Bi Metal Jacketed Bullets

themalicious0ne · May 21, 2015, 03:15 PM

I seem to have a habit of derailing people's threads so I figured I would start my own. Since I believe this forum is the best place to obtain knowledge from more experienced shooters, I pose this question, at what point does bi metal jacketed bullets start to degrade accuracy to the point of where you are simply throwing lead down range if it wears barrels more at all? Or by what percentage does shooting this type of ammo increase the wear and tear on your barrel, if at all? I am completely inexperienced in metallurgy or shooting this type of ammo whatsoever. It doesn't matter what type of barrel, whether it be cold hammer forged, chrome lined, stainless, nitrided, or melonited.

Some limited examples show it increases wear.

http://www.uspsa.org/front-sight-mag...BiMetal-Ammo-8

http://www.luckygunner.com/labs/bras...el-cased-ammo/

Others say it wont.

https://m.facebook.com/militaryarms/...16101628401641

http://www.ar15.com/forums/t_4_54/15...rrel_life.html

It was also brought up once before, here.

http://thefiringline.com/forums/showthread.php?t=484185

So, do bi metal jacketed bullets make a difference, in rapid fire or slow fire and by how much? Please educate me.

Snyper · May 21, 2015, 08:30 PM

Most of the wear comes from the blasting effect of the hot powder in the throat or forcing cone areas

Jacket materials are softer than steel barrels so they cause very little wear at all

EchoM70 · May 25, 2015, 01:17 AM

Like Snyper said, while I'm sure bullets, bi-metal or not, add a little wear to the barrel it's the powder burning that does the most damage. Biggest example, when accuracy degrades you can have a gunsmith set the chamber back and voila your back to sub-Moa.

It's just something that doesn't affect the barrel enough to lose sleep over. You will harm a barrel much greater by improper cleaning and/or excessive cleaning.

Mobuck · May 25, 2015, 06:27 AM

The "bi" in bi-metal jackets is the outer plating that's supposed to reduce bore wear. How effective is hard to determine. I'm more concerned about the cases since most of the bi-metal bullet ammo is also steel cased, although at this point, I've not had any trouble with my 5.45 AR and all it shoots is steel case.
If your firearm happens to be an AR platform, I wouldn't worry too much-barrels are cheap. If you have a high $$ barrel, I question the logic of using such crappy ammo at all.
I only shoot bi-metal in the 5.45 and 7.62 simply due to supply factors. I don't get the barrels really hot and expect them to last a long time.

Magnum Wheel Man · May 27, 2015, 07:56 AM

I think the replys so far seem to make sense... most good barrels are made out of better steels ( for example muzzle loaders generally use a cheaper ( reads softer ) grade of steel than normal rifle barrels )... I have seen softer grades of barrel steel in rim fire calibers as well...

as posted above... most often barrel wear is centered around throat errosion rather than acual rifling wear... I think with common bimetal bullets the round count would still be pretty high before the rifling would be found as the cause of inaccuracy...

however shooting too hot, & all bets are off... as the bullets would still be at their normal operating temp. but the barrel softer because it's hot... I still think the throat is the 1st to go, even on shooting too hot...

May 21, 2015, 03:15 PM	#1
themalicious0ne Senior Member Join Date: March 13, 2012 Location: Oconomowoc, WI Posts: 345	Bi Metal Jacketed Bullets I seem to have a habit of derailing people's threads so I figured I would start my own. Since I believe this forum is the best place to obtain knowledge from more experienced shooters, I pose this question, at what point does bi metal jacketed bullets start to degrade accuracy to the point of where you are simply throwing lead down range if it wears barrels more at all? Or by what percentage does shooting this type of ammo increase the wear and tear on your barrel, if at all? I am completely inexperienced in metallurgy or shooting this type of ammo whatsoever. It doesn't matter what type of barrel, whether it be cold hammer forged, chrome lined, stainless, nitrided, or melonited. Some limited examples show it increases wear. http://www.uspsa.org/front-sight-mag...BiMetal-Ammo-8 http://www.luckygunner.com/labs/bras...el-cased-ammo/ Others say it wont. https://m.facebook.com/militaryarms/...16101628401641 http://www.ar15.com/forums/t_4_54/15...rrel_life.html It was also brought up once before, here. http://thefiringline.com/forums/showthread.php?t=484185 So, do bi metal jacketed bullets make a difference, in rapid fire or slow fire and by how much? Please educate me.

May 21, 2015, 08:30 PM	#2
Snyper Senior Member Join Date: December 16, 2013 Location: Eastern NC Posts: 3,047	Most of the wear comes from the blasting effect of the hot powder in the throat or forcing cone areas Jacket materials are softer than steel barrels so they cause very little wear at all __________________ One shot, one kill

May 27, 2015, 07:56 AM	#5
Magnum Wheel Man Senior Member Join Date: July 26, 2006 Location: Southern Minnesota Posts: 9,333	I think the replys so far seem to make sense... most good barrels are made out of better steels ( for example muzzle loaders generally use a cheaper ( reads softer ) grade of steel than normal rifle barrels )... I have seen softer grades of barrel steel in rim fire calibers as well... as posted above... most often barrel wear is centered around throat errosion rather than acual rifling wear... I think with common bimetal bullets the round count would still be pretty high before the rifling would be found as the cause of inaccuracy... however shooting too hot, & all bets are off... as the bullets would still be at their normal operating temp. but the barrel softer because it's hot... I still think the throat is the 1st to go, even on shooting too hot... __________________ In life you either make dust or eat dust...

May 25, 2015, 01:17 AM	#3
EchoM70 Member Join Date: April 4, 2012 Posts: 65	Like Snyper said, while I'm sure bullets, bi-metal or not, add a little wear to the barrel it's the powder burning that does the most damage. Biggest example, when accuracy degrades you can have a gunsmith set the chamber back and voila your back to sub-Moa. It's just something that doesn't affect the barrel enough to lose sleep over. You will harm a barrel much greater by improper cleaning and/or excessive cleaning.

May 25, 2015, 06:27 AM	#4
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	The "bi" in bi-metal jackets is the outer plating that's supposed to reduce bore wear. How effective is hard to determine. I'm more concerned about the cases since most of the bi-metal bullet ammo is also steel cased, although at this point, I've not had any trouble with my 5.45 AR and all it shoots is steel case. If your firearm happens to be an AR platform, I wouldn't worry too much-barrels are cheap. If you have a high $$ barrel, I question the logic of using such crappy ammo at all. I only shoot bi-metal in the 5.45 and 7.62 simply due to supply factors. I don't get the barrels really hot and expect them to last a long time.