Question for the accurized AR-15 crowd...

kthomas · Oct 11, 2024

I have a Falkor Caitlyn that I won at an SHC event many years ago. Some of you here have probably shot this exact rifle.

To mix things up from bolt guns, I decided to make this rifle an "SPR". Today at the range I shot some IMI Razorcore 77 and Blackhills 75 match HP ammo. I shot a lot more IMI than the Blackhills, but both ammo produced groups in the 1.25-1.50 MOA range. One group with the IMI was just barely sub 1 MOA. This rifle has a carbon fiber Proof 16" barrel for those curious.

While I understand these are not bad groups for an AR-15, I was hoping for it to be closer to 0.75-1 MOA. This seems to be wishful thinking at this point. However the barrel is likely way over due for a cleaning, so this may be a factor as well.

But while at the range, I ejected a few rounds that were chambered but unfired, and noticed some pretty deep gouges on the ogive of the bullets. My understanding is that this is caused by the feed lips in the barrel extension. I emailed Falkor, they didn't seem too concerned with it. I know that this is a somewhat normal thing with AR-15's, however I can't help but think that these gouges wouldn't have a fairly dramatic effect on precision. Maybe not as much at 100 yards, but I'm sure further out it would produce pretty noticeable results.

What does the accurized ar-15 crowd do to avoid this issue? Or is this just the reality with AR-15's that we have to live with? @MSTN

hafejd30 · Oct 11, 2024

I have a centurion barreled upper I picked up on here a while back. If you closed the bolt gently it would hang up with the 55 fmj round stuck in the feed ramp. Same as yours only it pinched in there. If you sent it home it would look like yours or it would push the bullet back into the casing a ways

I just took a small hand file and knocked the sharp corners down. Doesn’t hang up at all and runs like a champ now

kthomas · Oct 11, 2024

hafejd30 said:
I have a centurion barreled upper I picked up on here a while back. If you closed the bolt gently it would hang up with the 55 fmj round stuck in the feed ramp. Same as yours only it pinched in there. If you sent it home it would look like yours or it would push the bullet back into the casing a ways

I just took a small hand file and knocked the sharp corners down. Doesn’t hang up at all and runs like a champ now

Does it still engrave the bullet after filing?

Bluedog82 · Oct 11, 2024

Polishing the feed ramps is pretty common for trying to get the most precision out of a rifle.

kthomas · Oct 11, 2024

Bluedog82 said:
Polishing the feed ramps is pretty common for trying to get the most precision out of a rifle.

I'm surprised they don't come from the factory that way. Especially on a $3,300 AR that's designed to " represent a paradigm shift in match-grade accuracy never thought possible on the AR platform" (Falkors words).

I guess this is my ignorance in regards to the world of accurized ar's...

hafejd30 · Oct 11, 2024

kthomas said:
Does it still engrave the bullet after filing?

No. I used a file. Then maybe some sandpaper and then some polish. Just enough to knock of the sharp corner

kthomas · Oct 11, 2024

hafejd30 said:
No. I used a file. Then maybe some sandpaper and then some polish. Just enough to knock of the sharp corner

Excellent.

Sounds like I have a project to do.

Basic user · Oct 11, 2024

Without seeing it my only offering would be a guess. (though, mirror polishing feed ramps does NOTHING past just normal smoothing with rough then fine paper) Though, as for those gouges affecting shot group size, I'd single load a few shot groups worth of rounds to see if my group shrank personally. That would at least diagnose that part of it.
Have any pics of your chamber by the magazine? Have you tried different mags? And have you tried standard ammo? (55/62gr)

357Max · Oct 11, 2024

kthomas said:
But while at the range, I ejected a few rounds that were chambered but unfired, and noticed some pretty deep gouges on the ogive of the bullets. My understanding is that this is caused by the feed lips in the barrel extension. I emailed Falkor, they didn't seem too concerned with it. I know that this is a somewhat normal thing with AR-15's, however I can't help but think that these gouges wouldn't have a fairly dramatic effect on precision. Maybe not as much at 100 yards, but I'm sure further out it would produce pretty noticeable results.

What does the accurized ar-15 crowd do to avoid this issue? Or is this just the reality with AR-15's that we have to live with?

First thing you need to do is figure out if those gouges happened on the way in, or the way out.
When you eject a loaded round in an AR they do not get the benefit of a nice smooth feed ramp. As soon as the projectile clears the chamber the ejector slams it sideways into the lugs on the ejection port side.

Try sending a few home with the bolt release & then eject slowly, as soon as you can get your finger on the brass case push it over to counter the ejector & finish pulling it out.

kthomas · Oct 11, 2024

Here's a picture:

I have a feeling that this is the culprit, it looks like its almost a knifes edge:

kthomas · Oct 11, 2024

357Max said:
First thing you need to do is figure out if those gouges happened on the way in, or the way out.
When you eject a loaded round in an AR they do not get the benefit of a nice smooth feed ramp. As soon as the projectile clears the chamber the ejector slams it sideways into the lugs on the ejection port side.

Try sending a few home with the bolt release & then eject slowly, as soon as you can get your finger on the brass case push it over to counter the ejector & finish pulling it out.

If I gently put a round in the chamber by hand, close the BCG, and then eject, the projectiles don't get the gouge.

It seems the gouge only occurs when the ammo takes a ride across the feed ramps.

357Max · Oct 11, 2024

kthomas said:
If I gently put a round in the chamber by hand, close the BCG, and then eject, the projectiles don't get the gouge.

It seems the gouge only occurs when the ammo takes a ride across the feed ramps.

That being the case then yes I would slightly round over those sharp corners. I automatically do that when building any AR. Don't take too much off though, that reduced size lug already has a heavy load. I use a fine stone followed by polishing rouge on a felt.

357Max · Oct 11, 2024

Here's an example. In this case the upper was poorly matched to the feed ramps. In the second picture you can see the slight round over on that center lug.

frank320 · Oct 11, 2024

Before you take a file and starting making changes, how about shooting 2 groups: First group chambered as you were using existing feed ramp, and a second group where you manually and carefully load each round so they don’t scuff.

If the second group is indeed much better than the first group, only then would I conclude that the feed ramps are the issue…

kthomas · Oct 11, 2024

frank320 said:
Before you take a file and starting making changes, how about shooting 2 groups: First group chambered as you were using existing feed ramp, and a second group where you manually and carefully load each round so they don’t scuff.

If the second group is indeed much better than the first group, only then would I conclude that the feed ramps are the issue…

I think more testing is a good thought. I'll head out to the range again next week.

roostercogburn98 · Oct 11, 2024

My bartlein barreled SPR/DMR will shoot IMI 77 grain moa or better all day. I have never noticed any issues like you have seen either with bullets while chambering. My barrel extension is a White Oak competition length.

Three consecutive 5 shot groups all sub moa, just barely, but they are.

hafejd30 · Oct 11, 2024

Mine wears a white oak and is fairly accurate with 55 hornady steel match

3 and 5 round group at 100 yards

kthomas · Oct 11, 2024

Those rifles are definitely more accurate than mine.

I'm going to take it to the range again next week and do some more shooting and testing with it.

I'll also shoot it with different suppressors and w/o suppressor (not that that will change the bullet engraving).

I can't imagine that the bullet engraving can't be hurting the ballistics, but I also don't know how much of an effect it would make at 100 yards, and perhaps there's a few things going on here.

I definitely feel like this rifle should be shooting better, especially given the components and it's supposed quality.

hafejd30 · Oct 11, 2024

kthomas said:
Those rifles are definitely more accurate than mine.

I'm going to take it to the range again next week and do some more shooting and testing with it.

I'll also shoot it with different suppressors and w/o suppressor (not that that will change the bullet engraving).

I can't imagine that the bullet engraving can't be hurting the ballistics, but I also don't know how much of an effect it would make at 100 yards, and perhaps there's a few things going on here.

I definitely feel like this rifle should be shooting better, especially given the components and it's supposed quality.

Those marks are almost certainly from your feed ramps. I’d test a few rounds just running them from magazine to chamber letting the bolt slam home. Mine were so bad it would move the OAL of the round.

I wouldn’t shoot it through a suppressor until I corrected that. You risk a fragment coming off or bullet coming apart if it’s damaged to much. Yours are not bad but you never know

If you’re looking for accuracy then why even test with the scuffs on the bullets.

If you slowly let the BCG forward you’ll likely feel it hang up on the feed ramp

Obviously test this safely or load dummy rounds without primer/powder

kthomas · Oct 11, 2024

hafejd30 said:
Those marks are almost certainly from your feed ramps. I’d test a few rounds just running them from magazine to chamber letting the bolt slam home. Mine were so bad it would move the OAL of the round.

I wouldn’t shoot it through a suppressor until I corrected that. You risk a fragment coming off or bullet coming apart if it’s damaged to much. Yours are not bad but you never know

If you’re looking for accuracy then why even test with the scuffs on the bullets.

If you slowly let the BCG forward you’ll likely feel it hang up on the feed ramp

Obviously test this safely or load dummy rounds without primer/powder

Good points.

And yeah, anything less than letting the BCG ride into battery from the fully locked back position results in failures to feed, so it does seem that the feed ramps are a big impediment here.

kthomas · Oct 11, 2024

I'm also going to reach out to Falkor again and see what they say.

kthomas · Oct 11, 2024

Oh, and I forgot to answer the mag question.

The mags are 20 round p-mags. I used 3 different 20 round pmags today, and I believe they all did the same thing.

kl3309 · Oct 11, 2024

kthomas said:
I'm also going to reach out to Falkor again and see what they say.

Are you seeing this?

That barrel extension is fooked. If your bolt lugs look OK and you haven't stuck one of them action rod tools in there, then Falkor buggered this up during assembly. Probably jacked up the feed ramps at the same time.

kl3309 · Oct 11, 2024

357Max said:
...In this case the upper was poorly matched to the feed ramps..

View attachment 8522275

That's a non-M4 ramped receiver with an M4 ramped barrel extension. It'll still work.

kthomas · Oct 11, 2024

kl3309 said:
Are you seeing this?
View attachment 8522422
That barrel extension is fooked. If your bolt lugs look OK and you haven't stuck one of them action rod tools in there, then Falkor buggered this up during assembly. Probably jacked up the feed ramps at the same time.

Interesting, good catch.

Bolt lugs look just fine. I do have a reaction rod, used just once on the rifle to change out the muzzle device. So I guess it could've been caused by me, though I don't recall being ham-fisted enough to roll that edge like that. But hey, I've certainly have achieved dumber things before.

Unlike that one edge, I don't see any obvious damage to the feed ramps. What am I missing there?

357Max · Oct 11, 2024

kl3309 said:
That's a non-M4 ramped receiver with an M4 ramped barrel extension. It'll still work.

That is a large frame so M4 may not be the best description & yes having the ramps stepped back is acceptable to some.

This is exactly why I build my own stuff. It's not acceptable to me & I have the ability to fix it so I do.
Never mind the match to lower For @kthomas question. Look carefully at pictures to see how the sharp corners at sides of feed ramp were just slightly blended so it wont score the bullets.

Feeds 156 eol @2.860 like butter.

kl3309 · Oct 11, 2024

kthomas said:
Interesting, good catch.

Bolt lugs look just fine. I do have a reaction rod, used just once on the rifle to change out the muzzle device. So I guess it could've been caused by me, though I don't recall being ham-fisted enough to roll that edge like that. But hey, I've certainly have achieved dumber things before.

Unlike that one edge, I don't see any obvious damage to the feed ramps. What am I missing there?

Whatever was stuck up into the barrel extension looked to have been torqued in both directions to have peened both sides of the recess. To me, that would relegate at least the barrel extension to the dumpster, nevermind trying to polish out the feed-ramps.

Edit: The same tool (not you) that caused the damage to the locking lug recess may have raised an edge on the trailing edge of the feed ramps.

kl3309 · Oct 11, 2024

357Max said:
..Look carefully at pictures to see how the sharp corners at sides of feed ramp were just slightly blended so it wont score the bullets...

Yeah, look at how his 8 o'clock locking lug recess is peened. He's got bigger problems than trying to blend in feed ramps.

kthomas · Oct 11, 2024

kl3309 said:
Whatever was stuck up into the barrel extension looked to have been torqued in both directions to have peened both sides of the recess. To me, that would relegate at least the barrel extension to the dumpster, nevermind trying to polish out the feed-ramps.

Edit: The same tool (not you) that caused the damage to the locking lug recess may have raised an edge on the trailing edge of the feed ramps.

Appreciate you pointing this all out to me. Looks like I need to get this barrel extension squared away.

357Max · Oct 12, 2024

kl3309 said:
Yeah, look at how his 8 o'clock locking lug recess is peened. He's got bigger problems than trying to blend in feed ramps.

Your upper arrow I can't make out enough detail in the pic to make any conclusion.

The lower arrow, it looks like a chip in the lug, but on the mag well side. Cant tell from the pic if this chip/deformation goes all the way through. As long as the bolt lugs pass through the extension lugs smoothly without any drag I'm not throwing a Red flag. It's the back side of the lugs mating surface that really matter. Inspect the matting surface of the bolt lugs & maybe use a bore scope to look at the back side of the extension mating surfaces. As long as that all checks out I'd go forward.

Assuming the above is ok, I'd check head space next. If that's good I'd de-bure the corners that flank the ramps and run it.

I thought Falkor used Saturn barrels?? Maybe this was a one off for the prize table?

Every Proof I've got has been sub moa. Hell even the cheap $200 Proof 16" steel button barrel shoots incredibly well with the IMI 77 Razor Core.

kthomas · Oct 12, 2024

357Max said:
Your upper arrow I can't make out enough detail in the pic to make any conclusion.

The lower arrow, it looks like a chip in the lug, but on the mag well side. Cant tell from the pic if this chip/deformation goes all the way through. As long as the bolt lugs pass through the extension lugs smoothly without any drag I'm not throwing a Red flag. It's the back side of the lugs mating surface that really matter. Inspect the matting surface of the bolt lugs & maybe use a bore scope to look at the back side of the extension mating surfaces. As long as that all checks out I'd go forward.

Assuming the above is ok, I'd check head space next. If that's good I'd de-bure the corners that flank the ramps and run it.

I thought Falkor used Saturn barrels?? Maybe this was a one off for the prize table?

Every Proof I've got has been sub moa. Hell even the cheap $200 Proof 16" steel button barrel shoots incredibly well with the IMI 77 Razor Core.

At this rate I may just send it off to a gunsmith that specializes in AR15's to check over for issues and address, given my lack of knowledge and tools on this specific platform.

For at least some duration, Falkor made this Caitlyn model with carbon Proof barrels. How many they made I'm not sure, but it's certainly not a one off.

Bigskyguy · Oct 12, 2024

You can use Dykem to see where your lugs are making contact. Magic marker will work if nothing else.

db2000 · Oct 12, 2024

kthomas said:
I'm also going to reach out to Falkor again and see what they say.

The response from Falkor, as I feel you believe, is unacceptable. Doing what others have suggested will give you the evidence you need support your claim that they need to correct the issue. You can try and rectify it yourself but is you don’t have experience filing and polishing the ramps (and I don’t know if you do or not) I’d let the pros at Falkor do it. I mean, it’s their precision build. I’d expect them to fix it.

Stone111 · Oct 12, 2024

Addressing your original post...The round was gouged because you ripped it back out of the chamber backwards against the sharp feed ramps... Of course its gouged. Nothing wrong with polishing the feedramps.

kthomas · Oct 12, 2024

db2000 said:
The response from Falkor, as I feel you believe, is unacceptable. Doing what others have suggested will give you the evidence you need support your claim that they need to correct the issue. You can try and rectify it yourself but is you don’t have experience filing and polishing the ramps (and I don’t know if you do or not) I’d let the pros at Falkor do it. I mean, it’s their precision build. I’d expect them to fix it.

It's fair to say I don't have experience polishing ramps on an AR-15. I've never built an AR-15 either.

I have a couple of AR-15s, but I buy them as they are (or in this case win). I'm not a big AR-15 guy, my knowledge is obviously pretty limited.

I appreciate the conversation so far, I'm learning a lot here.

BuildingConceptsllc · Oct 12, 2024

kthomas said:
It's fair to say I don't have experience polishing ramps on an AR-15. I've never built an AR-15 either.

I have a couple of AR-15s, but I buy them as they are (or in this case win). I'm not a big AR-15 guy, my knowledge is obviously pretty limited.

I appreciate the conversation so far, I'm learning a lot here.

I'm not an AR guru either but I have built a few and have some shooters. That said, I don't enjoy building them and fooling with them the way others do. I do enjoy having accurate ones. I'd rather load than tweek an AR, but polishing the feed ramps is pretty easy with some sand paper. There's a type that 3m makes that's on a rubber sheet that I use for my turning stuff in my wood shop that works very well. You can put it around a dowel or any shape you want. I think you could do that and be done in an hour or so and have this issue solved and a better feeding rifle.

I did a little test since I had some bullets that my seater marked up but I knew the standard they would hold from previous testing.

Basically, at 100 it's almost impossible to tell unless you have major bullet damage.

kthomas · Oct 12, 2024

BuildingConceptsllc said:
I'm not an AR guru either but I have built a few and have some shooters. That said, I don't enjoy building them and fooling with them the way others do. I do enjoy having accurate ones. I'd rather load than tweek an AR, but polishing the feed ramps is pretty easy with some sand paper. There's a type that 3m makes that's on a rubber sheet that I use for my turning stuff in my wood shop that works very well. You can put it around a dowel or any shape you want. I think you could do that and be done in an hour or so and have this issue solved and a better feeding rifle.

I did a little test since I had some bullets that my seater marked up but I knew the standard they would hold from previous testing.

Basically, at 100 it's almost impossible to tell unless you have major bullet damage.

Polishing sounds simple enough, that's something I could handle.

But it looks like I have a bigger problem that needs to be addressed, and that's the damaged barrel extension. That's something I'll just have someone else do - perhaps Falkor.

It also seems like there may be other issues going on, given the 1.25 MOA precision I'm currently getting. Your last statement confirms what I believe, that the bullet damage likely isn't causing much precision degradation at 100 yards. It sounds like this gun should be much more capable than 1.25 MOA.

BuildingConceptsllc · Oct 12, 2024

kthomas said:
Polishing sounds simple enough, that's something I could handle.

But it looks like I have a bigger problem that needs to be addressed, and that's the damaged barrel extension. That's something I'll just have someone else do - perhaps Falkor.

It also seems like there may be other issues going on, given the 1.25 MOA precision I'm currently getting. Your last statement confirms what I believe, that the bullet damage likely isn't causing much precision degradation at 100 yards. It sounds like this gun should be much more capable than 1.25 MOA.

Yeah that rifle should shoot better than that but keep in mind, a lot of precision around AR rifles is cherry picked. There's a lot of this ".5 moa" stuff that people say but as you know, the number of shots in a group is the key factor there. You are probably looking at 10 shot groups, which are not going to be .5moa, and especially so if you aren't very proficient at shooting AR's.

I'm not saying your rifle is good enough, I don't think it is but just keep in mind what level of precision is really out there without extremes being done to the rifle which no factory made rifle will have because it cost too much.

kthomas · Oct 12, 2024

BuildingConceptsllc said:
Yeah that rifle should shoot better than that but keep in mind, a lot of precision around AR rifles is cherry picked. There's a lot of this ".5 moa" stuff that people say but as you know, the number of shots in a group is the key factor there. You are probably looking at 10 shot groups, which are not going to be .5moa, and especially so if you aren't very proficient at shooting AR's.

I'm not saying your rifle is good enough, I don't think it is but just keep in mind what level of precision is really out there without extremes being done to the rifle which no factory made rifle will have because it cost too much.

I hear you.

Honestly, I have no expectations of a 0.5 MOA AR-15. I was hoping for 0.75-1 MOA repeatable accuracy.

Perhaps I'm getting a distorted perception of what an accurate AR-15 is supposed to look like, to your point.

BuildingConceptsllc · Oct 12, 2024

kthomas said:
I hear you.

Honestly, I have no expectations of a 0.5 MOA AR-15. I was hoping for 0.75-1 MOA repeatable accuracy.

Perhaps I'm getting a distorted perception of what an accurate AR-15 is supposed to look like, to your point.

Yeah it's really easy to do but yes, .75 - 1moa repeatable accuracy is reasonable and for that level a rifle I'd expect that too

fedupflyer · Oct 12, 2024

kthomas said:
I hear you.

Honestly, I have no expectations of a 0.5 MOA AR-15. I was hoping for 0.75-1 MOA repeatable accuracy.

Perhaps I'm getting a distorted perception of what an accurate AR-15 is supposed to look like, to your point.

Get you self some Federal Gold Match ammo for analysis purposes.
When you start pushing the 77g/75g at the higher velocities such as Razorcore and Blackhills 262, you are giving up some accuracy.
I find that 2 five round groups are easier to analyze.

Jigstick · Oct 12, 2024

FWIW I have a custom White Oak barrel I had spun with an intermediate length system in 223 Wylde. I built it on Seekins billet upper and lower, with a BCM Mlok handguard. Using a Young Manufacturing chrome national match bolt carrier. The gun will shoot sub MOA all day long with 77g SMKs. Your feed ramps are ok? Could be a mag issue too

MaximusDecimusMeidius · Oct 12, 2024

is there any shingling between the feed ramps on the upper and the ramps on the barrel extension?

they should be blended as smooth as possible with as little to no transition between the two as possible

are your rounds sitting too low and feeding too low? could you try different mags to maybe present the rounds higher so they don't jam into the ramps so hard

BurtG · Oct 13, 2024

357Max said:
I thought Falkor used Saturn barrels?? Maybe this was a one off for the prize table?

Saturn cut rifle barrels are really accurate

Can’t find many group pics but : Consistently a way under moa rifle and I’m not even a good shooter.

Load testing when I got the used rifle in :

Testing gas gun match ammo

BurtG · Oct 13, 2024

OP , do you have another semi that shoots well ?

Semis are a whole nother animal in terms of accuracy forgiveness for perfection shooting position

Here’s a Douglas I have when I zeroed it :

Then this group shows what happens when I get lazy especially with follow through

357Max · Oct 13, 2024

@BurtG -
“Can’t find many group pics but : Consistently a way under moa rifle and I’m not even a good shooter.“

Good groups, but tell me about the toilet target LOL.

BurtG · Oct 13, 2024

357Max said:
@BurtG -
“Can’t find many group pics but : Consistently a way under moa rifle and I’m not even a good shooter.“

Good groups, but tell me about the toilet target LOL.

lol not sure I use any box I can find

BurtG · Oct 13, 2024

As far as Proof barrels which I think OP said he has. Most of them are good to very great shooters.

But they are a high volume sho and do turn out a turd now and then

kthomas · Oct 13, 2024

BurtG said:
OP , do you have another semi that shoots well ?

Semis are a whole nother animal in terms of accuracy forgiveness for perfection shooting position

Here’s a Douglas I have when I zeroed it :
View attachment 8523182

Then this group shows what happens when I get lazy especially with follow through
View attachment 8523183

The only other AR-15/semi that I've done accuracy testing with is my SR15 Mod1, which was similar. Around ~1.25-1.50 MOA.

Which is about what I expected with a chrome line barrel that isn't designed around precision.

kthomas · Oct 13, 2024

MaximusDecimusMeidius said:
is there any shingling between the feed ramps on the upper and the ramps on the barrel extension?

they should be blended as smooth as possible with as little to no transition between the two as possible

are your rounds sitting too low and feeding too low? could you try different mags to maybe present the rounds higher so they don't jam into the ramps so hard

I can catch a fingernail where those feed lips connect. There does seem to be slight shingling.

I can have a look at different mags.

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