300 BLK Feed Ramps

[sureYnot]

This thing feeds pointy, jacketed just fine. Slightly blunt will hang up at the bottom of the feed ramp. Looks like the upper wasn't cut quite right. The upper stands taller than the base of the ramps and isn't as wide either. Thinking about carefully applying the dremel to it. Thoughts? Considerations?

[Gtek]

I have doctored a few over the years and it can be done easily. The problem with the Dremel is sometimes things can happen really fast, and not always a good thing. I use files which are slow but very controlled, the small diamond coated kind (small needle files work too). When ramps are matched go to then wrapping small rods with wet/dry paper and crocus and rounding roll front edges. That lock nut on front of Dremel will scar the POO out of inside of the upper no matter how careful you are, I also have that T-shirt. Mount barrel/upper angled up on something rigid and high enough that you are comfortable and stable underneath and with good light, really does not take that long.

[sureYnot]

Success. Or progress at least. Four dummy rounds fed in a row.
Even the file by hand chewed through pretty quick. Thanks for speaking up.

[mattw]

Can you show progress like you did in the last pic?

[sureYnot]

There are spots I'd like to make look a little better....but you can't put back anything you cut off. So, going to see how the range goes before touching it any more.

[mattw]

Thanks for the pics, I have been needing to work on mine and was not sure where to go with it.

[Texas by God]

Flat nose here we come. Good work.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[sureYnot]

mattw,
I had a half-dozen FTF out of 30 rounds today. All on the left ramp. You can clearly see, in my above post, the difference between the two ramps. I took the file and sand paper back after it a little. Still not an exact match, but I expect improvement. Hopefully will know more tomorrow. Weather dependent.


Texas by God,
Thank you, sir. Here's what I'm pushing though the little lady.

[Gtek]

Looks good! I know you see that 7-8 o'clock on left ramp. A little 320 wet paper about an inch wide piece of quarter sheet on a 1/8"ish dowel. Final polish and VERY light roll break of edges and pretty, pretty she will be. How many grains are those thwackers and how hard you pushing them?

[sureYnot]

Looks good! I know you see that 7-8 o'clock on left ramp. A little 320 wet paper about an inch wide piece of quarter sheet on a 1/8"ish dowel. Final polish and VERY light roll break of edges and pretty, pretty she will be. How many grains are those thwackers and how hard you pushing them?

Oh, yes. I see it, and it bothers me. I'm just being super careful on account of not being able to put back what I take off.
If I could shoot off the back porch, I'd be done. If it works as is, I'll just have to work on conquering my CDO, because I won't touch it again.
These thwackers are 311-122-HPs from NOE. Best group so far is over 19 grains of winchester 296. According to QuickLoad, that's 2146 fps. (no chrony. it's on the wishlist.) That gives me a MPBR of 174 yards on a 4in target and 6in low at 200 yards, which is about as far as I'd want to chuck rocks at a deer with it.
I'm pretty happy with that. I figured 2000 fps would be about the best it would do, accurately.
So far, I'm pleased with the round. I expected less. Penetration/expansion tests will have a say in that.

[sureYnot]

No surprise. Still issues with left ramp. Did some more file and sandpaper work.
Will report back when successful and include pics of working product so someone can benefit from my risk.

Sent from my XT1710-02 using Tapatalk

[sureYnot]

Had to shorten COAL due to one getting stuck. That gave me new problems.
May have found the sweet spot. Found a length that worked on the dummy rounds. Will be a few days before live fire testing.

Sent from my XT1710-02 using Tapatalk

[popper]

Use a file and go slow. Metal is hardened and dremmel will got it hot and you can't quench. Look at some on-line pics of various extensions to see what can be done. Don't change the ANGLE, just the width. Test with lancer BO or some decent mag before going too far. Standard pmags aren't quite right for FP.

[mattw]

mattw,
I had a half-dozen FTF out of 30 rounds today. All on the left ramp. You can clearly see, in my above post, the difference between the two ramps. I took the file and sand paper back after it a little. Still not an exact match, but I expect improvement. Hopefully will know more tomorrow. Weather dependent.


Texas by God,
Thank you, sir. Here's what I'm pushing though the little lady.

That looks great. I have had some luck with the lyman 31141 and that is what I am working to feeding reliably. I am currently using the NOE 152 spire point and it always feeds out of a PMAG. I tried the Lee and my chamber is to tight to run with them as I do not nose size the bullet.

[sureYnot]

Was going pretty good. Then I started getting random short strokes and finally wouldn't extract. Gas block came loose and slid down the barrel. It must have been assembled on a mandatory overtime shift. One bolt was almost falling out.
Reinstalled gas block.
Testing to resume in a few days.

Sent from my XT1710-02 using Tapatalk

[Gtek]

If one is sure block is in perfect alignment, can stake set screws like gas key heads at 180 on top with sharp punch.

[sureYnot]

No more cutting on the ramp/receiver other than some polishing with a bit of 1500 grit paper.
Bought a plastic hex mag. Figured it'd be easier to modify than one of my stamped mags.
The rib doesn't run all the way down. Just a kind of bulge on the top.
Had a failure to feed on every single round up the left ramp. Including the last round, wherein the rib wasn't touching the rounds.
Figured maybe a bad mag. I could move the follower left and right a good bit more than my GI mags.
The failures were different though. Every one was the bolt riding over top of the round.
During the super fun time when my gas block basically fell off, the cases were difficult to extract and primers were a bit flattened. I reasoned that there was a possibility that either the brass was being mashed so hard in the chamber that it was slowing down the bolt and causing short stroke (due to difficult extraction)...or, the bolt was slamming back and bouncing hard enough to beat out the magazine spring. (although I couldn't ignore that it was always the left side)
Lengthened my COAL just a titch and backed off the powder about half a grain.
Tested the mag by running some 223 through it. No problems.
Loaded up some 300 BLK (20 rounds). No feed issues.
Not going to say that I trust it yet. But that's a good sign.
Haven't tested any GI mags yet. But, frankly, I don't really care if they work or not.
I'd just as soon have different mags for use in the different calibers.
Was planning on testing those lancer mags. LGS didn't have any. That'll be next step though, if there are any more problems, before "modifying" any more.
Thanks for the help, ya'll.

[Gtek]

Maybe give a good look at loaded mag straight down into, take note of how much (pigeon toe?) inward angle what is working or not working. My limited experience is once you get around 150's and up this angle becomes kind of critical for reliable feed. Maybe slowly easing charging handle forward and watching pickup and entry for hopefully close to centered landing in ramp.

[sureYnot]

Maybe give a good look at loaded mag straight down into, take note of how much (pigeon toe?) inward angle what is working or not working. My limited experience is once you get around 150's and up this angle becomes kind of critical for reliable feed. Maybe slowly easing charging handle forward and watching pickup and entry for hopefully close to centered landing in ramp.

The hex mags seem to be ok.