new chassis significant drop changes

Kyle87

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Oct 18, 2011
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115
hey guys i got a new mcrees chassis on my sendero. this is the second time out with it and i am having alot of problem with my trusted drop chart from the factory h&s precision. i zeroed it and it is shooting right at a half minutes at 100. when i stretch it out is when i get in trouble. my old drop chart was 7 moa at 500. i went out the first time with the chassis and had it seemingly dialed in that day at 6.5moa at 500. tonight we went out and i dialed 6.5 and i was high, came down a half, high again, long story short it settled in at 5moa. load is winchester brass 162gr amax cci 250 primer and 70.5gr retumbo. is this a rear bag problem? it seems that i have a hard time settling in with the new chassis and the small area in the rear for the bag. any advice would be great thanks!
 

FearNoWind

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Couple of ideas. It's pretty easy to get a bind when mounting an action to an aluminum chassis. Careful alignment and torquing sequence can be critical. I assume the stock came with torque sequence instructions? If that's all in order, take a close look at scope mountings for alignment and torque.
Without some data on the style/type of rear bag you're using it's difficult to factor that into the equation. But vertical stringing can be attributed to rear bag issues so it's a possibility. Shoulder pressure, loading or not loading the bipod, all could be factors in what you describe.
 

BergerBoy

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I'm NOT a patriot... I am a U.S. Constitutionalist
I agree with FearNoWind. You probably have something that is not setting in just right. I had a similar issue with my .308 when I changed out stocks. It turned out that my front action screw/bolt had not set in all the way through the stock even though it was tight. Check your recoil lug, it may not be resting correctly in it's slot.
It defiantly sounds like something is moving but it's a lil storage that your at .5 minute at 100 yds and it opens up on you down range.
Good luck
 

WildRose

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Feb 3, 2011
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N. Texas and S. Africa
hey guys i got a new mcrees chassis on my sendero. this is the second time out with it and i am having alot of problem with my trusted drop chart from the factory h&s precision. i zeroed it and it is shooting right at a half minutes at 100. when i stretch it out is when i get in trouble. my old drop chart was 7 moa at 500. i went out the first time with the chassis and had it seemingly dialed in that day at 6.5moa at 500. tonight we went out and i dialed 6.5 and i was high, came down a half, high again, long story short it settled in at 5moa. load is winchester brass 162gr amax cci 250 primer and 70.5gr retumbo. is this a rear bag problem? it seems that i have a hard time settling in with the new chassis and the small area in the rear for the bag. any advice would be great thanks!
What is the difference in temperatures from today and the last two outings? Retumbo is notoriously temperature sensitive so that may well be the source of your problem if there's a significant difference in temps.

You may also have an issue simply due to the change of stock causing you mount and drive it differently than your prior stock.

Measure your comb height with both and see how much difference there is.
 

Kyle87

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Oct 18, 2011
Messages
115
Thanks for the replies guys the temp difference was about 20 degrees. The chassis did come with torque specs but didn't have access to a torque wrench when I put it all together. I ust to struggle with 100 yard groups and now that I got this chassis they have tightened up and everything else has went down hill. I'm thinking it is me and like you said the way I'm driving the whole system and maybe my lack of time with it that it the problem. I tried two different bags last time a leather one with ears that I struggled to get to fit right and just a basic sock with corn.
 

Canadian Bushman

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Jan 24, 2012
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1,814
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Houston, Texas
What is the difference in temperatures from today and the last two outings? Retumbo is notoriously temperature sensitive so that may well be the source of your problem if there's a significant difference in temps.

You may also have an issue simply due to the change of stock causing you mount and drive it differently than your prior stock.

Measure your comb height with both and see how much difference there is.

These were my first two thoughts as well.

Difference in cheek weld and shoulder pressure as well as weight on the bag can show up as variance in elevation.
 

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