RAW velocity loss

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tsp3355

Member
May 13, 2015
269
4
Colorado, United States
Looking for some advice. I have a RAW HM1000 25 cal that was set up by Martin for maximum accuracy at 835 fps using 25 gr JSBs. It has always been an absolute tack driver. I was at the indoor shooting range last week and had just shot a 3/4" group at a hundred yards which is a little better than what I usually see. When I'm doing my part it's normally between just under an inch to and inch and half shooting unsorted ammo right out of the tin with an occasional flyer. When I went to shoot the next group my POI dropped about 3 inches and the group opened up to about 3 inches as well. Same thing with the next two groups. I had been shooting for a while and hadn't cleaned the barrel in a while, so I figured the barrel was probably dirty and headed home. I cleaned the barrel and decided to check the velocity. I topped off the bottle to make sure it wasn't off the reg and sure enough, the velocity had dropped almost 20 fps, and even with the HST maxed out, I couldn't get it any higher than 824 fps. I haven't had a chance to get back to the range to test the accuracy, but I'm betting the POI is still going to be low based on the lower velocity.

Has anyone else had this issue with a RAW? Mine is right about 2 years old, and has probably no more than 7 or 8 tins of pellets through the tube. Any advice greatly appreciated!

Thank you!

TracyP
 
I don't believe the shroud is clipping. I haven't been back to the range to test it again since I cleaned the barrel and checked the velocity. I may be able to do that this weekend. I also want to run a couple of full 60 shot strings over the chrony and see what I get. Just seems really strange to me that it was shooting perfectly for the first hour plus and then all of a sudden the POI drops. Before moving to 100 yards I had shot a half a dozen groups each at 50 and 75 yards all were sub MOA and then another 6 groups at 100 all under an inch and a half with a couple under and inch and then the next group the POI drops. I didn't actually measure what the POI drop was, but it was definitely more than 2 inches.
 
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That happened to me on my TM1000. Martin advised me to take the hammer out and clean it. When I removed it, it was greasy from some lubrication residue from the trigger, I think. Anyway, I cleaned it and applies a very light coat of a low viscosity oil (I emphasize light) and re-assembled. Oh, and don't forget to clean the inside of the receiver too. The problem was gone. When you remove the hammer, be sure to note how all the internal parts fit together. Picture attached.
1523030206_9989068915ac798beebeea2.91098425_TM Hammer Stack.jpg
 
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