Big Bore Posted January 14, 2009 Share Posted January 14, 2009 Just leave it and keep shooting it..... Link to comment Share on other sites More sharing options...
RiggerJJ Posted January 14, 2009 Share Posted January 14, 2009 I soak my comp in a simple green solution, over night at least, until it just sluffs off with a bit of scraping. sometimes it takes several overnights... jj Link to comment Share on other sites More sharing options...
SharonAnne9x23 Posted January 14, 2009 Share Posted January 14, 2009 it looks like erosion to me. There appears to be a shallow cone of erosion around each port. Is the PMC the yellow box? In the early 90s we tried different ammo at dusk; both through comps and standard A2 flash supressors. With IMR4895 we got a dull glow in the first chamber of a 2 chamber 4 port comp. With the PMC we had bright yellow flames 2 feet to each side of the comp. Very impressive. I wish I could locate the pics. Locally we warned people off of the PMC yellow box .223/5.56 ammo. With the IMR4895 and the A2 suppressor we had no discernable muzzle flash. The malaysian surplus 5.56 made about a 1" flash from the A2. Link to comment Share on other sites More sharing options...
fastshooter03 Posted January 14, 2009 Share Posted January 14, 2009 Pictures look like normal build-up. If you were to let it sit It'd probably have some green in it too. With a round port like that I wonder if you could stick a dremel wire wheel or bronze shotgun brush in a drill and power it out? Nick Link to comment Share on other sites More sharing options...
kurtm Posted January 14, 2009 Share Posted January 14, 2009 (edited) A big flash DOESN'T mean it is bad, it just means there is still pleanty of unburnt fuel exiting the barrel. Your Rolling Thunder comp gives it a place to deposite a lot of the carbon from all this now burning fuel. Matter of fact some of the coolest burning powders ( read lots of inhibitors like graphite/ carbon/ calcium carbinate ) have the brightest flash. the PMC made in South Africa is a bit on the dirty side ( lots of calcium carbinate ), which is giving you pleanty of deposities, but it isn't hurting a thing. Come to think of it the only gas tube I ever saw resticted was with S.A. PMC. but this was after thousands and thousands of rounds. KurtM Edited January 14, 2009 by kurtm Link to comment Share on other sites More sharing options...
George Posted January 14, 2009 Share Posted January 14, 2009 Looks a bit like lead from the open base of the FMJ. Ian makes a good point. Now that I think about it some, it does kinda' resemble what I get around the baffle holes on my AR's when I shoot 55gr loaded with the Hornady bulk boat tail FMJ with exposed lead base. My powder choice leaves a different coloring, but the globules do look like the lead left from those Hornady's. If they are soft enough to scrape away with a small blade, then it may just be lead. Pull a bullet from one of these rounds and see what the bullet base is like, I am thinking it's exposed lead. Link to comment Share on other sites More sharing options...
Brian Payne Posted January 14, 2009 Share Posted January 14, 2009 Not meaning to take away from the debate, but a quick question. If you have this on your comp, does it hurt anything to just keep shooting it, or is it a must that it be removed? Just curious. Link to comment Share on other sites More sharing options...
Chris Posted January 14, 2009 Share Posted January 14, 2009 My comp is full of carbon, but it doesn't look like that. Mine just has a lot of black crud built up in it. Link to comment Share on other sites More sharing options...
bigbrowndog Posted January 14, 2009 Share Posted January 14, 2009 Brian, I usually clean mine in the off season, just to open up the expansion chamber at the muzzle, I go ahead and soak the comp in Chemtool and it takes care of everything at once. you can scrape through the ports with a knife blade if it concerns you. Trapr Link to comment Share on other sites More sharing options...
GentlemanJim Posted January 14, 2009 Share Posted January 14, 2009 Erosion is just a normal fact of life in a rifle comp. I have JP comps with quite a bit of erosion showing. shorter barrels seem to cause them to wear faster..may be the higher velocity of hot gas at somewhat higher pressures. some powders may also make a difference. Just as the crown on a barrel can cause a POI change, so too can the entry and exit of a comp port The gas is expanding at a velocity higher than the bullet speed...so it passes the bullet in flight The way the gas interacts with the port...has an influence on the bullet. A crisp uniform and symetrical opening will perturb the bullet to a much lesser degree than a ragged hole. When and IF you start to lose accuracy...thats when it becomes an issue. Jim Link to comment Share on other sites More sharing options...
Shay1911 Posted January 14, 2009 Author Share Posted January 14, 2009 Erosion is just a normal fact of life in a rifle comp.I have JP comps with quite a bit of erosion showing. shorter barrels seem to cause them to wear faster..may be the higher velocity of hot gas at somewhat higher pressures. some powders may also make a difference. Just as the crown on a barrel can cause a POI change, so too can the entry and exit of a comp port The gas is expanding at a velocity higher than the bullet speed...so it passes the bullet in flight The way the gas interacts with the port...has an influence on the bullet. A crisp uniform and symetrical opening will perturb the bullet to a much lesser degree than a ragged hole. When and IF you start to lose accuracy...thats when it becomes an issue. Jim Should I be worried about the expansion chamber where I cant see what is going on? This comp has an expansion chamber before the comp port. I cleaned up the tops of the "bumps" with some sand paper and it is now a funnel, not a straight wall port. I only knocked the tops of the bumps off, didnt sand more than that, but can feel a funnel on first port AND second port. It is really not a big deal. I will stop shooting that ammo and replace the comp every once in a while, when I noticed a drop in performance. I think this PMC ammo was made in Korea. Link to comment Share on other sites More sharing options...
GentlemanJim Posted January 14, 2009 Share Posted January 14, 2009 Unless you see a real problem with accuracy...dont worry about it. sooner or later they all end up with wear, I saw a comp that the first port was about the size of a dime The owner never even noticed it Jim Link to comment Share on other sites More sharing options...
Middle Man Posted January 14, 2009 Share Posted January 14, 2009 FYI on PMC mfg# 223A, it's the same spec ammo as Lake City XM193. In fact, when ATK was having a difficult time keeping up with orders of XM193 they called up Poongsan (PMC) in South Korea and bought a few containers. Link to comment Share on other sites More sharing options...
jobob Posted January 15, 2009 Share Posted January 15, 2009 This all got me thinking and I looked inside a Miculek comp that's been on a couple of rifles and has a few K rounds through it. Almost all were either Federal 55 gr. American Eagle, or Black Hills 55 gr., no PMC. I'm seeing quite a lot of erosion on the back facing surfaces of the baffles. All show a funnel or dish shape around the hole in this area, where the metal of the comp has actually been eroded away. I guess, when you think about it, that it's pretty logical that this should happen. That surface gets slammed with hot high pressure gasses and unburned powder particles with each shot. Darn, I'd say that at this rate of erosion the comp only has about 20,000 rounds left in it! Link to comment Share on other sites More sharing options...
lmccrock Posted January 15, 2009 Share Posted January 15, 2009 FYI on PMC mfg# 223A, it's the same spec ammo as Lake City XM193. In fact, when ATK was having a difficult time keeping up with orders of XM193 they called up Poongsan (PMC) in South Korea and bought a few containers. Not sure where that information came from, but the current 223A is slower than M193. Chrono'ed by me and the Multigun Nationals, PMC Bronze "223A 55grs. FMJ-BT" runs about 3030 fps, which is slower than M193. Not bad for 223 but slow for M193. Lee Link to comment Share on other sites More sharing options...
Triggerbender Posted January 15, 2009 Share Posted January 15, 2009 Been shooting PMC for years when it was cheaper, the stuff from Korea and R.S.A. all my rifles like it, wish I had more. Like Imccrock said not up to nato spec. I do recall however hearing about some of the first PMC out years ago in the Camo boxes that was to nato spec, I never managed to get my hands on any though. Link to comment Share on other sites More sharing options...
dstroyed Posted March 9, 2009 Share Posted March 9, 2009 This is in no way a complaint against the manufacturer of the comp. I do think its the ammo.Is this normal? Should I be expecting this? I am sure about the round count. Has anyone figured out what this is? Build up or erosion? I have a comp that looks just the same. Did you lose accuracy with your comp like this? My Comp has less than 300 rounds, Fed military and Wolf. A week ago we were hitting steel plates at 400 yards and now bullets are tumbling at 25 yards. Link to comment Share on other sites More sharing options...
Shay1911 Posted March 9, 2009 Author Share Posted March 9, 2009 This is in no way a complaint against the manufacturer of the comp. I do think its the ammo.Is this normal? Should I be expecting this? I am sure about the round count. Has anyone figured out what this is? Build up or erosion? I have a comp that looks just the same. Did you lose accuracy with your comp like this? My Comp has less than 300 rounds, Fed military and Wolf. A week ago we were hitting steel plates at 400 yards and now bullets are tumbling at 25 yards. The comp works great, I really like it. It is definitely erosion in the first and second chamber. You can actually feel the funnel shape. I have decided to not worry about it, frankly. I love the comp, it works great and I don't mind buying another one when I wear this one out. So far, my accuracy is not affected at all. I really have no clue why yours has changed. I did take a dremel to it and cleaned up the build up, knocked off the tops. I guess the speed of the gasses vaporizes metal and forms "tumors" on top of the metal while eroding it. I just knocked them down. I suggest you clean yours first and see if they are still tumbling. Link to comment Share on other sites More sharing options...
dstroyed Posted March 9, 2009 Share Posted March 9, 2009 I'll have to try cleaning the "tumors" off with a dremel. - thanks Link to comment Share on other sites More sharing options...
bagdrag Posted June 28, 2011 Share Posted June 28, 2011 (edited) Just wondering if the pitting discussed in this thread is common with compensators. I have a JP with about 1000 rounds (a mix of Prvi Partizan 75gr Match and Federal XM193) through it that has the same pitting in the comp. What type of comp wear are the rest of you experiencing when do you replace your comp? Edited June 28, 2011 by bagdrag Link to comment Share on other sites More sharing options...
pjb45 Posted June 28, 2011 Share Posted June 28, 2011 I had a JP rifle and comp in my possession recently. The comp looked exactly like your pictures. I soaked and scraped the residue off the comp. It came out like new when I finished. If you are gentle you can use dental scrapers. I took the barrel off and just soaked the comp in barrel cleaning stuff. After seven or eight iterations of soaking and scraping the thing was good to go. Try some Nano 386 after you clean the comp. It does seem to help a lot. Link to comment Share on other sites More sharing options...
bagdrag Posted June 28, 2011 Share Posted June 28, 2011 I had a JP rifle and comp in my possession recently. The comp looked exactly like your pictures. I soaked and scraped the residue off the comp. It came out like new when I finished. If you are gentle you can use dental scrapers. I took the barrel off and just soaked the comp in barrel cleaning stuff. After seven or eight iterations of soaking and scraping the thing was good to go. Try some Nano 386 after you clean the comp. It does seem to help a lot. I'll try cleaning it again but it really seems like the metal has been altered. There even feels like a part of the metal has been warped. I may polish with a dremel to smooth it out. I'm not going to worry about it too much as long as the accuracy is not affected. Link to comment Share on other sites More sharing options...
mpeltier Posted June 29, 2011 Share Posted June 29, 2011 Just wondering if the pitting discussed in this thread is common with compensators. I have a JP with about 1000 rounds (a mix of Prvi Partizan 75gr Match and Federal XM193) through it that has the same pitting in the comp. What type of comp wear are the rest of you experiencing when do you replace your comp? Yes it is normal. I usually leave it alone. I like to leave the carbon deposits alone. They may protect the metal underneath cause I have not worn one out yet. Link to comment Share on other sites More sharing options...
Shadowrider Posted June 29, 2011 Share Posted June 29, 2011 Got a buddy that pitted one of those out in about 500 rounds. But he was running it on a 10.5" SBR. I wonder how much one would cost if it were made out of Inconel? Nothing will stop the pitting completely, but that would sure slow it down. Link to comment Share on other sites More sharing options...
bagdrag Posted June 29, 2011 Share Posted June 29, 2011 Just wondering if the pitting discussed in this thread is common with compensators. I have a JP with about 1000 rounds (a mix of Prvi Partizan 75gr Match and Federal XM193) through it that has the same pitting in the comp. What type of comp wear are the rest of you experiencing when do you replace your comp? Yes it is normal. I usually leave it alone. I like to leave the carbon deposits alone. They may protect the metal underneath cause I have not worn one out yet. Got a buddy that pitted one of those out in about 500 rounds. But he was running it on a 10.5" SBR. I wonder how much one would cost if it were made out of Inconel? Nothing will stop the pitting completely, but that would sure slow it down. Thanks for the replies. I will test it this weekend to make sure my accuracy has not been affected. Link to comment Share on other sites More sharing options...
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