PDA

View Full Version : Would under-power cartridges cause the bolt to not lock back?


Mossy Man
06-23-2012, 7:54 PM
on last round?

I was using Federal 5.56 XM193 55grainers, and the rifle functioned perfectly.

I then tried a 100 rounds of TulAmmo .223 62gr HPs because they were cheap.

Every round fired without issue, but they definitely felt weaker than the M193s.

The only difference, was that while using the TulAmmo, two times out of 10 mags the bolt did not hold open on the last shot.

Rifle also has eaten AE223 Tactical 55 grains without issues.

Rifle in question is S&W M&P15 Sport

tomd1584
06-23-2012, 8:02 PM
likely.. what weight buffer are you using?

Mossy Man
06-23-2012, 8:02 PM
the one that came with the rifle, lol

no idea

tomd1584
06-23-2012, 8:04 PM
If it's a heavy buffer, you could do 2 things:

1. use a "carbine" buffer, or...
2. don't use cheap (underpowered) ammo.

donger
06-23-2012, 8:06 PM
The only difference, was that while using the TulAmmo, two times out of 10 mags the bolt did not hold open on the last shot.

Yes. No question about it.

Mossy Man
06-23-2012, 8:12 PM
If it's a heavy buffer, you could do 2 things:

1. use a "carbine" buffer, or...
2. don't use cheap (underpowered) ammo.

wouldn't it come with a carbine buffer (16" carbine length carbine)

Mossy Man
06-23-2012, 8:13 PM
Yes. No question about it.

thanks, i figured as much.

the rounds felt maybe 70% power of the normal 5.56 193's

accuracy was ok.....they seemed to copper foul the feed ramps a little bit

Travis590A1
06-23-2012, 8:21 PM
Tula is crap, I've had nothing but problems with it my Ak punched 20 primers of tula. I've also had over a dozen bad primers for their 9mm. Some people like it. I sure don't.

Mossy Man
06-23-2012, 8:23 PM
ill probably stick to the federal 5.56 m193

best brass value locally

donger
06-23-2012, 8:25 PM
Tula is crap, I've had nothing but problems with it my Ak punched 20 primers of tula. I've also had over a dozen bad primers for their 9mm. Some people like it. I sure don't.

I've shot Tula/Wolf exactly once. Problems with flyers, inconsistent charges, and stuck cases. Not worth it. Pay the little bit extra and buy some quality ammo. Or roll your own.

tomd1584
06-23-2012, 8:28 PM
wouldn't it come with a carbine buffer (16" carbine length carbine)

not necessarily.. Look at the face of the buffer.

http://www.ar15barrels.com/tech/buffer-construction.jpg

http://www.recoilweb.com/wp-content/blogs.dir/33/files/2012/03/ar-15-faqs-buffer-tube-comparison-958x638.jpg

SFgiants105
06-23-2012, 8:30 PM
Tula is pretty bad ammo, IMO. It is one of the only rounds that has given me issues in my AR

Mossy Man
06-23-2012, 8:32 PM
tomd,

my buffer has no markings on it

tomd1584
06-23-2012, 8:35 PM
tomd,

my buffer has no markings on it

then 99.999% it's a standard carbine buffer.

Don29palms
06-23-2012, 9:04 PM
Tulammo is junk.

Mossy Man
06-23-2012, 9:11 PM
despite the less than stellar accuracy and bolt hold open, i'm surprised it functioned so well.

i've read reports of tulammo failing to fire, failing to eject, and otherwise performing incredibly poorly.

so i guess the smith is a trooper by even eating it at all

FMJBT
06-23-2012, 9:52 PM
Had the same issues with the 75 grain Tula as well. My SPR would fail to FTE and double feed about every 3 rounds. The only rifle I have that would reliably cycle with it is my wife's gun that I built with a 14.5 mid length barrel with a Noveske KX3. I think between the smooth chrome lined chamber, mid length gas system and the KX3, it generated enough gas pressure to cycle. The rifle length gas sytem and stainless barrel on the SPR was a definite No-Go. I could also tell right away it was severely underpowered just by the point of impact at 450 yards. Standard M855 and most other 223 rounds hit about 2.5 mils low at 450. The Tula ammo was hitting about 6-7 mils low, I think that stuff might almost be subsonic as it leaves the muzzle :p . Garbage.