Twist rate and bullet weight for FS2000 1:7 twist

Discuss the FN lineup of tactical rifles; the FS2000, SCAR, and the venerable FAL.
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UpandComer
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Twist rate and bullet weight for FS2000 1:7 twist

Post by UpandComer » 17 Nov 2010, 13:16

Kerberos wrote:
UpandComer wrote:
romer522 wrote:I prefer PRVI over federal right now, plus it costs less.

This will be a good sign if the PRVI 75gr drops below 400/1k again.
Okay, now what's the story with grain? Is 75gr better than 55gr? Why?
Read all the info on the below two links, and you'll know what you need. BLUF: "Better" depends on the barrel twist rate, as some barrels are meant to stabilize certain grain rounds, depending on the barrel twist rate. Also, .223 chambered AR-15s, should not be loaded with 5.56mm, as that is NATO spec ammo, and results in a higher chamber pressure...

http://en.wikipedia.org/wiki/.223_Remington" onclick="window.open(this.href);return false;

what's the best barrel/bullet weight combo?

IIRC, 62 grain 5.56 is best in a 1:9 barrel.

http://www.militaryphotos.net/forums/sh ... 035afbc08c" onclick="window.open(this.href);return false;
What about for a FS2000?

Twist rate is 1:7 and I use 55gr.

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blueorison
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Re: Prvi 5.56 M193 1K Round case for $309 with free shipping

Post by blueorison » 17 Nov 2010, 13:32

The platform (ie your FS2000) isn't the most important consideration. You should mostly consider the chamber tolerances and the barrel construction and twist rate.

Since it is a factory rifle, you don't exactly have to worry about chamber tolerances in what you shoot; for the FS2000 it will shoot 5.56 and .223 pressured ammunition.

And since it is a Fabrique Nationale weapon, you KNOW you have a GREAT barrel. For the 1:7 twist rate, you will be able to shoot grains from 40 to 55 to 77grains. Non-issue. You will also be able to shoot 80gr and 90gr loads completely fine, but you will be harder-pressed to find these factory loaded these days, so it isn't likely you will have to worry about anything higher than a 77gr weighted round.

If you are loading heavier VLD/OTM loads like the 80/90/100 (sounds like you don't reload so disregard if so), be very careful with your pressure spikes.

If you have any other questions, feel free to PM me or other senior members, most of the people here know their stuff and are speaking from PERSONAL experience, not something they read ONLINE or from some FORUM.

I have personally shot 80gr and 90gr rounds out of my platform. :) I hope this post has helped you.
Never attribute to malice that which can be explained by stupidity.
The shooter will always matter more than the gear ever will.
Stop relying on others to do the work for you.
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UpandComer
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Re: Prvi 5.56 M193 1K Round case for $309 with free shipping

Post by UpandComer » 18 Nov 2010, 15:38

blueorison wrote:The platform (ie your FS2000) isn't the most important consideration. You should mostly consider the chamber tolerances and the barrel construction and twist rate.

Since it is a factory rifle, you don't exactly have to worry about chamber tolerances in what you shoot; for the FS2000 it will shoot 5.56 and .223 pressured ammunition.

And since it is a Fabrique Nationale weapon, you KNOW you have a GREAT barrel. For the 1:7 twist rate, you will be able to shoot grains from 40 to 55 to 77grains. Non-issue. You will also be able to shoot 80gr and 90gr loads completely fine, but you will be harder-pressed to find these factory loaded these days, so it isn't likely you will have to worry about anything higher than a 77gr weighted round.

If you are loading heavier VLD/OTM loads like the 80/90/100 (sounds like you don't reload so disregard if so), be very careful with your pressure spikes.

If you have any other questions, feel free to PM me or other senior members, most of the people here know their stuff and are speaking from PERSONAL experience, not something they read ONLINE or from some FORUM.

I have personally shot 80gr and 90gr rounds out of my platform. :) I hope this post has helped you.
That's blueorison! What's the advantage of a heavier grain versus a lighter grain or vice versa? Is the 55 grain I'm using ideal, or would you recommend a different grain for best performance?

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blueorison
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Re: Twist rate and bullet weight for FS2000 1:7 twist

Post by blueorison » 18 Nov 2010, 17:34

Heavier grains = more impact/energy on target. For target shooting, it is generally more accurate and your bullet is more stable in flight. That's the short version. As long as you have the right twist (you do), you can use heavier grain such as 77gr, 80gr, 90gr, and 100gr (I'd recommend a 6.+ twist for the 100gr, but 1:7 will handle it fine).
Never attribute to malice that which can be explained by stupidity.
The shooter will always matter more than the gear ever will.
Stop relying on others to do the work for you.
Shoot more, worry less.

UpandComer
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Posts: 164
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Re: Twist rate and bullet weight for FS2000 1:7 twist

Post by UpandComer » 18 Nov 2010, 19:19

blueorison wrote:Heavier grains = more impact/energy on target. For target shooting, it is generally more accurate and your bullet is more stable in flight. That's the short version. As long as you have the right twist (you do), you can use heavier grain such as 77gr, 80gr, 90gr, and 100gr (I'd recommend a 6.+ twist for the 100gr, but 1:7 will handle it fine).
Gotcha. Thanks. So at what range will one notice an accuracy difference? From 25 yards and beyond, or do you have to be shooting 100 yards or more to see increased accuracy? Until I get the 3X FTS magnifier for my FS2000, I'll only be shooting 25 to 75 yards. When I upgrade to 100 yards, would I see an accuracy improvement going from using 55gr to 77gr?

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blueorison
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Re: Twist rate and bullet weight for FS2000 1:7 twist

Post by blueorison » 18 Nov 2010, 19:41

UpandComer wrote:
blueorison wrote:Heavier grains = more impact/energy on target. For target shooting, it is generally more accurate and your bullet is more stable in flight. That's the short version. As long as you have the right twist (you do), you can use heavier grain such as 77gr, 80gr, 90gr, and 100gr (I'd recommend a 6.+ twist for the 100gr, but 1:7 will handle it fine).
Gotcha. Thanks. So at what range will one notice an accuracy difference? From 25 yards and beyond, or do you have to be shooting 100 yards or more to see increased accuracy? Until I get the 3X FTS magnifier for my FS2000, I'll only be shooting 25 to 75 yards. When I upgrade to 100 yards, would I see an accuracy improvement going from using 55gr to 77gr?
Like I said, that was the highly condensed answer :)

At 25-75 yards, you can use the worst factory ammunition and you wont get more than a 1-2 inch deviation from the X you're aiming at.

There are many variables and factors that go into rounds. I'm assuming you're dealing with factory rounds, so that makes it easier to discuss. Good handloads, however, will outperform ANY factory ammunition you buy. So you might want to look into reloading. The way the brass is prepped, the quality and brand of brass used, the powder used, the bullet, the reloading equipment, seating depth of the bullet, crimps, cannelures, primers, etc. all factor into the accuracy of the round downrange.

However, with factory ammunition, this is not your concern per se, as they have been loaded for you and you cannot modify (see: should not modify...) factory ammunition for 5.56/.223.

Just because the round is heavier, does not mean it is a definite candidate for higher accuracy. As I always mandate, correlation does not imply causation. If you buy wolf 75gr, PMC 55gr will still be more accurate than the heavier round. This is because the quality of the wolf 75gr is considerably crap compared to PMC's quality. So the fact that a heavier grain bullet has a better sustained flight path in general doesn't always mean it is more accurate than a lighter grain. One way to understand this is that if any factory loaded a 75gr and 55gr with the correct powder ratios using the same primer and casing specs, the 75 gr will most likely be more accurate at longer distances. However, different mfg's use different brass, powders, etc.

However, most manufacturers WILL reserve the higher grain bullets (which are more expensive) for better quality ammunition that is "match" accurate; that is, more accurate than normal "plinking" ammunition. Thus, heavier grains does usually correlate to match and more accurate rounds. The term "match" doesn't always mean you're getting accurate ammunition, many mfg's just use it as a term to sell their relabeled crap.

I've shot every factory round you can find in the stores, and even those that you can't. I actually just spent a year and hundreds of dollars testing ammunition for the 5.56. If you have any other questions, feel free to ask and I'll do my best to answer them concisely and succinctly.

At this point, shooting at 75 yards, I wouldn't worry about purchasing match ammunition, just shoot what is cheapest and more economical and get your shooting skill level up to where it needs to be for that 100-300yard shot i the future :)

When you do get a chance to shoot 100-300yds, send me a PM and I'll recommend you some good ammunition.

Hope that has cleared things up.
Never attribute to malice that which can be explained by stupidity.
The shooter will always matter more than the gear ever will.
Stop relying on others to do the work for you.
Shoot more, worry less.

UpandComer
Junior Member
Posts: 164
Joined: 13 Sep 2010, 06:11

Re: Twist rate and bullet weight for FS2000 1:7 twist

Post by UpandComer » 19 Nov 2010, 08:48

blueorison wrote:
UpandComer wrote:
blueorison wrote:Heavier grains = more impact/energy on target. For target shooting, it is generally more accurate and your bullet is more stable in flight. That's the short version. As long as you have the right twist (you do), you can use heavier grain such as 77gr, 80gr, 90gr, and 100gr (I'd recommend a 6.+ twist for the 100gr, but 1:7 will handle it fine).
Gotcha. Thanks. So at what range will one notice an accuracy difference? From 25 yards and beyond, or do you have to be shooting 100 yards or more to see increased accuracy? Until I get the 3X FTS magnifier for my FS2000, I'll only be shooting 25 to 75 yards. When I upgrade to 100 yards, would I see an accuracy improvement going from using 55gr to 77gr?
Like I said, that was the highly condensed answer :)

At 25-75 yards, you can use the worst factory ammunition and you wont get more than a 1-2 inch deviation from the X you're aiming at.

There are many variables and factors that go into rounds. I'm assuming you're dealing with factory rounds, so that makes it easier to discuss. Good handloads, however, will outperform ANY factory ammunition you buy. So you might want to look into reloading. The way the brass is prepped, the quality and brand of brass used, the powder used, the bullet, the reloading equipment, seating depth of the bullet, crimps, cannelures, primers, etc. all factor into the accuracy of the round downrange.

However, with factory ammunition, this is not your concern per se, as they have been loaded for you and you cannot modify (see: should not modify...) factory ammunition for 5.56/.223.

Just because the round is heavier, does not mean it is a definite candidate for higher accuracy. As I always mandate, correlation does not imply causation. If you buy wolf 75gr, PMC 55gr will still be more accurate than the heavier round. This is because the quality of the wolf 75gr is considerably crap compared to PMC's quality. So the fact that a heavier grain bullet has a better sustained flight path in general doesn't always mean it is more accurate than a lighter grain. One way to understand this is that if any factory loaded a 75gr and 55gr with the correct powder ratios using the same primer and casing specs, the 75 gr will most likely be more accurate at longer distances. However, different mfg's use different brass, powders, etc.

However, most manufacturers WILL reserve the higher grain bullets (which are more expensive) for better quality ammunition that is "match" accurate; that is, more accurate than normal "plinking" ammunition. Thus, heavier grains does usually correlate to match and more accurate rounds. The term "match" doesn't always mean you're getting accurate ammunition, many mfg's just use it as a term to sell their relabeled crap.

I've shot every factory round you can find in the stores, and even those that you can't. I actually just spent a year and hundreds of dollars testing ammunition for the 5.56. If you have any other questions, feel free to ask and I'll do my best to answer them concisely and succinctly.

At this point, shooting at 75 yards, I wouldn't worry about purchasing match ammunition, just shoot what is cheapest and more economical and get your shooting skill level up to where it needs to be for that 100-300yard shot i the future :)

When you do get a chance to shoot 100-300yds, send me a PM and I'll recommend you some good ammunition.

Hope that has cleared things up.
Thanks! I really appreciate all the info! :clap:

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