think its possible to use the M110 and L129A1 in the same chart. There are more similarities than not.
Of course that chart then skews data in favor of KAC and LMT, but I am okay with that :jester:
How about Noveske and Larue in .308?
Of those who you have info from - what percent of parts gets rejected due to MPI?
I find it hard to believe Colt has a 20% scrap rate on machined bolts and barrels. I have heard that cast parts can have up to a 20% reject rate.
Proofing an established design is not really worth it. Test firing for function is more important.
I strongly believe in gauging parts for conformance to the drawing. I am all about that. It makes baby jesus cry to make parts which are out of print.
But there is no way to chart this. There is no way to really know how good each company is with regard to in-spec parts unless you buy a lot of each of them and check them.
I think I heard that number as well. It’s not like they want do it, they have to do it because of outside inspections and QA.
ON a different note when a manufacturer claims that they haven’t rejected any I get a case of the BS blues.