Non-metallic feedramp revisited

[glennb 0]

After installing my PVC feedramp I took a trip to the range. I managed to get 300 rounds in before dark and frozen fingers took over. I burned through at least two 30 rounds mags at almost a bump fire rate, hoping to produce enough heat to check the bullet guide for any sign of softening. The PVC I ended up using was rated at 185 degrees F, compared to the dark grey schedule 80 PVC rated at less than 100 degrees. Only the breech face was slighly warm, the bullet guide and trunion were cold. Back at home I took a good look for any sign of wear or chipping, and only noticed that the 6-32 flat screw head had a small shiny spot where the bolt must have been just making contact. I pulled the screw out and sanded the head down a bit more. I don't want to countersink the screw hole any more than it is. The guide itself took about 5 minutes to shape, the 1 inch OD fitting (not sure what schedule PVC it is, but it is for hot water applications) cuts easily with a hacksaw and diagonal cutters. I started hacking one out of pipe nipple, but that will be a project for another day (or if it would suddenly be necessary because the plastic ramp fails) I fried the first PVC guide I made when I went to countersink the hole with a new (and very sharp) 1/4" bit, which grabbed the plastic and shot right through the guide. I used a dull 1/4" bit on the second one with good results. Here is a picture of the guide in position:

 

[pistonring8 1]

Wonderful field test report. Thanks!

[IndyArms 10,186]

no doubt!!! good work!! and keep it up!

 

[BlenderWizard 12]

OH! One thing to watch for on PVC is that over time, it will get brittle.

[Onepoint 0]

I think a lot of the reason PVC gets brittle is because of UV exposure, shouldn't be a prblem here.

[BlenderWizard 12]

I think a lot of the reason PVC gets brittle is because of UV exposure, shouldn't be a prblem here.

Not when it is under a house in the dark. Time and heat cause pvc to go brittle. CPVC holds up a little better

[Tokageko 8]

Off hand I'd think it would be the cold that would be more likely to make it brittle, just the little bit of material physics that I remember. The other thing may be overall temperature change, the rate at which it happens, along with frequency and degree.... But I digress.

 

I really just wanted to jump on the band wagon and say congratulations. If it holds up, I think you may have advanced the art of saiga conversion significantly. I may try this project with my 223, just to see how well it works.

[BlenderWizard 12]

Off hand I'd think it would be the cold that would be more likely to make it brittle, just the little bit of material physics that I remember.  The other thing may be overall temperature change, the rate at which it happens, along with frequency and degree....  But I digress.

 

I really just wanted to jump on the band wagon and say congratulations.  If it holds up, I think you may have advanced the art of saiga conversion significantly.  I may try this project with my 223, just to see how well it works.

Sort of a combination I think. When it heats up, it is the coling that makes it brittle i think. And yes, also congratulations.

Edited February 24, 2005 by BlenderWizard

[glennb 0]

This plastic feedramp is still experimental. It would be great to get a few others trying it out and sharing experiences. I have not exposed the ramp to any harsh chemicals like PowderBlast and Gunscrubber. I don't use those at all. It held up to Hoppes #9, and QD contact cleaner which does a great job imitating a degreaser. That PVC may just melt when exposed to one of those other solvents.

[BlenderWizard 12]

I know for sure it will melt when exposed to Lacquer thinner, Acteone, or something like that.

[emr454 1]

I used schedule 90 pvc for mine. It's held in with contact cement and its taken 300 rounds with no roblems. It might have had a little Hoppes No. 9 on it but thats about it. I havent found any pvc particles floating around inside the receiver anywhere, just the damn lacquer flakes from the Wolf ammo I use. I agree that cpvc might work a bit better, well last longer maybe, since it is harder(I think). Anyways, if I have any problems with it I will let everyone know.

 

Eric

[Oldwheat 0]

.....Well, it would seem that case-hardening my steel ramp was overkill! ..............................

[IndyArms 10,186]

LOL!!! maybe so.... but it wont ever wear out!!!

 

 

[hoop762 0]

naw...it NEVER hurts to be overly cautious

[Oldwheat 0]

.....Well, it would seem that case-hardening my steel ramp was overkill! ..............................

<{POST_SNAPBACK}>

 

It's also bolted AND JB welded in... Hope that I never have to remove it ...............................

[lollygagger 1]

I think I've try to make a bullet guide out of limestone. Like, think of the Egyptians...

 

it's got to last forever!

 

Lollygagger

[glennb 0]

The non-metallic feed ramp experiment ended after todays's shooting. Having shot about 600 rounds through the Saiga since installing the guide, I noticed cracks radiating from the screw hole. I am not sure if I over torqued the screw, but I noticed that the radius in the trunion and feed ramp are not a perfect match, and the added stress from forcing the plastic to match is too much for prolonged use. It looks like I will be completeing the pipe nipple based ramp after all.

[pistonring8 1]

Thank you for the updated report. I blew a muzzle break off once. This is whats called a learning process. Good job, thanks.

[Onepoint 0]

Never know until you try, besides the hard part is done with trunion work.

 

 

I didnt use pipe on my 223s, I bent a piece of flat 1/4" steel and ground it down a little with a dremel drum. Its a little thicker and the extra heigth has let me use 5.45 mags unaltered.

[emr454 1]

I bet that if you were to just JB weld it in there you wouldnt have any problems. Thats how mine is. I also shaped mine so that I had to force it in there hard to keep it from coming out. Just make sure that the part of the feed ramp that is closest to the mag well does not stick out too far or else the tips of the bullets will go underneath it and pull it out as the round is stripped from the mag(ask me how I know). Mine has held in nicely since then and is still tight against the trunnion. I have tried to pry it out of there and it didnt budge, so I think it will hold up for a good long while.

[BattleRifleG3 16]

I used a PVC section for a feed ramp years ago. Not a single misfire this whole time. It was supposed to be a temporary fix till I could put a metal one in but so far so good. The wild part is it's just press fit in the space between barrel and trunion.