On AR15.com.
What he is saying makes absolutely no sense to me from what I understand about Ti & I've never heard of a hot barrel causing wobbly bullets.
So is he crazy, or what?

His post below in answer to this question:
"Is shooting four magazines rapidly on semi from a 10.5 going to have significant negative impacts on the service life of a Trek-T?

If you say no, I will buy one.[/quote]

The issue is the .223/5.56 ammo. After the bore gets heated up by friction to 8-900 deg F, the bullets destabilize and yaw and pitch, which can cause baffle strikes and damage. The destabilization happens without the suppressor. Many think that this is the result of the bore temp being 800+ degrees, the projectile having a large surface area of copper (which conducts heat well), and the bullet having a relatively small mass of lead (which melts at 625 degrees). It is well documented that even without a suppressor, after around 100 rounds, a 5.56 shot full auto or rapid semi-auto will have the group open dramatically. This does not happen in .308/7.62.

The TREK (both steel and titanium TREK-T) will tolerate a standard M4 firing table (120 rounds -- 4 mags shot as one semi, one burst, one semi, and lastly one full auto).

As I keep saying, the TREK-T (or any of our titanium suppressors) will tolerate heat much better than a stainless one. The issue is the ammo in 5.56 where you need to let the barrel cool.
[/quote]

Link to the thread: http://www.ar15.com/forums/t_6_20/42609 ... tml&page=1

It is true.

Dater is probably the top SME (subject matter expert) in the silencer world. I would listen to the man.

renegade wrote:It is true.

What is true, that titanium handles high heat better than steel, or that hot barrels cause bullet destabilization?
I can think of a bunch of reasons groups would open up with a hot barrel that have nothing to do with bullets leaving the barrel wobbly.

I'm fully aware who Dater is, that's why I asked here. But what he is saying about titanium is contrary to everything I've ever read. At around 815 degrees its strength nosedives well below steel.

bitfi3nd wrote:

renegade wrote:It is true.

What is true, that titanium handles high heat better than steel, or that hot barrels cause bullet destabilization?
I can think of a bunch of reasons groups would open up with a hot barrel that have nothing to do with bullets leaving the barrel wobbly.

I'm fully aware who Dater is, that's why I asked here. But what he is saying about titanium is contrary to everything I've ever read. At around 815 degrees its strength nosedives well below steel.

hot barrels cause bullet destabilization & fragmentation.

I do not know about the Ti thing, but I did see he also used the word alloy, so it might not be 100% Ti.

Destabilization and fragmentation - not saying the man is wrong, but I'm gonna need to see some math on that one. Ambient temp + projectile traveling through a super heated barrel for X time period = Y increase in core temp of the projectile which result in deformation of the projectile in flight. On face, sounds like a bold statement.

Excessive heating = increased barrel whip - sure. In flight deformation of a projectile, esp out of a 10.5"? Maybe, but I'd need to be convinced.

Titanium does not experience a huge drop in strength at high temps. It is used in the compressor stage of modern turbines and can see temps up to 1000 degrees in normal service. The combustion stage of a turbine might see 1800-2000 degrees and needs a nickel or cobalt alloy.

The primary issue with high temperature use of ti is oxidation and much higher chemical reactivity than at room temp. Above 800 degrees grade 5 titanium will begin to oxidize at a higher rate. Over time, this will lead to a lose of base material. With thin walled parts, it could eventually cause a structural failure to occur. Of course the aircraft industry does not use grade 5 ti in turbines. They have much better alloys for that service.

In turbine use, all parts have a lifetime. After the nominal service lifetime is up, the components will be replaced on a rotation. Not really feasible with your can.

As far as the barrel heating goes, I would believe it. I have seen 5.56mm do some crazy things. Hell, you don't even need to heat the barrel up to see some of them. It is a small round fired at high velocity. It is sensitive to even small irregularities. A tiny void in the core can cause a round to careen off target as soon as it leaves the bore.

HandyMan wrote:Titanium does not experience a huge drop in strength at high temps. It is used in the compressor stage of modern turbines and can see temps up to 1000 degrees in normal service. The combustion stage of a turbine might see 1800-2000 degrees and needs a nickel or cobalt alloy.

The primary issue with high temperature use of ti is oxidation and much higher chemical reactivity than at room temp. Above 800 degrees grade 5 titanium will begin to oxidize at a higher rate. Over time, this will lead to a lose of base material. With thin walled parts, it could eventually cause a structural failure to occur. Of course the aircraft industry does not use grade 5 ti in turbines. They have much better alloys for that service.

So, what do you think about this chart linked in that thread?
viewtopic.php?f=10&t=5045

It seems a bit extreme. I am trying to find a chart of tensile properties vs temperature. None of the common manufacturers have one online that I can find.

OK found something. Here is a .pdf from Timet. It has a chart that shows yield and tensile vs temp. At approx. 1000 degrees, it has lost a little less than half it's room temperature strength.

http://www.timet.com/images/document/sh ... AL_6-4.pdf

They have info on a bunch of alloys as well.

Seems pretty straightforward what Dater was saying in the ar15 forums. Certain pure grades of Ti may not match the heat properties of SS, but Gemtech uses their proprietary Ti alloys... which does exceed steel's heat properties.

rimshaker wrote:Seems pretty straightforward what Dater was saying in the ar15 forums. Certain pure grades of Ti may not match the heat properties of SS, but Gemtech uses their proprietary Ti alloys... which does exceed steel's heat properties.

Their alloy isn't proprietary, he even says that they buy it from a named metals supplier & they base their info on what the supplier tells them.

HandyMan wrote: OK found something. Here is a .pdf from Timet. It has a chart that shows yield and tensile vs temp. At approx. 1000 degrees, it has lost a little less than half it's room temperature strength.

http://www.timet.com/images/document/sh ... AL_6-4.pdf

That must be almost exactly what they are using. Still skeptical though.
I'd like to see a video of full auto testing.

rimshaker wrote:Seems pretty straightforward what Dater was saying in the ar15 forums. Certain pure grades of Ti may not match the heat properties of SS, but Gemtech uses their proprietary Ti alloys... which does exceed steel's heat properties.

Ah yes, Gemtech's wonder TI . and that track record for durable cans!

I would also like to point out that strength alone is not a good way to pick an alloy for suppressor use. As the temps go up, you lose other material properties like hardness. Hardness of an alloy is important for peening and erosion resistance.

Superalloys like Inconel are used because they maintain a higher percentage of their room temperature properties than stainless or carbon steel.

Oh, and don't rely on the Cag test to pick a can either. After the test is over, a can that passes would be junk in the civilian market. A pass means that the hunk of s--t left on the end of the gun doesn't cause the host weapon to lose combat effectiveness. It does not mean that the can would be ready for more action.

Doesn't Stellite outperform them all? End of discussion then...get a Saker/Specwar

Dater is usually pretty spot on except his love of 4100 series steel

Handyman got it though . . . oxidation becomes a problem when titanium starts getting really hot and most silencer guys ride them hard and put them up wet.

Kinda the nail on the head, Ti used in turbines get thermo cycled differently and the see a somewhat sheltered existence, I have a coffee can of Compressor turbines from CH-47 turbines that went way past their useful lifespan, When I went to Afghanistan I talked to a few of the Reps on the ground and talked them into giving me some spare blades that they removed from Turbines, the surfaces are coated but only so cracks will show easier and to reflect and dissipate the heat better. They look brand new even though they ingest sand, gravel and see high temps, the key is the fact that they get heat cycled before installation and during their life. Chinooks start engines and go off of APU's for almost an hour before take off then the cycle down for an hour after because it makes them last longer. In Afghanistan they were going over maintenance schedules by thousands of hours, not 10 or 20 like here in the states (Which would be a basis for Court Martial here) How does this transfer? The ti in Aerospace (Intended use originally) is not as extreme as most people think, a suppressor gets much harder use and I dont think its as suitable as other materials. BTW I thought Stelite was brittle! I know there are different grades but I was always told it wasnt suitable around anything to do with heat. (I could be wrong, a Taliban grenade blew 4 years of college away)

The leading edge of the turbine blades on the plane I fly are supposedly titanium(or more likely some kind of titanium alloy) coated for wear resistance. Dont know what the blades themselves are made of. We operate them above 900c(1650+F) during takeoff, I would say mid 800's C is where we operate them for hours upon hours. So Titanium WILL withstand heat, but different parts for different uses IMO. Were not really throwing explosive gasses with possibly small particles in them at them, but super heated, super clean fuel and air(hopefully the air is clean).

I dont know about the heat properties but Stellite is used in the linings of M2 barrels, but from what I understand that is more for wear resistance.

rjacobs wrote:The leading edge of the turbine blades on the plane I fly are supposedly titanium(or more likely some kind of titanium alloy) coated for wear resistance. Dont know what the blades themselves are made of. We operate them above 900c(1650+F) during takeoff, I would say mid 800's C is where we operate them for hours upon hours. So Titanium WILL withstand heat, but different parts for different uses IMO. Were not really throwing explosive gasses with possibly small particles in them at them, but super heated, super clean fuel and air(hopefully the air is clean).

I dont know about the heat properties but Stellite is used in the linings of M2 barrels, but from what I understand that is more for wear resistance.

Back in WW II my buddy's Dad was a machinist in NY City making bearings for submarine propeller shafts
for that very reason.

WIth the equipment of the day it took a skilled person to make the proper cutting
tools, set ups, and then execute. His Dad had to build a canvas surround to shield his set up from the other machinists
to protect his job. At night he would change the arrangements and laugh to himself the next day when he heard
swearing nearby from from the shattering due their copying of his phony rig.