AR feed ramp

[aandrews]

Are there after-market feed ramps that don't (as in, DO NOT) mar the tip of a round being fed into the chamber? Like, marring the tip of a hollow-point bullet.

 

[citizenconn]

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?

 

[General Geoff]

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.

 

[aandrews]

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.

I was wondering if there exists a design that DOES NOT mar the tip, period. As you say, it's physics/engineering.

 

[aandrews]

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?

Can grinding/polishing eliminate an contact with the tip in the feeding process??

 

[citizenconn]

I was wondering if there exists a design that DOES NOT mar the tip, period. As you say, it's physics/engineering.

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?

 

[aandrews]

I really can't provide specific information, just that I've noticed in the past, that soft-nosed bullets will be significantly "buggered" have being fed into the chamber. I've also noticed it using hollow-points, the tips of which cannot take rough treatment. And that has got to have a negative effect on flight ballistics. And the rifle was a pre-94 Colt Sporter Match HBAR. But I'd say they all do it.

 

[tarosean]

Most commonly sold AR's were sold with two different kinds of ramps.. you need to be more specific about what you have.

 

[Demi-human]

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…

 

[Varminterror]

Touching the tip and “marring the tip” are very different things in my book.

 

[shoobe01]

It might help the OP to try a sled, load straight inline and see if there's any /functional/ difference in projectile performance.

I have only seen these used for over length cartridges in competition settings but may also solve the actual problem. As it's not really a feed ramp issue but an AR-15 geometry issue as mentioned. You have to avoid a chunk of the feed cycle to avoid the ramp, as the magazine is just too low.

 

[The Glockodile]

...that's just physics.

How about...

...Geometry!

 

[Driftertank]

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.

 

[Cemetery21]

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:

 

[aandrews]

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…

I haven't verified the effect on accuracy; It's just supposition. So your assertion is, since the marring is consistent, it won't affect accuracy? 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?

 

[aandrews]

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

Interesting. Thanks for the tip.

 

[aandrews]

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.

Fusion is what I use, too. I was just curious if tip damage was a valid consideration (it should be, you would think).

 

[aandrews]

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.

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!

 

[citizenconn]

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!

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.

 

[bfoosh006]

FWIW... I would make sure the feed ramps are polished well, including the lug edges around the feed ramp.

Also lightly polish the face of the bolt lugs and bolt face, so the casehead can smoothly / readily slide across it. Think, no binding.

And adjust the cyclic speed to as low as practical. IE , use a Adj. GB or a BRT gas tube sized as needed. limiting the cyclic speed could help make the loading of the round less vigorous.

 

[Demi-human]

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?

No. Precisely the opposite, as in, all variables stack together for the ultimate location of impact. Some mean more than others.

Yes, perfect ammunition would shoot better. But how dramatically is the rifle really damaging the bullets? I’d wager not more than your hold or wind call is degrading hit average or score.

I look at it more as a reduction in overall B.C. of the lot of ammunition, more than a loss of accuracy.
Obviously the AR’s strengths lie in quickly repeatable accurate shots, if not necessarily a razors edge.

So, yeah, it has an effect, probably less so than the reamer that cut your chamber.
It’s totally not going into a 5.56 chamber, right?

 

[AlexanderA]

What you want is a barrel with the deeper "M4" style feed ramps. Most newer barrels have them. The listing should specify the type of feed ramps.

 

[lysanderxiii]

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

The ramps in the upper are only 30 degrees off vertical.