Twist for 55 grain ammo?

bluesclues said:
All three twist rates will work fine for the 55 grainers.

I think it was an internet myth somewhere that 1/7 wouldn't stablize 55 gr bullets, but I have never seen an issue EVER in my LMT or any of my buddies rifles shooting 55 gr ammo.

I have read it on the interwebs but haven't been able to see in the real world.
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I was out shooting my HK SL8-4 the other day. It was my first time shooting 55 gr MFC ammunition. It quickly became apparent that I couldn't hit the broad side of a barn at 100 yards so I brought my target closer to about 50 yards. After a number of less than impressive shots I went to check my target and I was shocked to find that I was tumbling bullets at 50 yards!! I keep my guns in prime condition so I know the barrel wasn't fouled or anything like that. When I got home I weighed the bullets and found there was as much as .15 of a gram difference between weights. I'm not sure exactly what my barrel twist rate is, but the manual says 178mm, right hand.

Is it normal for bullets to weigh that much different in a box of 20 and what the heck is 178mm, right hand in inches?
 
That's a 1:7 twist.
Quality lighter bullets should do fine in a quick twist barrel. Lesser bullets may not have uniform jackets, and the centerline of the bullet may not coincide with the center of mass.
 
gunnut604 said:
I was out shooting my HK SL8-4 the other day. It was my first time shooting 55 gr MFC ammunition. It quickly became apparent that I couldn't hit the broad side of a barn at 100 yards so I brought my target closer to about 50 yards. After a number of less than impressive shots I went to check my target and I was shocked to find that I was tumbling bullets at 50 yards!! I keep my guns in prime condition so I know the barrel wasn't fouled or anything like that. When I got home I weighed the bullets and found there was as much as .15 of a gram difference between weights. I'm not sure exactly what my barrel twist rate is, but the manual says 178mm, right hand.

Is it normal for bullets to weigh that much different in a box of 20 and what the heck is 178mm, right hand in inches?
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I believe you mean MFS ammo, not MFC.
 
I concur that bullet failure out of 1:7 barrels is a function of bullet construction. I have shot Sierra 40 grain HPs out of a 1:7 barrel with comparable accuracy to my 55 grain FMJ reloads. Nosler 55 grain Ballistic Tips provided essentially the same result.

I also tried some reloads with the Remington 55 grain Power-Lokt bullet. These weren't even on paper at 100 yards. Moving closer showed lots of keyholing and holes with "comet tails". I was even able to capture a bullet disintegration on paper at a distance of 7-10 yards in the form of a large, ragged hole with a grey spray of lead surrounding it. The jacket of these bullets appears to be a heavy plating and what information I can find suggests a light construction for easy fragmentation.
 
Gunnut604, 178mm is 7 inches. So your bbl is a 1/7 right hand twist. And as another poster mentioned, poor bullet construction can mean poor bullet performance. Quality bullets will not suffer these same issues.

As an aside, I have re-loaded Hornady bullets in 45 gr and have had excellent results in my 1/7 AR.
 
silverfoxdj said:
Do they normally specify if steel? or you just take your chances
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If they told you then you wouldn't buy it.

Think of ammo like fuel for your rifle and think of your rifle like your high performance car. If you want performance you don't put regular unleaded into your corvette. You will end up with poor performance, pre-ignition and engine damage, same goes for ammo, if you buy the cheapest crap ammo you can find you can't expect accuracy and if you are unlucky enough to buy ammo with bi-metal bullet jackets then think of it like steel on steel with hard granules of carbon fouling as the lube. You will be lucky to get 8000 rounds down the barrel before it won't even shoot good ammo any more because your rifling is worn smooth.
This is why my motorcycles get premium and my rifles don't shoot Norinco or MFS.
If you want accuracy then you have to pay for it. The price is quality ammo that your barrel likes. You may have to try a few different brands but when you find it then it will be worth the trouble. Shoot bulk for fun plinking and quality stuff when you want performance.
Good luck
 
Is there any bulk ammo available thats shoots well-ish and won't mess up a 1-7? I'm guessing 62 gr. would be the ticket?
 
62 gr will shoot fine. Buy a few different types and see what your gun likes.

Or better yet, (if you don't already) look into reloading. Custom tailored ammo for your rifle(s).

Happy shooting!
 
cr5 said:
Just watch that Norc ammo, run a magnet over the bullet (not the case), if it sticks don't use it. The bi-metal jacket will wear out your barrel very quickly. Twist rate will have little effect on wear.
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It's true that bi-metal jackets will wear out your barrel faster, but it's only really significant after several thousand rounds. How much shooting are you going to do? Unless you're burning through piles of ammo you probably wont notice a difference.

luckygunner.com/labs/brass-vs-steel-cased-ammo/#accuracy
 
raks said:
It's true that bi-metal jackets will wear out your barrel faster, but it's only really significant after several thousand rounds. How much shooting are you going to do? Unless you're burning through piles of ammo you probably wont notice a difference.

luckygunner.com/labs/brass-vs-steel-cased-ammo/#accuracy
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Posted a link to a test that was done with 4 identical rifles using 4 different types of ammo. Long story short the rifles that shot bi-metal jackets and cheap crap surplus had more stoppages and the rifle that shot bi-metal jacketed bullets had the barrel completely shot out after 8000 rounds while the rifle that used federal (American Eagle) had no stoppages and the rifling was still like new after 10000 rounds.

For the couple dollars difference I'll run American Eagle and I will never buy a used gun that has shot norinco or MFS.
Feed it garbage and you can expect garbage performance.

http://www.luckygunner.com/labs/brass-vs-steel-cased-ammo/
Same link Raks posted last page. It's long but worth the read if you care about your rifle and want to know what your cheap ammo is doing to it.
 
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for what its worth, I think those Wolf or Bear or whatever ammo in that test are just a thin wash of copper over steel. the MFS is a copper jacket over a thin steel jacket, over a full lead bullet.

I was skeptical and Wanstalls dissected a bullet for me. they still are quite soft. A magnet does stick to them, but its only a very thin steel component.

The steel casing on the other hand could wear the chamber throat more rapidly, and possibly be detrimental to the ejectors health.
 
Also keep in mind that some indoor ranges (the one on the East side of Edmonton anyway) won't let you on the range with ammo that a magnet will stick to the bullet.
 
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