[M995]

Originally, it was stated that all HK416 parts were expected to last a minimum of 15,000 rounds. For the M27 IAR, the parts life was listed as 10,000 minimum although that may be due to a harsher firing schedule b/c one could expect an IAR to be run harder than an assault rifle. AGR416 posted on another forum that his main armorer said that the current HK416N's bolts last 8000-10,000 rounds depending on firing schedule. That figure seems to be a bit lower than the M27's service life.

I'm just wondering if HK has revised the bolt life of all HK416 variants in production from 15K to 10K or if HK uses different alloys/heat treating processes for the bolts of different HK416 variants (ie HK416N), which would explain the bolt life differences.

 

[AGR416]

Ok, I need to clarify something.

The 8k-10k round count is where they see lugs shear off on some weapons. Not all.

Also, the NDLO sees it as an acceptable number.

The parts life warranty we have from HK is 10k rounds.

 

[M995]

Ok, I need to clarify something.

The 8k-10k round count is where they see lugs shear off on some weapons. Not all.

Also, the NDLO sees it as an acceptable number.

The parts life warranty we have from HK is 10k rounds.

Thanks for the clarification. Would it be accurate to say that bolts last 10K on milder firing schedules and 8K on harsher firing schedules? For the USSOCOM presentation by Lucius Taylor that I posted on another thread in this forum, it was stated that M4A1 bolts will crack @ 3-6K on harsh firing schedules and 6-10K on milder firing schedules. IIRC, on average the M4's bolt life is 6K and I think you said that was Colt Canada's warranty for the C8. Also, do you know at approximately how many rounds a HK416's bolt may crack on harsh and milder firing schedules?

 

[Grumpy]

There is a similar discussion on M4C.net.

 

[M995]

There is a similar discussion on M4C.net.

Can you give me a link?

 

[Grumpy]

Bolt life question. - M4Carbine.net Forums

Inhabited by the usual suspects.

 

[sinlessorrow]

started by yours truly:440:

its actually an interesting study with alot of information that makes it hard to truly pinpoint bolt life from what I gathered.

 

[G3Kurz]

Originally, it was stated that all HK416 parts were expected to last a minimum of 15,000 rounds. For the M27 IAR, the parts life was listed as 10,000 minimum although that may be due to a harsher firing schedule b/c one could expect an IAR to be run harder than an assault rifle. AGR416 posted on another forum that his main armorer said that the current HK416N's bolts last 8000-10,000 rounds depending on firing schedule. That figure seems to be a bit lower than the M27's service life.

I'm just wondering if HK has revised the bolt life of all HK416 variants in production from 15K to 10K or if HK uses different alloys/heat treating processes for the bolts of different HK416 variants (ie HK416N), which would explain the bolt life differences.

This is not a set figure 995. It varies on many factors and changes overtime and based on what documentation you look at. Ammo type AND MANUFACTURER (NATO MIL SEC/SS109/M855 is is not the same everywhere!), cadence, suppressed/unsuppressed, environmental conditions, cleaning methods, etc all play a factor in bolt and component service life. Example would be the USMC M27 IAR. The HK TTD document states 10,000-15,000 rounds MINIMUM for bolt life. The 2004 HK416 LAT results showed NLT 15,000 rounds but then that same gun fired more than 24,000 rounds on the same bolt. The Marines wanted a minumum of 10,000 rounds and are currently getting over 20,000 rounds on M27 bolts. Fire a steady diet of the US M855A1 EPR round with it higher chamber pressure in a 100% suppressed gun and I expect the bolt life will suffer accordingly. you can only get accurate info on this with a test of 3 or more guns under the exact same conditions and even still we have seen different results of the same test conducted at two different locations (say HK GmbH and Crane IN, or Colt Hartford and Fort Bragg NC).
G3Kurz

 

[ptoguy]

Being an engineer who deals with fatigue issues, I'm curious to know how they test these numbers.
When HK or Colt, or whoever, is coming up with their bolt life numbers, do they actually test fire that many rounds at the factory out of several guns to show it?
I'd think they would come up with some sort of fatigue test method using machinery (fatigue test the bolt out of the gun), at least initially, as that is a lot of time and money to shoot that many rounds out of sample guns to show life.
Just curious how HK/Colt/FN etc would actually test this at the factory during R&D. Any idea G3kurz?

 

[Montrala]

Being an engineer who deals with fatigue issues, I'm curious to know how they test these numbers.
When HK or Colt, or whoever, is coming up with their bolt life numbers, do they actually test fire that many rounds at the factory out of several guns to show it?
I'd think they would come up with some sort of fatigue test method using machinery (fatigue test the bolt out of the gun), at least initially, as that is a lot of time and money to shoot that many rounds out of sample guns to show life.
Just curious how HK/Colt/FN etc would actually test this at the factory during R&D. Any idea G3kurz?

I do not know how others, but HK do shoot their stuff to destruction. It is part of (high) price you pay for HK.

 

[G3Kurz]

Being an engineer who deals with fatigue issues, I'm curious to know how they test these numbers.
When HK or Colt, or whoever, is coming up with their bolt life numbers, do they actually test fire that many rounds at the factory out of several guns to show it?
I'd think they would come up with some sort of fatigue test method using machinery (fatigue test the bolt out of the gun), at least initially, as that is a lot of time and money to shoot that many rounds out of sample guns to show life.
Just curious how HK/Colt/FN etc would actually test this at the factory during R&D. Any idea G3kurz?

Yes. It is done by firing rounds down range. That is the only way to know for sure.
For a company like HK it is actually pretty easy as many Govt customers require lot acceptance testing which often require that 1 out of 1000, 5000 or 10,000 units go through endurance firing tests. HK's own Technical Terms of Delivery specifies that for every production lot and a single randomly selected weapon is subjected to the firing of 10,000 rounds. After making 100,000 guns you get a very good data base to set those service life figures. That being said it is interestng how often issues come up with customers that are not seen during factory testing.

Not being an engineer, there are fatigue tests on components and assemlies, like mechanisms that cycle the cocking handle or bolt but any maker worth his weight in salt will back that up with actual firing tests to more closely simulate what actually happens in the weapon.

And Montrala is right. It is the cost to do business for manufacturers that strive to make the very best weapons not just "other ran" guns.

G3Kurz

 

[ptoguy]

Interesting, thanks for the insight.

 

[M995]

Great info as always G3kurz.

 

[sigmax]

Great info as always G3kurz.

+1, great info...