Re: Surefire 60 rounders , troubles ?
Is this what you are talking about? May be old news?
gearscout
As far as the ship date of the new mags, Surefire representative Ron Canfield tells us the company has delayed both models if the HCM to make minor changes to the mags to guarantee they function in the broadest number of AR platforms possible. The new ship date is June 30, 2011.
Tolerances vary widely across the spectrum of AR manufactures and while Surefire’s current design works fine in milspec Colt rifles, it runs less reliably in some commercial ARs.
The best we can figure is that the HCM, being based on the USGI service mag, works just fine with M4 and M16 rifles that adhere to Colt’s technology package. Commercial M4 Rifle manufacturers that deviate at all from the spec present a problem for the HCM because they are already using a steeper, M4 style feed ramp (M4 feed ramps are steeper than older M16 feed ramps). Some of these guns also cycle faster and harder which lead to a condition called bullet bounce. I witnessed this firsthand at SHOT Show 2011 when I shot the SF HCM in a brand new LMT rifle that was running a little faster than a milspec Colt M4. At first, I thought the gun was short-stroking, but it turns out it was a case of bullet bounce. Somewhere around round 60 on the second mag, the LMT stopped with the bolt carrier held up about an inch from it’s fully seated position. We switched over to a Colt M4 and carried on through 3 more 100 round mags without a stoppage.
Bullet bounce happens when the top bullet in the magazine is upset as it’s fed. The tip of the bullet hits the steeper M4 feed ramp and bounces back instead of sliding smoothly up and into the chamber. In some fast/hard cycling guns, this can cause bullet setback (the bullet gets pushed back into the casing, reducing OAL) which will turn into a partial bolt override when the shortened round fails to feed. To prevent bullet bounce, Surefire is likely adjusting the lips on the HCM to feed a little more smoothly. This jives with what I was told by Mr. Canfield when he told me, “we’re adjusting the ribs at the top of the magazine to make it compatible with more commercial ARs.”
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2 reviews on Midway
Gregory Davis of Lincoln, AR
3.00 stars
Date Posted: 10/5/2011
I just received two surefire 60 round magazines. My first attempt to run 60 rounds through a magazine resulted in two failures to feed. In both cases after around 30 rounds the springs/follower stopped putting any pressure on the rounds. In both cases I had to remove the magazine and shake a loose round out of the chamber. I could literally shake loose rounds out of the magazine as there was not any pressure to hold them in. Pushing down on the rounds, i.e. compressing the springs/follower several times freed it up to start feeding again. I would not put myself in a situation where I had to depend on these magazines for flawless function.
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Tom F of Fort Worth, TX
2.00 stars
Date Posted: 11/8/2011
Uh Oh! I hope this thing needs breaking in somehow. At round number 34 the follower got stuck. After smacking it a few times it finally went up. But managed to stop after each round until round number 41. Then it ran normally. I hope it starts running or it is back to Midway. Thats too much money to spend on a mag that is not reliable.
