ar15 for F-TR

[sbetts]

well i believe this is only my second post but here it goes. I originally got my ar15 for service rifle competition but due to physical limitations, using the sling in prone to support the rifles weight causes me pain. Prone with a bipod or rest is no problem for me

so i picked up a nikon monarch 5 - 20x scope to test loads and have some fun. The barrel is a WH merchant 20 inch stainless 1:8 twist with a very long chamber. harris bipod and some no name rear bag.

my main question is what is an acceptable short range group size to be some what competitive in a 600 yd F-TR match? I understand there are alot more variables in play than the 100yd test, but it would be nice to have an idea of when im getting reasonable results. And if you have any comments or ideas that will help me out in the game of small bullets vs the .308.

I just worked up a load for berger 80vld today .010 off the lands various loads and did ok. The group measured with on target shows .368 inches max spread and .152 average center to center. tested at 100 yds. I will start adjusting seating depth next and see if I cant shrink that down a bit. also i believe the vertical stringing was a slightly hot barrel. there was someone waiting in line for the no wind tunnel hurrying me along. Once i sort the oal i will head to the 600 yard range and try it out.

thanks for your input
Scott Betts

 

[Steve Blair]

The 600 yard F-Class X ring is 3" and the 10 ring is 6". If your rifle will consistently group ½ MOA, you can be competitive at club level. Reasonable loads from a 20" barrel will work fine in Mid-Range shoots. 1000 yards is beyond that combination's capability.

 

[xdshooter]

HI, here is a load given to me by a sierra engineer works great in bushamaster dcm i think you will like it, 77 grain bullets and I use 23.6 gr. of Tac with a Win. Small rifle primer and I use a Lee factory crimp die and just kiss a slight amount of crimp on it. Works great with my single shot mag. Good Luck

 

[Keith Glasscock]

100 yard groups are hard to read for this purpose- period! I do see some vertical in yours - that is not a good sign *if* the vertical is caused by the load. As I am sure you have heard before, 3 shot groups do not work out statistically to mean much.

I also noted your comment about barrel heating. I have yet to see a barrel come off the line at an F-class match that wasn't hot. Heating is part of the game. We all just learn the quirks of our rifles as they heat up. For instance, I have a friend that always have a cold bore shot of 7 at 12 o'clock. The second shot is almost always an x or 10. My rifle wanders up and down about .25 moa during a string.

I would suggest you do 2 things. First, find a 300 yard or greater range and shoot groups on it. Don't worry about windage as much as vertical. The vertical is what kills you in F/TR. Second, before commiting to a load for a match at 600, I would shoot at least a 10 shot group at 300. If the vertical is greater than 2" at 300, the load is marginal for keeping it in the 10 ring at 600. My best loads shoot nice straight horizontal lines in windy conditions at 300. The others - they produce 1.5-2" of vertical at 300 and are a known limiting factor at 600 and beyond. That doesn't mean they can't shoot great scores - I have several 199's at 600 with "marginal" loads - they just make it harder.

Whether an AR can shoot good scores at 600 - I've seen it done with amazing regularity by one of our league shooters.

In the end, the "F" in f-class means fun to all of us. Go have some fun!

 

[sbetts]

very good information busdriver. the main reason for the 3 shot 100 yard groups was a completely new load for my rifle i worked up from my quick load min to a max to get an idea of group and mainly pressures. now i have some idea of my pressures i feel confident in loading up more with a few of the loads that show some promise.
what would you suggest as the number of rounds per load to try? and maybe test them with the ladder method? once that is complete try changing seating depths? and i will get out to our 600yd max range to see what happens

thanks
Scott

 

[Keith Glasscock]

I'm by no means an expert on the subject, but I'll give you the little bit I've learned.

I use 3 shot groups while searching for possible nodes. After I identify a possible node area, I do a 5 shot group (or groups if I'm testing more than one powder charge or depth). After I've identified a possible good load, I go to the 10 shot group. From a statistical standpoint, it really takes about 15 shots of a given load to tell what the performance really looks like. You can do that during your first match.

I wouldn't be afraid to take your 100 yard load to 600 and give it a go.

Do make certain to give yourself some room in the pressures for changes that will occur when you change seating depth and/or temperatures.