Gunsmithing Ar10 feed cone dimensions

[flyfisherman246]

I’ve been running a 30 degree feed cone going about .030” deep on ar10 chamber ends with JP extensions. If you go much deeper you’ll be loosing case support. The problem I’m having is getting 6 creedmoors to feed with berger hybrid bullets. The elds feed just fine but that long skinny nose of the hybrid slips through the feed ramp and slams into the back of the barrel below the cone. Does anyone have a feed cone dimension that has proven to work with 6 mm hybrids and they are willing to share? I would imagine .22 creed would be even worse and want to play around with some of those in the future as well. Thanks

 

[flyfisherman246]

Just heard back from JP and they basically told me to pick a different bullet. I guess a better question would be has anyone been able to get the 6mm hybrids to feed? If so what does the feed cone look like? Also what barrel extension was used? Thanks

 

[468shot]

Just heard back from JP and they basically told me to pick a different bullet. I guess a better question would be has anyone been able to get the 6mm hybrids to feed? If so what does the feed cone look like? Also what barrel extension was used? Thanks

I can't help much yet. I just chambered a 6 creedmoor with a JP extension, I cut the feed cone at 45 degrees to .030" depth(case web still completely supported). If the bergers don't feed I don't see many other options. The tenon can't be any longer and the cone can't be any deeper.

I'm contemplating the gas port size for a rifle +3 suppressed. Thinking of trying .0625" to start with.

 

[Badmonkey]

I can't help much yet. I just chambered a 6 creedmoor with a JP extension, I cut the feed cone at 45 degrees to .030" depth(case web still completely supported). If the bergers don't feed I don't see many other options. The tenon can't be any longer and the cone can't be any deeper.

I'm contemplating the gas port size for a rifle +3 suppressed. Thinking of trying .0625" to start with.

Did this 45* feed cone allow for proper feeding? I’m having a similar problem with a .243 and 107smk

 

[468shot]

Did this 45* feed cone allow for proper feeding? I’m having a similar problem with a .243 and 107smk

It would feed, but deformed the bullet tips. I switched to a 6.5 Creedmoor.

 

[Badmonkey]

It would feed, but deformed the bullet tips. I switched to a 6.5 Creedmoor.

I tried to feed a 6.5 round with 147eld by pushing the round out of the magazine with a pen and the tip hit in the same spot. A 308 round with 168eld fed fine.

I guess I’ll work on the feed cone and if I can’t get it to stop setting back my bullets I’ll move on to 6.5creed. What feed cone geometry are you using on the 6.5?

 

[padom]

Here a pic of a Rainier Ultramatch 6.5cm on top with gold extension that had issues feeding 140gr bullets, especially 140 Hybrids. They would stab into the tenon face. You can see its got more of rounded radius and lacks a defined feed cone.

Bottom barrel is one of my custom 6.5cm Bartleins with JP QPQ honed and polished barrel extension.

This barrel has the proper feed cone for 6.5cm and feeds 140s including Berger Hybrids like butter.

 

[47chevycoe]

I had a lilja 308 barrel extension on a 260 that wouldn’t feed well at all. I ended up buying a triune precision extension and chambering a new 260 barrel that has been flawless since.