1:9

linthicum

I am just getting in to reloading and reading as much info as possible. I just wanted to verify some info that I am getting. I have a Bushmaster AR15 with a 1:9 20inch barrel. If I am reading everything correct I should be using a 70gr bullet. Now I have 600 rounds of factory 55gr bullets that I have been using.
Question
1. Is 70gr what I should be using.
2. Will it hurt anything (except accuracy) to shot the remainder 55gr bullet that I have.
Thanks linthicum

jtmarine0831

No it won't hurt anything! You will not get optimal accuracy out of the 55s but they will still shoot darn good! Heck I have shot 45grainers out of my 1-9twist AR and they shot pretty darn good(1.75"group @ 100yds). With a .223/5.56mm round twist is a big factor with accuracy, but at its velocity unless you are using real light and extremely thin jacketed bullets they usually won't come apart, unlike the 22-250.


A reply to tailgunner's comment. I was refering to the lighter bullets in faster twist barrels problem of ripping itself apart due to over-oscilation when pushed at too high of a velocity. But you do have another point that I didn't think to mention about the heavier bullets in a slower twist barrel.

Here is a good link to give you a general idea of what twists are ideal for what calibers and weights!

http://www.shilen.com/calibersAndTwists.html

Tailgunner1954

It's not the light bullets in the fast twist that have a problem, it's the heavy bullets in slow twist barrels that DO have problems.

As far as which bullet your rifle prefers, well that's part of the joy of hand loading, as each rifle prefers a slightly different combination.

JT
Your making a good point also, IE a light/thin jacketed bullet out of a fast twist barrel being pushed at "warp factor 9" will come apart due to the high rotational force, but as the OP is talking about a 223....of course if he starts launching 35gr Hornet bullets than he might see the phenomenon we're talking about.

CHEVELLE427

not to high jack this topic ,

Tailgunner1954 wrote

(of course if he starts launching 35gr Hornet bullets than he might see the phenomenon we're talking about.)
my [?][?] is can you shoot hornet tips in the AR, will the OAL be right? or is it just a bad idea all together. asking because i was given 4 boxes of hornet bullets for reloading
im just starting this whole black gun thing
my AR is HB 1/9 223 5.56 stamped

Tailgunner1954

The OAL will be shorter which, if they feed, won't be a problem. You will want to end up with a short section (.020-.050) of "full diameter shank" ahead of the case mouth AND at least .200 of bullet inside the case neck. IOW about the same amount of bullet exposed as you would see if it was in a Hornet case.
What you might see is what used to be called "blue streak" and what looks like a shotgun pattern of fragments hitting the target. Will your gun display this? You'll have to try them and see.
Hornet jackets are thinner, to allow expansion at lower velocities. This combined with high rotational velocities (a product of the twist rate and muzzle velocity) can tear the bullet apart.
The guys that used to see it a lot were the 22-250 and 220 Swift shooters that were trying to see who could get the highest velocities out of their gun. Even than they didn't always see it on every shot.

dcs shooters

I've got a Colt with 1:7 that shoots 55's good out to 200yds. It is not the weight of the bullet, but the length of them.

givette

How 'bout going to an aftermarket bullet maker (Barnes?) and ask if they manufacture 35gr solid bronze bullets? They're longer than lead filled bullets of the same weight.

If length is a problem, and disintigration is a problem, this may very well be the ticket. Joe