contact of the tip of the bullet with the barrel extension feed ramp will cause some marring, that's just physics. It's not usually a problem unless you're re-chambering and ejecting the same round dozens of times which can eventually deform a hollow point.
Are you talking about taking the barrel extension off of your barrel and reinstalling a different barrel extension or buying a new barrel without the barrel extension attached and attaching one with well polished feed ramps? Are you having alignment issues with your feed ramps or are they just rough and need good polishing?
There are a lot of factors that go into that equation, but it is possible with the existing design dependent on the entrance angle of the cartridge. What chambering are you having issues with, which bullet construction, which mags are you using, how new is your rifle, what do the existing feed ramps look like?I was wondering if there exists a design that DOES NOT mar the tip, period. As you say, it's physics/engineering.
No. Not in an AR. The physics of the loading cycle use the nose of the bullet to lead the case into the chamber because of the staggered feed magazine. That is the reason the feed ramps are so small they gouge the shoulder of the case on deeply seated short bullets, they are meant for the bullet nose.I was wondering if there exists a design that DOES NOT mar the tip, period. As you say, it's physics/engineering.
No. Not in an AR. The physics of the loading cycle use the nose of the bullet to lead the case into the chamber because of the staggered feed magazine. That is the reason the feed ramps are so small they gouge the shoulder of the case on deeply seated short bullets, they are meant for the bullet nose.
Even the controlled feed of a 1911 touches the bullet to the feed ramp and barrel hood.
Rest assured, each bullet is being damaged in a reliable and consistent way, as well as being chambered in the same orientation each time.
So, statistically they’re still all the same.
If the tip damage is detrimental to accuracy, how far have you shot to discover this ballistic anomaly?
Conversely, tipped projectiles do not suffer this damage. I hear they no longer melt either…
Pre 94 HBAR likely has rifle feed ramps. When I was building them back then, I would relieve them (barrel extension and upper receiver) more like the carbine feed ramps. A chain saw file bit works pretty well. That likely won't eliminate damage to bullet tips, but I thought it helped.
You can also modify metal mag feed lips to start the bullet point higher. I never felt the need to do that.
Rifle vs carbine or M4 cuts:
View attachment 1090756
This is a reason I use mostly plastic tipped or flat tipped (i.e. Gold Dot, Fusion) bullets in my semiautos...when I first started handloading, one of my first workups was with some cheap pointed soft points that someone donated to me. I was feeding an HK-type rifle. I got a pattern at 200 yds that was 2 small groups in a little figure-8 shape. I was utterly baffled until I ejected a loaded round and noted that the pointed nose was skived off on one side. When it fed from the other position, it skived off the other side. It was very pronounced.
That said, while OTM bullets still exhibited slight deformation from feeding, they never showed the bizzare double grouping phenomenon. I don't think the small deformation of a match BTHP from feeding is enough to significantly effect ballance or concentricity to where it will harm accuracy.
Compared to the square edges of an HK trunion, AR feed ramps are positively dainty in their treatment of bullet tips.
This is a reason I use mostly plastic tipped or flat tipped (i.e. Gold Dot, Fusion) bullets in my semiautos...when I first started handloading, one of my first workups was with some cheap pointed soft points that someone donated to me. I was feeding an HK-type rifle. I got a pattern at 200 yds that was 2 small groups in a little figure-8 shape. I was utterly baffled until I ejected a loaded round and noted that the pointed nose was skived off on one side. When it fed from the other position, it skived off the other side. It was very pronounced.
That said, while OTM bullets still exhibited slight deformation from feeding, they never showed the bizzare double grouping phenomenon. I don't think the small deformation of a match BTHP from feeding is enough to significantly effect ballance or concentricity to where it will harm accuracy.
Compared to the square edges of an HK trunion, AR feed ramps are positively dainty in their treatment of bullet tips.
As long as your feed ramps are aligned well, polishing them well with something like Flitz should eliminate a lot of the friction. Follower angle/trajectory in some magazines are better designed to lessen the problem as well. Try different mags to see which one might feed better.Reading your post and applying some reading comprehension, your last sentence, the marked difference between HK and AR suggests that maybe a skilled tinkerer could come up with an AR feed ramp that is daintier still. That was really my question; has anybody done that. Still, the responses have be really helpful. Thanks!
No. Precisely the opposite, as in, all variables stack together for the ultimate location of impact. Some mean more than others.If one dropped a pristine cartridge (hollow-point, for instance, since they get thoroughly marred) into the chamber, released the bolt and fired it, there would be no detectable difference in ballistics and accuracy from a bullet that had been drastically marred during loading off the magazine?
The ramps in the upper are only 30 degrees off vertical.Pre 94 HBAR likely has rifle feed ramps. When I was building them back then, I would relieve them (barrel extension and upper receiver) more like the carbine feed ramps. A chain saw file bit works pretty well. That likely won't eliminate damage to bullet tips, but I thought it helped.
You can also modify metal mag feed lips to start the bullet point higher. I never felt the need to do that.
Rifle vs carbine or M4 cuts:
View attachment 1090756