1:8 5R barrel cut down?

[Milky]

Has anyone shortened their 1:8 5R barrel from 16" to 14.5" (pinned and welded muzzle devise).

If so did it affect accuracy? I have been interested in doing this but am leery due to the progressive twist rate. From what I understand the barrel starts as a 1:9 and ends in a 1:7 averaging it out to a 1:8 (I could be wrong).

I have no problem with a 1:9 twist as I mainly use 55g ammo, but with it being a progressive twist rate I don't want to muck up the barrel, and it is truly more of an aesthetic upgrade rather than a function upgrade so affecting accuracy or function in a negative way would not be worth the work.

Anyway would love to hear your thoughts can't seem to find much online about this specific barrel and making it shorter.

 

[JaPes]

Funny you should ask...

http://smith-wessonforum.com/smith-wesson-m-p15-rifles/377732-unusual-m-p-barrel.html

 

[Milky]

JaPes, I actually did come across that post, and just eyeballing it from the pictures, that barrel looks like it's 16".

I could be wrong but I am familiar with how my rifle looks with a 16" barrel and a 9" handguard (and it's very close to the pictures shown, aside from that hand guard looking like it's a 10").

Really concerned with affecting the barrels performance by cutting it down. In theory it should be fine, just hopping for a definitive "yeah good to go" or "No your rifle will keyhole".

Typically I shoot out to 100m (99% of the time) but like knowing I have a good stable bullet if I need to go further.

Thanks for the link and the reply!

 

[JaPes]

The one in the picture is a 15.5".

100m = 328.1 ft. *thinks*

AH! One construction detail of the 1:8 5R barre is that it is a progressive gain twist. The barrel starts out 1:11 or 1:12 and as you approach the muzzle the twist rate increases to 1:8. The thread about this is found here.

Depending on where the progressive gain rifling becomes 1:8, shortening the barrel could effectively change the twist rate of the barrel.

Caveat: This is the product of whatever logical thinking I have left after two days of intensive job training. Take it for what it's worth.

 

[Milky]

Yes, exactly my concern!

 

[cyphertext]

Milky, I think you would be the guinea pig... at least on this board. The link JaPes gave you is the first one I remember where a 1:8, 5R barrel had been shortened. Perhaps someone has done it over on AR15.com and can give more info?

 

[Milky]

Thats what I figured. I think going with an new upper would be a better option. I don't want to take the risk of destroying a perfectly fine barrel!