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Posted: 5/18/2005 6:39:24 PM EDT
Well, are they?
Link Posted: 5/18/2005 6:43:49 PM EDT
Link Posted: 5/18/2005 6:48:20 PM EDT
[Last Edit: 5/18/2005 6:49:38 PM EDT by mongo001]

Originally Posted By new-arguy:
Needed? No.



That's true. I have two Bushmaster barreled rifles (no Bushmaster barrels have M4 extensions unless you Dremel them in) that shoot 77gr SMKs all day long without failure due to the round. While nursing new or old, refurbed mags to life, I have seen FTF, but that has nothing to do with the round.
Link Posted: 5/18/2005 6:56:33 PM EDT
I think there is something about this in Black Rifle II but my copy is in the other room and I don't want to get up and look.
Link Posted: 5/18/2005 7:10:44 PM EDT
[Last Edit: 5/18/2005 7:13:03 PM EDT by mongo001]

Originally Posted By StormSurge:
I think there is something about this in Black Rifle II but my copy is in the other room and I don't want to get up and look.



I seem to remember some fuzzy quote about M4 ramps being needed for 77gr loads, but that sounds like BS to me.

Found it here.


"The extended feed ramps were necessary to ensure that the thin-jacketed 77-grain Match King bullets were not damaged during the feeding cycle."


While not the resident expert on the issue, this makes absolutely no sense to me.
Link Posted: 5/18/2005 7:26:43 PM EDT
I feed 77 SMK's in my matchgun which lacks the M4 feed ramps, and I have no problems whatsoever.
Link Posted: 5/18/2005 7:51:41 PM EDT
Thanks. I am reassured.
Link Posted: 5/19/2005 4:14:16 AM EDT
I shoot 77s all day long in my CMP rifle and it has no M4 feedramps...
Link Posted: 5/19/2005 4:24:29 AM EDT
While all my 1/7 twist M4s have the feed-ramps, my CR6724 long range AR15 does NOT.

I have been using Sierra 77grn. SMKs in it since the day I got it with NO problems at all.

Mike

ps - IMO one of the best benefits of M4 ramped rifles is for those, who like myself like to use Wichester 64grn. Power Points and other type of "lead-nosed" rounds. The "ramps" do provide a reduced chance of set-back when experimenting with non-FMJ rounds.
Link Posted: 5/19/2005 10:53:01 AM EDT
[Last Edit: 5/19/2005 10:56:31 AM EDT by Ekie]
When I shot high power service rifle I used 68/69 grain bullets at 200 and 300 yards fed out of the mag. The only malfunction (other then blown primers with my 600 yard load) I ever got with my high power rifles were about 2 failures to feed every 1,000 rounds or so. Of course this always happened during a match. The very tip of the bullet would wedge in between the barrel extension and the receiver. At the time (before any of us knew what a M4 ramp was) Tanks offered a service were they would ramp your extension, but no mods to the receiver. This mod cleared up the failures to feed, and all was well.

This was before the green followers were available, so maybe they would have done the same thing for me?

I don't have much experience with 75/77 grain bullets though, those were "experimental" when I got out of high power.

Any how, low feeding rounds resulting in a failure to feed are the most common malfunctions I have ever had with AR's (discounting Wolf ammo of course). Once I even had a FMJ bullet stub between the extension and receiver.
Link Posted: 5/19/2005 11:23:33 AM EDT
Link Posted: 5/19/2005 12:00:13 PM EDT
Link Posted: 5/19/2005 3:44:01 PM EDT

Originally Posted By mongo001:

Originally Posted By StormSurge:
I think there is something about this in Black Rifle II but my copy is in the other room and I don't want to get up and look.



I seem to remember some fuzzy quote about M4 ramps being needed for 77gr loads, but that sounds like BS to me.

Found it here.


"The extended feed ramps were necessary to ensure that the thin-jacketed 77-grain Match King bullets were not damaged during the feeding cycle."


While not the resident expert on the issue, this makes absolutely no sense to me.



According to the "Black Rifle 2" the M4 feed ramps were designed because the M855 was having failures to feed in the M4. It was suspected that higher cyclic rates and the shape of the M855 were the cause. The M193 is more "rounded" according to the book.
Link Posted: 5/23/2005 8:48:11 PM EDT
Link Posted: 5/23/2005 9:27:19 PM EDT
So, it was because of the ogive on the M-855 that the ramps were adopted? And only on the M-4?
Link Posted: 5/23/2005 9:47:47 PM EDT
Link Posted: 5/24/2005 10:33:19 AM EDT
Link Posted: 5/24/2005 11:08:48 AM EDT

Originally Posted By mongo001:

I have two Bushmaster barreled rifles (no Bushmaster barrels have M4 extensions unless you Dremel them in) that shoot 77gr SMKs all day long without failure due to the round. While nursing new or old, refurbed mags to life, I have seen FTF, but that has nothing to do with the round.



Are those both 1/9 twist? And if so, how is accuracy with the heavier bullets?
Link Posted: 5/24/2005 11:37:23 AM EDT
[Last Edit: 5/24/2005 11:41:06 AM EDT by mongo001]

Originally Posted By mattjedi:

Originally Posted By mongo001:

I have two Bushmaster barreled rifles (no Bushmaster barrels have M4 extensions unless you Dremel them in) that shoot 77gr SMKs all day long without failure due to the round. While nursing new or old, refurbed mags to life, I have seen FTF, but that has nothing to do with the round.



Are those both 1/9 twist? And if so, how is accuracy with the heavier bullets?



Nope, everything that I own right now is 1/7 twist, except one -

three Colt barrels (two with M4 ramps, one without)

two Bushmaster barrels - one 1/7 chrome lined HBAR and one 1/8 DCM heavy barrel (neither have M4 ramps)

one White Oak 1/7 stainless barrel (I Dremel'd the ramps into this one (to date, my only Dremel ramp job)- )

one Lilja 1/7 stainless barrel (with M4 ramps).
Link Posted: 5/24/2005 11:42:28 AM EDT
My hand rolled 77gr noslers feed like butter. No problems and no ramps.



Link Posted: 5/24/2005 8:14:14 PM EDT

Originally Posted By ian187:
My hand rolled 77gr noslers feed like butter. No problems and no ramps.






This is good news...
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