[Tommydean]

guys I have a colt AR rifle i bought about 1990 sighted it in with a friend back then. well I took it out a month ago for the first time in a long time was shooting at 100 yards, went to check the paper and no holes!?!? ok moved to 50 yards took a few shots
and no holes?!?! WTF!!! took it home cleaned it and it looks ok talked to a friend and he told me 55 grain bullets dont shoot well
out of a 1/7 twist barrel and thats what i have on my colt. should i put a 1/8 or 1/9 twist on my rifle? and i did sight it in with
the same kind of amo back then as now, is there any difference between amo in 1990 and now???
thanks Tom

 

[ron169]

Well, you could shoot the 70+ gr loads which would thrive in a 1:7 twist barrel. I would think that a 55 grain bullet should still hold a grou at 100yards. Especially since not much has changed with the 55 gr loads in the last 40 years.

 

[paulosantos]

My 1:7" shoots the Hornady 55 GR FMJ close to 1MOA at 100 yards. Every barrel is different.

 

[ArtFWTx]

Colt 1:7's run fine with good 55 gr ammo. I have personal knowledge of about a half dozen Colt 1:7 barreled rifles from this vintage that shoot 55 grainers very, very well.

Are your sights dialed way off ? Check your sights: elevation and windage, or scope mounts and the scope itself if you have optics.

What does your bore look like after all the storage?

Everything tight that's supposed to be tight?

What ammo were you using? Did you see bullet impacts to note adjustments needed?

 

[maggiepi]

lol...at least it is consistent.

Did you do a bore sight-in to make sure that your sight-in had not gotten way out of whack.

My NM Service Rifle with a 1 in 7 barreled upper gets outstanding accuracy with 55grn bullets.

MS

 

[borderpatrol]

1/7 usually will shoot all bullet weight from 52 to 80 grains really well. Mine do and actually shoot 52/53 grain bullets better than the 68 thru 77's that "it's suppose to shoot". Were you shooting something like Wolf? I would imagine some foreign "economy" ammunition may be full of surprises.

 

[Clint]

Welcome Tommy!

Sorry you're having trouble.

It's been 20 years, so I'd just laser/optical bore sight the thing and try again at 50 yards.

Most AR setups have a dual zero at 50&200 yards, with a couple inches high at 100 yards.

 

[Tommydean]

my colt is stock no optics. the amo I was shooting was PMC and the rifle has been in my vault for years, its clean no corrision or rust, I live in Colorado so its in a dry climate. the bolt is lubed with slip 2000. im going to give it a try tomarrow see how it works.

 

[CannonCocker]

Anybody else have access to your vault? Probaly just need a new zero.

 

[Tommydean]

went out with the wife today for a day or shooting. colt worked fine. got it on paper at 100 yards. the rifle is in brand new condition. Connoncocker I do need to re-zero, I did notice that the primers were smashed flat. i was using winchester ammo
in 55grn. is this because its brand new? the reason i ask is that i had my DPMS car and has a Kotonics barrel on it bought in April of 08 with me in 6.8 and for some time its been flatening the primers just a little not alot and the swip marks arnt as bad on the back of the cases anymore I have been seeing the ones on my colt were worse. is this because i still need to "break it in"?
Thanks guys
Tom

 

[Machinegun]

My 1:7 Colt shoots 55gr just fine! I am with cannon cocker, I would get back to zero again!

 

[CannonCocker]

went out with the wife today for a day or shooting. colt worked fine. got it on paper at 100 yards. the rifle is in brand new condition. Connoncocker I do need to re-zero, I did notice that the primers were smashed flat. i was using winchester ammo
in 55grn. is this because its brand new? the reason i ask is that i had my DPMS car and has a Kotonics barrel on it bought in April of 08 with me in 6.8 and for some time its been flatening the primers just a little not alot and the swip marks arnt as bad on the back of the cases anymore I have been seeing the ones on my colt were worse. is this because i still need to "break it in"?
Thanks guys
Tom

I would like to see a pic of a flatened primer if possible. Also, a pic of the firing pin. You don't think the pin is bent, right? I zeroed in my new Colt LE 6920 1:7 twist the other day with Remington 55gr and no issues.

Does your AR 15 have the elevation drum? If so, is there a "Z" marking on that drum +2 clicks from 6/3 or 8/3?