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tri70 12-25-2012 11:14 AM

Shimming the gas block....
Similar to bedding the gas block, I have not modded any of my minis in a while and got to thinking about a way to mess with the gas block and try making a piece of lead into a gasket to work like a shim for bedding. I found some fishing bullet shape slip sinkers and smashed with a hammer to desired shape. I knew I needed it to be thin enough to get the stock on but thick enough to make a difference. I got it smashed and set into place then put together, I could feel the stock was tighter and tapped the gas block lightly to seat the lead.
I got out for a little bit yesterday and fired a few shots. My poi had changed, the gun was shooting high about 6 inches, I was shooting from a clean bore. I was using a stock 5 rd mag and will try 20 rd mag this weekend. I shot 4 groups and could see right away the lead and stock were still settling in to get mated together. No pictures at this time, will get some this weekend.

Group 1 was high 6" and 1 shot flier low and left 4" away from rest (bedded action) and the other 4 shots 3" group.

Group 2 was done after scope adjust, 1 shot was low and left again but only 2" away from the other 4 shots the were centering left about 2".

Group 3 was better with 1 shot only 1" low and slightly left of the other shots, I did notice 3 shot group almost touching and 1 and 5 shots were about 1" away from the 3 shots. The group is about 3" with all 5 shots, getting tighter with each group.

Group 4 was a pleasant surprise, all 5 shots grouped 1" high like I wanted and a nice 1 1/2" pattern. I will have to try some more to make sure it was not a fluke and everything is settled in.

One of the reasons for choosing lead, it's easy to work with and will dampen unwanted harmonics.

trip 01-06-2013 03:45 AM

What does shimming the gas block do?

tri70 01-06-2013 11:18 AM

It acts like bedding, add material to the stock and gas block mating area to give a solid lock up but no binding. I didn't shoot enough this weekend to tell if it's what I want. I was sick last weekend and didn't shoot at all. My first shots were 6" high, the next group looked pretty good around 2" at 100 yds. Need more testing, the reason for shimming was to see if the gun will shoot better.

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