.223/5.56 reloading question

Reef · November 7, 2012, 12:32 PM

I recently picked up a Sig M400 that has a 1 in 7 twist. Does anyone have any experience with 55 gr ammo with that twist rate?

Smitty1 · November 7, 2012, 12:47 PM

You need to shoot between a 70 to 75 grain bullet for best results in a fast twist barrel like 1-7. 55 gr. will be to light and fast in that barrel. JMO

Reef · November 7, 2012, 12:49 PM

That is what I was afraid of, thank you for the reply.

Reef

JimDandy · November 7, 2012, 12:50 PM

I've got a colt 6920 and ran some factory .223 through- Federal 100 round value pack from Walmart- for sighting and plinking. It ran just fine. Though I was limited to a 25 yard lane, and used a bipod instead of a full rest I was getting some geat groups, and it sighted in like a dream. I'd also point out the M193 is a 55 grain ball cartridge, though 5.56 rather than .223.

zxcvbob · November 7, 2012, 12:57 PM

Quote:

I recently picked up a Sig M400 that has a 1 in 7 twist. Does anyone have any experience with 55 gr ammo with that twist rate?

Pardon my ignorance, but what's the barrel length? If it's a short barrel, you should give a box of 55's a try before you dismiss them.

And what about 62 grain?

Reef · November 7, 2012, 12:59 PM

16" barrel.

JimDandy · November 7, 2012, 01:03 PM

62 grain would be the M855 and M855A1 the military chose over the M193, according to Wikipedia for humane reasons.

g.willikers · November 7, 2012, 01:08 PM

Doesn't it depend on the bullet?
There's different length bullets for any given weight, depending on the design.
That can make a difference in how a given bullet behaves in any barrel.
A longer 55 grain bullet style might do quite well.

zxcvbob · November 7, 2012, 01:18 PM

Quote:

62 grain would be the M855 and M855A1 the military chose over the M193, according to Wikipedia for humane reasons.

Yes, but (since this is a reloading forum) it is also a popular weight for FMJ bullets without a steel billet in the tip. Homogeneous lead core will in theory anyway give better accuracy.

Jimro · November 7, 2012, 01:53 PM

There are lots of 55gr loads out there. Flat base soft nose spitzer, m193 clones, hollowpoint flat base...

The 1:7 twist will stabilize them just fine. You won't know about accuracy until you try.

Jimro

the led farmer · November 7, 2012, 08:03 PM

55gr in a 1:7 is not "optimum" but it will shoot just fine. Probably better than the average shooter to tell much.

mohr308 · November 8, 2012, 01:52 AM

I have a 1:9 twist 16" barrel, and my best shooters are 65gr SGK's

Johnny Falcon · November 13, 2012, 02:46 PM

I shoot both factory and handloaded 55gr. projectiles out of my 1/7 barrel with great accuracy.

Reef · November 13, 2012, 04:10 PM

Thanks. I've shot around 200 factory rounds and a handful of reloads, all 55gr. with no issues. I had read somewhere about that twist rate causing the smaller bullets to come apart in-flight due to the rotation rate. Hasn't happened.

Reef

warningshot · November 14, 2012, 12:46 AM

1:7 twist and 55 FMJs ~100 yards...No sweat. Have fun.

November 7, 2012, 12:32 PM	#1
Reef Senior Member Join Date: April 29, 2012 Location: East Texas Posts: 105	.223/5.56 reloading question I recently picked up a Sig M400 that has a 1 in 7 twist. Does anyone have any experience with 55 gr ammo with that twist rate? __________________ 1911 is Faster than 911

November 7, 2012, 12:49 PM	#3
Reef Senior Member Join Date: April 29, 2012 Location: East Texas Posts: 105	That is what I was afraid of, thank you for the reply. Reef __________________ 1911 is Faster than 911

November 7, 2012, 12:59 PM	#6
Reef Senior Member Join Date: April 29, 2012 Location: East Texas Posts: 105	16" barrel. __________________ 1911 is Faster than 911

November 7, 2012, 01:08 PM	#8
g.willikers Senior Member Join Date: September 28, 2008 Posts: 10,442	Doesn't it depend on the bullet? There's different length bullets for any given weight, depending on the design. That can make a difference in how a given bullet behaves in any barrel. A longer 55 grain bullet style might do quite well. __________________ Walt Kelly, alias Pogo, sez: “Don't take life so serious, son, it ain't nohow permanent.”

November 7, 2012, 01:53 PM	#10
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	There are lots of 55gr loads out there. Flat base soft nose spitzer, m193 clones, hollowpoint flat base... The 1:7 twist will stabilize them just fine. You won't know about accuracy until you try. Jimro __________________ Machine guns are awesome until you have to carry one.

November 7, 2012, 12:47 PM	#2
Smitty1 Junior Member Join Date: August 21, 2012 Posts: 3	You need to shoot between a 70 to 75 grain bullet for best results in a fast twist barrel like 1-7. 55 gr. will be to light and fast in that barrel. JMO

November 7, 2012, 12:50 PM	#4
JimDandy Senior Member Join Date: August 8, 2012 Posts: 2,556	I've got a colt 6920 and ran some factory .223 through- Federal 100 round value pack from Walmart- for sighting and plinking. It ran just fine. Though I was limited to a 25 yard lane, and used a bipod instead of a full rest I was getting some geat groups, and it sighted in like a dream. I'd also point out the M193 is a 55 grain ball cartridge, though 5.56 rather than .223.

November 7, 2012, 01:03 PM	#7
JimDandy Senior Member Join Date: August 8, 2012 Posts: 2,556	62 grain would be the M855 and M855A1 the military chose over the M193, according to Wikipedia for humane reasons.

November 7, 2012, 08:03 PM	#11
the led farmer Senior Member Join Date: July 8, 2012 Location: so cal Posts: 246	55gr in a 1:7 is not "optimum" but it will shoot just fine. Probably better than the average shooter to tell much.

November 8, 2012, 01:52 AM	#12
mohr308 Senior Member Join Date: January 15, 2012 Location: Western New York Posts: 466	I have a 1:9 twist 16" barrel, and my best shooters are 65gr SGK's __________________ Lock and load, the zombies (democrats) are coming (to take your guns)!

November 13, 2012, 02:46 PM	#13
Johnny Falcon Member Join Date: August 18, 2010 Location: Maine Posts: 66	I shoot both factory and handloaded 55gr. projectiles out of my 1/7 barrel with great accuracy.

November 13, 2012, 04:10 PM	#14
Reef Senior Member Join Date: April 29, 2012 Location: East Texas Posts: 105	Thanks. I've shot around 200 factory rounds and a handful of reloads, all 55gr. with no issues. I had read somewhere about that twist rate causing the smaller bullets to come apart in-flight due to the rotation rate. Hasn't happened. Reef __________________ 1911 is Faster than 911

November 14, 2012, 12:46 AM	#15
warningshot Senior Member Join Date: October 7, 2009 Posts: 995	1:7 twist and 55 FMJs ~100 yards...No sweat. Have fun.

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