Deresonator

slimjim · Posted: Wed Mar 16, 2016 5:58 am Post subject: Re: Deresonator

Here are the results of 3-shot groups at different COALs with Hornady's 110 BTHP on top of 28.6gr of AA2200 in resized Hornady brass and 450 CCI primers. The only change between groups was the COAL which was stepped in 0.025" increments: 2.270", 2.295", 2.320", and 2.345" (which was 0.025" off the lands for this rifle). The longer two COALs are achievable with just the magazine modification. Interesting to see that a COAL shorter than 2.295" resulted in improved accuracy. I expected some variation but the average velocity was very consistent between the groups: 2715, 2719, 2697, and 2715 fps respectively.

PaulS · Posted: Wed Mar 16, 2016 7:37 pm Post subject: Re: Deresonator

Slim,
Have you ever taken that resulting great group and tested the load with "x" tenth grains of powder more and less than the "ideal" load to see if your load is still forgiving of a few tenths of a grain of powder?
If so, does the tuning by overall length make the load fussier?

slimjim · Posted: Thu Mar 17, 2016 1:28 am Post subject: Re: Deresonator

Paul, I haven't found tuning with COAL makes the load fussier. However, COAL adjustment is the last step in my load development process. The first step is finding out how forgiving a load is to a few tenths of a grain of powder. I use a single charge weight vs velocity ladder to determine a load's accuracy node. I typically use 0.3 to 0.5 grain increments and record every impact. If I find three that group within 1 moa or 2 that group close in a string of shots where the path of impacts reverse direction, I use the middle charge weight. It doesn't work all the time and you need to know your rifle is 1 moa capable or better. This saves me lots of bullets and I often develop a hunting load in 5 to 8 rounds. COAL from there is just adjusting the exit point of the bullet to be at the node. If a bullet-powder load isn't forgiving to begin with, I haven't found COAL adjustment will make it more forgiving.

Dawgdad · Posted: Thu Mar 17, 2016 9:41 am Post subject: Re: Deresonator

The biggest thing slim said that will waste a lot of bullets for some guys trying to reload..... Can you and your rifle shoot MOA or better.

I see a lot of guys that have horrible bench technique and always blame the load. The worst is when the blind pig finds a nut and shoots a single three shot group and says he has a winner and never shoots that load that well again... but keeps the 3 shot target in his pocket to show how good his rifle shoots.

PaulS · Posted: Thu Mar 17, 2016 10:40 pm Post subject: Re: Deresonator

Dawgdad,
I have seen those folks too. I test any "good" load over several months. I use five shot groups and use an aggregate target with a new overlay for each group. That gives me a pretty good idea of how a load shoots.

slimjim · Posted: Fri Mar 18, 2016 8:07 pm Post subject: Re: Deresonator

As a hunter, its only the first shot, maybe the second, that counts. I keep the same target and shoot 2 shots at the same POI each range session over the year to build confidence in my load and its consistency. I know many like shooting multiple shot groups and I was talked originally taught to shot 5-shot groups but I'm done with 5-shot groups except if its a single shot for 5 consecutive range sessions. That is true accuracy to me.

Dawgdad · Posted: Sat Mar 19, 2016 5:56 am Post subject: Re: Deresonator

For hunting loads, yes, a series of cold bore shots over several range sessions is the proof in the pudding.

For my target shooting I need a load that will shoot sub MOA after 66 rounds are down the pipe shooting the next 20 shots in 20 minutes or less. and also hold up to 10 shots in 60 seconds.

slimjim · Posted: Sat Mar 19, 2016 7:56 am Post subject: Re: Deresonator

Dawgdad wrote:

For my target shooting I need a load that will shoot sub MOA ... and also hold up to 10 shots in 60 seconds.

after 3 shots, my. 270 barrel is too hot to hold.

Dawgdad · Posted: Sun Mar 20, 2016 6:22 am Post subject: Re: Deresonator

Luckily - I do not hold the barrel, :). I have not had it cherry red but it gets warm. Actually, some days in the summer it gets too hot to touch just sitting in the sun... benefits of a heavy target barrel versus a light hunting profile. pretty thermally stable.

chambered221 · Posted: Sun Mar 20, 2016 9:53 am Post subject: Re: Deresonator

Dawgdad wrote:

I see a lot of guys that have horrible bench technique and always blame the load.

They also blame the gun !!!

It should also be noted the technique can change depending upon the type of rifle used.
My 10lb varmint rifle rides the bags pretty good with very little input from me. My Remington Model 7 requires a lot of consistent pressure to control movement and recoil.