How many rounds before groups open up with the 17HMR?

[DalesCarpentry]

I am new to the 17 HMR. I took mine out last weekend and it shot real well. I could cover most 3 shot groups at 100 yards with a dime. Then it droped off real quick like. My sweet tight little groups were over an inch. At that point I thought I put about 70 or 80 rounds down the bore. After doing a count it turns out I shot 51 rounds. So how many round do you fire before your groups open up? I have cleaned the barrel well and have not made it back to the range yet. I think with this little bore I may have to a cleaning rod with me to the range. Dale

[GregP42]

Dale,

After I shot mine in, which took about 500 rounds or so, I can normally shoot about 200 rounds before it opens up to inch size groups, and it will stay at that size for I don't know how long. I have shot 800 rounds without cleaning and it was still running an inch at 100 yards.

Greg

[Ladobe]

I'm old school in that I don't clean rimfires unless I absolutely have to, and that includes my six 17 rimfires.   Way more bores are ruined from over cleaning and improper cleaning than shooting, and that will hold even more true with the 17's.   That said, every barrel is going to be different Dale, so results are going to vary.   But I can tell you what I did that made a huge difference in mine.  I hand lap my barrels before they every see the first shot fired in them.    No break in and very long shot strings is the benefit.   However, you can't get rowdy with these little bores lapping them... or cleaning them for that matter... they are very easy to damage.   It might be better to have it lapped by a competent smith on these small bores if you don't have long experience doing it yourself.   FWIW

[DalesCarpentry]

I'm old school in that I don't clean rimfires unless I absolutely have to, and that includes my six 17 rimfires.   Way more bores are ruined from over cleaning and improper cleaning than shooting, and that will hold even more true with the 17's.   That said, every barrel is going to be different Dale, so results are going to vary.   But I can tell you what I did that made a huge difference in mine.  I hand lap my barrels before they every see the first shot fired in them.    No break in and very long shot strings is the benefit.   However, you can't get rowdy with these little bores lapping them... or cleaning them for that matter... they are very easy to damage.   It might be better to have it lapped by a competent smith on these small bores if you don't have long experience doing it yourself.   FWIW

I have used Flitz metal polish on many bores in the past. As a matter of fact I have polished every bore of every rifle I have owned in the past 5 or 6 years before I even fired a shot through them. The reason being less break in time. I have to say I have had some real shooters too. I do not know if it is because of me polishing the bore or not. The reason I did not do it with this 917 Marlin is because of the micro groving. I am afraid I would do more harm than good on it. I took some pictures of my new toy tonight and here they are. I put a BSA Sweet 17 on top of it. It is a 6x18x40 with the side focus. It also compensates for 17 and 20 grain bullets. I have not had a chance to try this scope out as they advertise it but I will. Dale

[DalesCarpentry]

Here are a couple more. Dale