6.5CM AR10/SR25/AeroM5 bullet damage on feeding

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gilk

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Nov 5, 2009
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#1
I recently built a 20" 6.5CM with a blackhole barrel.
I noticed on feeding the bullets are badly gouged and tips deformed. I contacted BHW and they said it could be a magazine issue since most mags are designed for 308.

Has anyone else seen this issue? If so, what is the solution?

im using gen3 pmags.
 

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#2
You can reduce the damage by using a dremel to smooth out the sharp edges of the feed ramp but some damage is going to occur from being smashed into the feedramp.
 
#3
Im not sure what Im looking at, it looks weird. Is that a picture of the feed ramps and front of chamber looking in through the ejection port??? Both my large frame semis dont look like that.

Both of the below semis are DPMS format. Is my eyes playing tricks on me or does it look like you have teeth on a bolt between the barrel extension teeth and the chamber feed cone? Again, I may just be seeing things but it sure doesnt look like both of my DPMS pattern large format semis....

Here is a Aero M5 receiver with a Wilson Arms 18" 308 barrel. You see the Aero feed ramps and barrel extension then their is a space and the feed cone at the start of the chamber.

[IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/i.imgur.com\/1gQ8zR9.jpg"}[/IMG2]


Here is a MEGA Upper Receiver with a JP barrel extension and Bartlein 22" 6.5cm barrel. Again, looks just like the above Aero/308 setup


[IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/i.imgur.com\/jVSxLMi.jpg"}[/IMG2]
 
#4
padom said:
Here is a MEGA Upper Receiver with a JP barrel extension and Bartlein 22" 6.5cm barrel. Again, looks just like the above Aero/308 setup
[IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/i.imgur.com\/jVSxLMi.jpg"}[/IMG2]
Click to expand...

You gonna blend your feed ramps??
 
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#6
Like has been said, either that is a super weird angle on the picture of that fit isn't quite right. I don't get nearly that kind of damage. My experience is like padom's, here are mine:
 

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#8
Im not sure what's up with that pic at the barrel extension to receiver intersection. It does look odd, I'll have to put the barrel back on tomorrow. Here are some picks of the polish barre tho.

It's an aero M5 upper, should it have ramps that match the feed ramps? I don't remember seeing any but I'll have to check again.
 

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#10
Looks like you got rid of that step on the feed ramps that was present before (or it was an odd camera angle). My M5 upper has feed ramp cuts, but I'm not sure if you can get an M5 without the feed ramp cuts.
 
#11
What weight of bullet? I have had 6.5 cm 140 grain issues where the bullet hit the barrel before the ogive hit the barrel extension. It deformed tips and scratched the bullets. The plastic tip bullets would still load. I had to polish the chamfer on the barrel to get them to ramp in. I think the better fix would be a barrel extension so it hit the ogive.
 
#12
140 eld match

there is a 1/8-3/16" gap between the feed ramps and the beveled edge on the inside of the receiver. Almost like the barrel extension is too short. Is that going cause a problem feeding? Should the receiver be ground to match the feed ramps? They're not even the same angle.
 

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#14
OP - I am thinking a few better pics of the bullets (a few different bullet samples would be great), close ups of the gouges and the tip deformations may help us identify a pattern, which would help to diagnose the ultimate issue.
 
#17
Those things are pretty expensive. I don't really need the extra length in the 6.5CM, tho it would be nice just in case. Are there any other mags that feed reliably and are more affordable?

Has as anyone noticed feeding problems with the pmags or is it just a COL issue for the most part?

 
#19
I polished my feed ramps and all sharp edges in the barrel extension. polished the bcg, bolt face, edges of lugs, extractor, and ejector. I'm still getting the same damage on feeding. See pics. When slow feeding, the bullet goes up the feed ramps and tip hits the back of the barrel and gets stuck before it can enter the chamber. On normal feeding, I'm getting a smashed tip and some scrapes from the feed ramps. Looks like I need to knock that edge down some more on the side of the feed ramps but what do I do about the smashed tips? is it a magazine problem or a barrel problem?
 

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#21
Padom
I've got a very similar issue with a Bartlein spun up by Craddock. Feeds and shoots 140 AMax with excellent results, but am pretty limited to use of poly tipped bullets. Cannot get a Scenar to feed without mashing nose or pushing bullet into case, both of which are unacceptable, of course. BAT extension, polished feed ramps but the feed cone is very small. Tried to polish, but a very confined space. All said, question is whether this is correctable i.e. more cone, without removing extension, or if it had to be removed, index back up to correct headspace and all other dimensions? Know a good smith who could accommodate same?
 
#23
So what's the best way to avoid this situation in the first place? Who makes a barrel that works that doesn't cost $700?
 
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#25
gilk said:
140 eld match

there is a 1/8-3/16" gap between the feed ramps and the beveled edge on the inside of the receiver. Almost like the barrel extension is too short. Is that going cause a problem feeding? Should the receiver be ground to match the feed ramps? They're not even the same angle.
Click to expand...

Try inserting a loaded mag... and with the firing pin removed from the BCG, and see if the rounds hand feed better now( Using the charging handle) .... you might find that the case / bullet does not even make contact with the receivers "ramps".

Also permanent marker a bullet to see if your bullets are contacting the barrels lands...it is kind of odd that you have two visible lines, at about the same location, across the bearing surface on the bullet ... ( to me at least )

On the other hand... those marks, the three of them on the bullet could be from the receivers tiny ramps.


Any marks on the brass case ?


OOPS !! My bad, I didn't see the newer photos... you might need to just ever so slightly polish the breach end of the chamber ( case head end ) just enough to take off any sharp edge.

If it was mine... I would polish the breach face feed cone... Gently ... you can't add material back.

And try a different brand magazine... What Gen. Magpul ?

And if it makes you feel better... My friends SIG 716 had the same issue straight from the factory....
 
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#26
gilk said:
140 eld match

there is a 1/8-3/16" gap between the feed ramps and the beveled edge on the inside of the receiver. Almost like the barrel extension is too short. Is that going cause a problem feeding? Should the receiver be ground to match the feed ramps? They're not even the same angle.
Click to expand...

Take a look at it again guys his Barrel extension is too short, it's about 0.020 off or his Receiver is out of spec, look at the pic from the right side angle, the barrel extension should be flush but for some reason his is set back,and he definitely needs to blend his feed ramps
 
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#28
Also a lot of that bullet damage could be done during extraction the best way to test this is load one bullet by releasing the BCG like you normally would and extract the the round.

Now do the same thing but when you extract the round pull your charging handle really slow and as soon as there's enough room for your finger to get inside and in front of the bolt apply pressure with your finger to the left so it stays straight and doesn't touch any part of your Barrel extension on the way out.

​​​​​​When you extract a round the extractor is going to cause the bullet to slam into the right side of your Barrel extension causing damage, because as soon as the shoulder of the case leaves that chamber the extractor going to force the neck and the bullet to the right hand side under that spring tension.
 
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#29
Gen 3 magpul pmags. AeroM5 enhanced upper.

its definitely the side of the feed ramp that is still too sharp causing the gouging, you can see a little copper on the U section in one of my pictures and the tips are getting smashed on the back face of the barrel. I can smooth out the feed ramps some more no problem but the tip issue may need to be handled by a gunsmith.

I ordered a larue mag to see if that helps but I watched the bullet slide up the feed ramp fine then hang up on the back of the barrel so I don't think it's the mag.

BHW (Columbia river arms)said I could send it in and they replace it if it was out of spec but I'm worried its a design flaw more than a manufacturing defect, in which case they won't refund or replace it.
 
#30
I am having the exact same problem with my Aero Upper, Broughton barrel spun up by Craddock Precision. I am using Gen 3 PMAG, shooting Hornady 140gr ELD-M. If I slowly ride the charging handle the nose of the round is slaming into the back of the barrel. The feed ramps aren't getting the bullet faced into the barrel. It is smashing the side of the polymer tip. I tried switching to 130 Berger Hybrid, and it is doing the same thing. But the Berger doesn't give like the polymer so it is failing to feed.
 
#31
Here are pics of my 6.5 Creedmoor. The first picture of my rifle slow feeding a 130gr Berger OTH. It is slamming flat against the back of the barrel. The second picture shows the barrel and extension. The third is the damage it is doing to the 140gr Hornady ELD-M. Now, I have slammed this one into chamber 3 or so times. So it is exagerating the damage, but shows what it is doing to the polymer tip.
 

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#34
Just FYI, the smashed tip thing can be the bullets slamming back and forth in the magazine before they are ever fed. Here are some pics of some rounds that I was stripping out of an SR25 magazine for my ACC. The first was on top was chambered...all the rest were never cycled.

XSlaK4M.jpg


pUbTHCx.jpg
 
#35
How are the bullets slamming into the inside from of the magazine with such force that it deforms the tip? What is pushing them forward inside the magazine in the first place?? Something isnt right there...I have shot thousands of Hornady tipped bullets in my 3 different 6.5cm semis with KAC mags and never have expereinced that one. Thats a first.
 
#36
padom said:
How are the bullets slamming into the inside from of the magazine with such force that it deforms the tip? What is pushing them forward inside the magazine in the first place?? Something isnt right there...I have shot thousands of Hornady tipped bullets in my 3 different 6.5cm semis with KAC mags and never have expereinced that one. Thats a first.
Click to expand...

Don't know what to tell ya... Every round in the bottom half of that mag had some tip deformation. I went to start single-load the Hornady's because they were not printing well at all compared to my SMK loads. Made the discovery then

KAC ACC w/ Surefire Socom FH and Hornady TAP AMAX factory ammo out of a KAC mag. These rounds were subjected to about 10 rounds before. Without a break and light recoil it can have some thump for a 308 so...
 
#38
Mine is with Josh Kunz at PVA for his counsel and guidance. I can say this, before he's even seen my barrel-he communicates really well and has taken this on, knowing from his experience that this issue exists. My Craddock barrel went back for a fix, fix didn't work, but to either his or Bartlein's credit, it shoots very well with the only thing it will feed.
 
#39
padom said:
How are the bullets slamming into the inside from of the magazine with such force that it deforms the tip? What is pushing them forward inside the magazine in the first place?? Something isnt right there...I have shot thousands of Hornady tipped bullets in my 3 different 6.5cm semis with KAC mags and never have expereinced that one. Thats a first.
Click to expand...

I've had this exact issue on multiple guns. Both semi auto and bolt. I had a .300WM that did it with 208 elds. My current 6mm Creedmoor does it as well.

My guess is under recoil, the magazine and rifle are moving backwards. The rounds might not be tight enough to move with the magazine and instead stay put. Essentially they are sliding forward relative to the magazine.

 
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#40
They are sliding forward a few thousandths of an inch....Its not like they are sliding forward an inch, or 3 inches building up speed. Idk, I have never had this happen in any of my semis but thats just my experience. I actually tested this yesterday with my 308 semi in KAC mags with 168 ELD-M, 6.5cm semi with 140 ELD-M and my 5.56 20" Bartlein with 73 ELD-M. Not a single damaged tip...no clue
 
#41
How does it shoot?

What I see is extraction damage from the extractor forcing the loaded case into the barrel extension lugs from extracting a loaded case out of the chamber. Completely normal in an ar platform.

If you want to find out for yourself ;to test this you need to punch out the roll pin holding the plunger and load a round with no plunger and extract.
 
#42
How does it shoot?

What I see is extraction damage from the extractor forcing the loaded case into the barrel extension lugs from extracting a loaded case out of the chamber. Completely normal in an ar platform.

If you want to find out for yourself ;to test this you need to punch out the roll pin holding the plunger and load a round with no plunger and extract.



its shot ok to not good at all and lower velocity than expected.the bullet tip issue is 100% the barrels fault. The scrape marks are from the barrel extension but I've smoothed that mostly out.

On another note: my 260 with wyatt's detachable mag system blunts my ballistic tips on recoil as well. This is a braked low recoil bolt action rifle.
 
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#43
Sounds like your overall not happy with the barrel.

I'd swap to a kreiger, bartlin, rock...etc.
Could also try a proof research, They sell complete drop in barrels.I built an ar10 with one of their SS barrels not long ago and it's a laser beam and "cheaper" then the other cut rifled barrels in it's competition.
 
#44
Update:

sent the barrel and upper back to BHW and they cut a feed cone in the barrel free of charge. It feeds w/o damaging bullets now. Im very happy with the customer service at Columbia River arms (black Hole weaponry) , tho it should have come with one in the first place.

Feeding problem solved.
 

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