Another typical weekend here at Gun Lab. As with all weekends a certain amount of maintenance has to be completed. Saturday morning was spent doing some design work in solid works for a new piece of equipment that we are building to make fluted barrel chambers (more on that a little later in the week). I rebuild a friends AR-15. In this case it was a barrel change with new gas block and a very nicely design front hand guard and barrel nut. A write up of those components will be shortly as well. I really like the fit and feel of this equipment. Enough in fact that I am ordering on for myself. After the rebuild I did a test fire of the weapon in my test firing tube. This is a basic testing tube for function and reliability. I made the tube out a section of heavy wall steel pipe then filled it with sand and to reduce the noise level I added a series of small tires in the inlet and then caped it with a rubber end piece. It works well and reduces the noise level so there is no problem with the neighbors.
There is however one small glitch. That is unburnt powder will build up in the tires. This can cause a bit of excitement at about ever 50 or 60 round when all that powder ignites. This is a video that was taken while I was test firing the AR.
I will post this video as soon as possible. The video that was taken was done on a phone and when sent to me was of such low quality that it is not usable. Post was made off a phone video.
I installed the air dryer for the shop air system. This is it as delivered.
And as it now sets hooked up.
It was a basic hook up, just needed the hoses made up and power run to it. A quick shot of the plumbing.
The last task completed this weekend was finally finishing the lights and power in the fab shop. A couple of pictures of that.
A couple of pictures at night with the lights on to give you an idea of what it looks like.
Everyone say that it is to be used as a beacon for the international space station when all the lights are on.
Hope you enjoyed the updates.
No easy answer to your test tube autoignition situation. Smokeless powder is essentially self oxidizing (actually nitriding), so you really have to clear out the unburned powder.
Guys around here who use scrap tires to suppress gunfire noise cut the tires all the way across radially in one location each and orient the cut at the bottom with a several inch opening gap. Then they position a collection pan with angle iron baffles below (angle up, at the top of the collection pan, with small spaces between the angle ‘leg’ ends) to collect the unburned powder.
You have to chamfer the tire cuts so the powder will slide out of the tires at the gap, and then drop into the pan. The tires have to be fixed so they won’t rotate, but this can be done by drilling them and using bolts or lag screws to hold them in place, with the bottom gap open. The catch pan can then be slid out and dumped. The angle iron baffles also seem to retard ignition of the accumulated powder in the pan.
The other alternative is an ‘L’ shaped suction wand on an explosion proof vacuum cleaner. Very expensive.
Interesting and thanks for the info. I will look into making changes to the test fire tube.
One quick remedy that could(should)work would be to spray or mist some water into the end of the tube. That should wet the build up of unburnt powder enough to prevent it from igniting when you fire a round into the tube.
That’s interesting! I have similar with an 8″ pipe partially full of sand but am using a dense foam rubber piece that plugs the end but is slit so the barrel can go thru. I shot a .223 in it and the pressure blows the plug out. Thinking I need to let it vent out the rear more than that plug lets it.
Pete
Mac The water Idea will not hold up. A lot of powder is made in a water solution then dried before use. A friend of mine was an expert witness in a court case. The small commercial reloader was injured when he discarded a cigarette while mowing grass in an area he had used for many years 30+ as his dump where he spread his used or unusable powder. The man was burned in a flash fire. He sued the powder makers. He thought that years of rain and snow had made it safe. My friend brought in many older to new reloading manuals. They all said the proper was to dispose of small quantity’s of unwanted powder is to place it in a pile or concrete. and light a fuse or powder train so you can be away from pile when it burns. The man was found to be the cause of his own accident.