Double digit ES

[Wile E Coyote]

Some good points taken from the posts. thanks

A few days ago, I picked up a couple different boxes of LR primers (100); Remington 9 1/2 and Winchester 8 1/2. Didn't see Wolf brand. I'm going to load 5 rounds with each primer and keep all else the same. This weekend I'll have a chance to shoot them at 300 to 400+yds and we'll find out if either group better on paper. If one shows promise, I'll reload more and run them through the chrono.

Another combo I plan on trying is the milder primers with some H1000 I have. H1000 worked very well in a 300WM I had. (shoulda' kept that rifle but I traded it for the 7RM I'm working with now)

I don't expect any pressure issues but I'll watch for them of course. If anything, I wouldn't be surprised if one or more didn't fire because the primer isn't hot enough.

On another point mentioned is the chronograph. I recently aquired a CED M2 chrono and have found it to work very well when used as directed. (as most things do) The couple of occasions when I had suspect numbers, I was able to resolve it by reading the book and following the directions. Accuracy of the unit was confirmed when we set up 2 M2s back to back. They recorded nearly identical numbers for several different rounds tested that day; from 22lr to a 338 edge. After that, I'm confident of the numbers recorded with the M2 provided I use it properly.

Thanks again

 

[Bart B]

I'm going to load 5 rounds with each primer and keep all else the same. . . If one shows promise, I'll reload more and run them through the chrono.

5 shot groups are marginal for representing what will happen all the time. I'd shoot at least 10 and 15 to 20 is better. Especially if you hold onto the rifle when it's fired.

Group Size Analysis

'Course if your barrel bends as it heats up opening up the group, then let it cool down between shots.

 

[runshort]

Only have a moment here to reply to comments thus far... in no particular order. Thanks for the input all

Regarding bushing selection: when I mention .308" or .307" bushing, those are the two I seem to use most often. I'm not set on any particular one and I could have worded that a little better. my fault. One thing I do differently and failed to mention is AFTER neck sizing. I measure the ID of the finished neck with a shopmade plug. After struggling to accurately measure the ID of the cases, a machinest friend made up a set of 'plugs' turned to .0005" increments. She made 6 for me for the .284 including .2835, .283, .2825, .282, and .2815. Fitting the tightest one without forcing is how I determine a .002" or a .0015" neck tension. Don't know if this is correct but this is how I do it.

Regarding H1000: It may be on the horizon but I have 5 or 6 pounds of Retumbo yet to burn up.

As for annealing: It's on the radar but resource$ are not there at the moment.

and lastly, the muzzle blast affecting the chrono result: I made a plywood blast shield that is placed between the gun and the chrono. I set the chrono at the max distance the cables will allow and set the blast shield about mid way. the plywood is 30" wide by 40" tall (I had the piece cut to that dimension already) with a 3" wide x 8" tall hold cut in the center. The panel is canted away from the gun at about a 45 deg. angle with 2x3 legs to support it. I learned this trick with my old Shooting chrony Beta Master chrony. That unit was actually accurate BUT very succeptable to outside influences.

Again, thanks

Wile
I'm curious about your blast shield that you place between rifle and chrono.
How much difference do you see in between having the shield in place as oppposed to not having one.
That sounds like a really good idea. I always place my chrono at 15' from the bench just out of habit I guess, but have noticed the muzzle blast from magnum rifles tend to make the screens move somewhat and have wondered how much that affects ES and SD as well as velocity that you see on the chrono.

 

[Wile E Coyote]

Runshort,
The 'blastshield' makes a tremendous difference. I don't shoot through the chrono without it anymore. The trick to using it I find is to place it equi-distant between the muzzle and the chrono. If it is too close to the muzzle, the blast simply shoots through the hole. When the shield is close to the chrono I also get errant readings and/or errors though less frequently. Why I get them in this setup is something I haven't figured out yet. When I say errors, i'm referring to a situation such as when shooting my 7RM, I expect a number around 3025 to 3050FPS. Once in a while a shot will record a significantly lower velocity. That error, I'm assuming, is the pressure wave of the muzzle blast since the recoil is still the same.

By chance one day, I set things up spaced out equally and shot 50 rounds of 22LR, 7RM, 300WM and a S&W500 through the chrono without a single error. Since then, Ive only had a couple or shots the recorded errors. All of those errors occured when my shot and a shot on an ajacent line happened together. The 22LR is somewhat of a benchmark for me. I know it will be running just over 1200FPS and it gets the kids into the game too.

I also have another chrono, a Shooting Chrony Beta M that I have given up on. The only way I could get that one to record reasonably consistantly was to put it in a box and shoot through a hole in the box. Somewhere here on LRH is a couple of pics of that setup. I could find them but I don't know how to link to them.

Bart,
I agree that 5 rounds is insufficient for a thorough analysis. What I do is shoot 3 from a lot of 5. If they group well, I'll send the other 2. Then I'll compare the 5 shot groups, pick the best of the best and do more work-up on that one load. All i'm doing is trying to keep the mileage down on the barrel by only firing rounds showing promise.

Pete