Thursday, May 28, 2015

Going Old School


I came across this comparison of the Colt SP1 and the Colt Sporter Target Model today. Basically, it was a shooting comparison of the A1 versus the A2. This interests me because I am gathering parts to put together a retro semi-auto version of the M16A1 using a combination of new and vintage parts. I also have a Colt A2 upper that I plan to build on later. More on those in a later post.

The video below is from the Military Arms Channel. They were trying to determine which rifle would give tighter groups with 55-grain 5.56 ammo. The SP1 (aka A1) had the 1:12 twist barrel while the Sporter Target Model (aka A2) has the 1:7 twist barrel.  They were using Wolf Gold ammo.





I wonder if he would have gotten better results if he had used something like American Eagle/Federal XM193 5.56 ammo.
at

10 comments:

  1. nguyenhm16May 28, 2015 at 9:52 PM

    Wolf Gold 5.56 is made in Taiwan (probably by the same plant that makes ammo for the ROC military), and is by all accounts as good or better than Federal XM193.

    ReplyDelete
    Replies
    1. John RichardsonMay 29, 2015 at 10:17 AM

      Thanks for that info. I didn't realize that. I confused it with the ordinary steel cased Wolf ammo.

      Delete
  2. DamDocMay 29, 2015 at 10:19 AM

    Hey guys.. pay attention.. Constitutional Carry was approved by the Maine Senate yesterday by a margin that surprised and shook up the demanding mommies and everytowners, even with a lot of Bloomberg money pouring into the state in the form of TV commercials!.. Goes to the House next, and Paul LePage (our great Governor in his second term) has indicated support, and is expected to sign it..

    ReplyDelete
    Replies
    1. John RichardsonMay 30, 2015 at 4:42 PM

      I'm glad to see this coming out of Maine. I remember Maine of the 1970s and 80s being very gun friendly and then I started seeing a change in their politics due to in-migration.

      Delete
  3. ArcherMay 29, 2015 at 1:27 PM

    So a 1:7 twist (or 1:8 or 1:9) doesn't give much (if any) measurable advantage over a 1:12 twist during flight.

    What about the ballistics on impact? Is one or the other more or less likely to yaw after it strikes something harder than paper?

    It won't make much difference for a target rifle, but it might for a varmint or defense rifle.

    ReplyDelete
    Replies
    1. John RichardsonMay 30, 2015 at 4:45 PM

      That's an interesting question. I'm not sure.

      I think yaw was supposed to be one of the positive features of the 5.56 rounds when it was introduced. It was more likely to create bad wounds as it yawed and then broke apart.

      Delete
  4. Old NFOMay 29, 2015 at 9:26 PM

    The slower the twist, the less grain you can shoot without stab problems... 1:12 will stab a 55gr, but not 62gr or better in my experience. 1:9 is minimum to get good performance out of 62gr. 1:7 for 69-77gr

    ReplyDelete
  5. Old NFOMay 29, 2015 at 9:26 PM

    The slower the twist, the less grain you can shoot without stab problems... 1:12 will stab a 55gr, but not 62gr or better in my experience. 1:9 is minimum to get good performance out of 62gr. 1:7 for 69-77gr

    ReplyDelete
  6. AnonymousMay 30, 2015 at 6:07 AM

    Interesting that the open sight rifle version of the AR --Both the SP-1 and the "A2" were as accurate or less accurate at 100 yards than my Izmash AK-103 clone; and nether rife shot "point of aim". I was under the impression that the AR would hit a microbe at 600 yards and kill a charging T - Rex. ---Ray

    ReplyDelete
  7. SeemaJune 1, 2015 at 10:13 AM

    thats amazing going to a shooting school and enjoying there.

    ReplyDelete