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Things learned in the test tunnel

Thanks Gaintwist. I had a great time and highly recommend the CMP matches at Camp Perry for those interested in that type of shooting.

My rifle is something we recently built in our shop and of course put all of our newfound knowledge in.

I chose a PQP 2500X action for the build. The day before it arrived I asked Jerry Stiller if there was enough tang to allow me to mount an Anschutz trigger (I use these on all of my prone guns). He said he didn't think so. Well, things came together well and I sent him a picture about 7 pm the next evening of his action with the Anschutz trigger mounted to it. It has worked marvelously.

The stock is a Tec-Hro. I've used these on a couple of my centerfire guns as well as for customer builds. They use a big inelt and adapter blocks to hold a wide variety of actions. I chose to start with the adapter for the round Anschutz 54 family. This particular block allowed me to put the action quite far back in the stock. This makes the loading port easier to reach in prone.

For the barrel I was able to grab a Muellerworks 1-16 twist 8 groove, 26" long. It's been a shooter right from the gate. The chamber is the old standby Winchester 52D. It shot a wide variety of ammo well. In testing I found a lot of Center X and a lot of Tenex that both shot very well. As I tested these 2 lots I couldn't really determine a winner. I chose to shoot the Tenex at this match. It happens that another of my guns shoots this lot very well so I can share the ammo between the two guns.

The tuner is an Uptagrafft Tuner Tube, 12" long. We use these to extend the front sight out from the muzzle. For my aging eyes it makes the front sight a little sharper. The ability to tune is a big plus.

Accuracy at 50M averaged just over 13mm outside ot outside. While we have seen some smaller groups I have been very pleased with the consistency of the accuracy. Across multiple groups it didn't vary much.

As it happens I shot the inital lot testing with the tuner set at #500 which is where it came out of the box. Let's call this a random setting. The next day I realized I had a good testing opportunity. I shot the rifle with the whole tube/tuner removed. The rifle selected the same lots of ammo, but the group sizes were all larger by about 11%. The following day I reinstalled the tuner and tested it out. Compared to the random setting, I improved the accuracy by 3-4% I think it is. I ended up with the tuner set to #100, so it wasn't like the random setting ended up being close to the optimal.

Concerning the tuner test, I shot it at setting 0, 50, 100, etc on to 500. The rifle shot its best at 50 and 100. I split hairs between thsoe two settings but franly couldn't see any significant difference across a number of groups. All groups were 10 shots each, and I shot more than 1 group at any promising looking setting. In the end, I set it to 100 and started working on position and wind reading and those important things. I'm not saying this is the best way to tune or anything, just reporting what I did.
 
Thanks Gaintwist. I had a great time and highly recommend the CMP matches at Camp Perry for those interested in that type of shooting.

My rifle is something we recently built in our shop and of course put all of our newfound knowledge in.

I chose a PQP 2500X action for the build. The day before it arrived I asked Jerry Stiller if there was enough tang to allow me to mount an Anschutz trigger (I use these on all of my prone guns). He said he didn't think so. Well, things came together well and I sent him a picture about 7 pm the next evening of his action with the Anschutz trigger mounted to it. It has worked marvelously.

The stock is a Tec-Hro. I've used these on a couple of my centerfire guns as well as for customer builds. They use a big inelt and adapter blocks to hold a wide variety of actions. I chose to start with the adapter for the round Anschutz 54 family. This particular block allowed me to put the action quite far back in the stock. This makes the loading port easier to reach in prone.

For the barrel I was able to grab a Muellerworks 1-16 twist 8 groove, 26" long. It's been a shooter right from the gate. The chamber is the old standby Winchester 52D. It shot a wide variety of ammo well. In testing I found a lot of Center X and a lot of Tenex that both shot very well. As I tested these 2 lots I couldn't really determine a winner. I chose to shoot the Tenex at this match. It happens that another of my guns shoots this lot very well so I can share the ammo between the two guns.

The tuner is an Uptagrafft Tuner Tube, 12" long. We use these to extend the front sight out from the muzzle. For my aging eyes it makes the front sight a little sharper. The ability to tune is a big plus.

Accuracy at 50M averaged just over 13mm outside ot outside. While we have seen some smaller groups I have been very pleased with the consistency of the accuracy. Across multiple groups it didn't vary much.

As it happens I shot the inital lot testing with the tuner set at #500 which is where it came out of the box. Let's call this a random setting. The next day I realized I had a good testing opportunity. I shot the rifle with the whole tube/tuner removed. The rifle selected the same lots of ammo, but the group sizes were all larger by about 11%. The following day I reinstalled the tuner and tested it out. Compared to the random setting, I improved the accuracy by 3-4% I think it is. I ended up with the tuner set to #100, so it wasn't like the random setting ended up being close to the optimal.

Concerning the tuner test, I shot it at setting 0, 50, 100, etc on to 500. The rifle shot its best at 50 and 100. I split hairs between thsoe two settings but franly couldn't see any significant difference across a number of groups. All groups were 10 shots each, and I shot more than 1 group at any promising looking setting. In the end, I set it to 100 and started working on position and wind reading and those important things. I'm not saying this is the best way to tune or anything, just reporting what I did.
How did you test the rifle when lot testing off hand or in a jig? congratulations on your Championship win.
if you got 13mm offhand no wonder you won!
Thank you for sharing what you are doing and what you have been seeing. as far as I know this is a first to have a testing facility share rifle build information and corresponding results while both lot testing and tuning.

Also how did you mount the Anschutz trigger I assume a 5018 directly onto the action or did you use an adapter.

Lee
 
Lee, I wish I could say I shot 13mm offhand, but those were the sizes of my test groups.

While at the CMP match, I did have a string of 40 shots where I shot 400-40x in the 50 meter match. This means that every shot touched a .393" X ring. Therefore the group size would have been no larger than .393" + .221" =.614" center to center. This was from prone with a sling and I'm quite happy with it.
 
Lee, I wish I could say I shot 13mm offhand, but those were the sizes of my test groups.

While at the CMP match, I did have a string of 40 shots where I shot 400-40x in the 50 meter match. This means that every shot touched a .393" X ring. Therefore the group size would have been no larger than .393" + .221" =.614" center to center. This was from prone with a sling and I'm quite happy with it.
.393+.221= .614 CTC? I think you meant OTO I believe which is only .103 difference from that 13mm (.511) group offhand! again, great shooting.
to put it in perspective .614=15.595mm I bet you seen some BR rifles at the center which couldn't do much better.
There are so many things which can be tested and hopefully you will have the time to investigate. I would love to know what happens when you start to see ignition issues. such as too weak a hit or too strong. spring rate changes as age sets in. how much does this affect the performance of the ammo and most importantly the accuracy of the rifle.

Lee
 
Lee,

I could have missed the math so please double check me here. Outside group should have been .393" + .221" + .221". Scoring ring plus 2x bullet diameter. This is .835" outside to outside.

Now we subtract 1 bullet diameter to get center to center, so .614" CTC. Let me know if I've missed this. I'm tired this morning!

If so, then yes we've seen some BR rifles shoot bigger than this.
 
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Lee,

I could have missed the math so please double check me here. Outside group should have been .393" + .221" + .221". Scoring ring plus 2x bullet diameter. This is .835" outside to outside.

Now we subtract 1 bullet diameter to get center to center, so .614" CTC. Let me know if I've missed this. I'm tired this morning!

If so, then yes we've seen some BR rifles shoot bigger than this.
Ok, the way you are doing is different from what I was told is done at Lapua which is -5.56 (.221) = CTC so I assumed your +.221 was adding to the .393 CTC to get a .614 OTO doesn't matter still outstanding shooting!

Lee
 
With this question much depends on what is believed.

Some explanations of how tuners do what the do assert that positive compensation explains how tuners work to put rounds of different MVs in a very similar POI. The positive compensation theory says that the tuner does its job by timing the barrel vibrations so that slower rounds exit the muzzle with a higher trajectory than faster rounds. This allows them to have a POI similar to faster rounds.

If positive compensation is correct it would mean that tuners settings work for one distance, not all distances.

For more on positive compensation, see these two well-known explanations.

Of course there's no agreement about how tuners work. Others subscribe to the idea that the tuner works to "stop" the muzzle from moving by tuner adjustments causing a "vibration node" to be at the muzzle. An explanation such as this seems to allow tuners to work at any distance reasonable for .22LR.
So, the data from WGW fits the first theory and not the second one.
 
It's a shame this information sharing thread seems to have faded away. I just got an NPI rifle with a 20" barrel. I do get the Whidden posts which is helping me get some accurate data.
Thank You! John.

ISS
 

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