lost accuracy with the amax

i have the model 12fv in 223, a few weeks ago the gun was shooting the 75 amax very tight, like under 1/2", also shot the 52 sierra 1410 tight too, all i basically done is added a 3" wide plate to the front of the stock to use a benchrest type front rest, and had the gun apart 5-6 times since, thinking maybe i need to skim bed it, tried a few different torque settings no difference in groups. one thing i noticed from when the gun was new to now after 500 shots or so, the throat is somewhat longer, when the gun was new the 75amax measured 2.410 after approx 500 rounds the measurement is at 2.425, been shooting them at 2.405. load is either 24gr or 24.5gr varget. i know i am missing something, i tried neck and full sizing,, the only thing is that i am not 100% sure is the primers, if they were 205m or 205, tonight i fired 50 rounds with the regular fed 205's, next time i will try the 205m's

Chet

ps i forgot to mention the groups are around 1" now at 100yds, the 55vmax shoots tight, but i am going to be shooting between 450 and 500yds and don't feel confident with the 55's out there

When you push heavies hard the throat moves. How many firings since you annealed.

maybe 10 times with different brass , but all the same headstamps, when i use a pr of pliers on the necks they take a set to oval, they do not spring back, if you think annealing will help, i will give it a shot, i do have 100 new Lapua brass i did not open yet. funny thing is i loaded 5pcs of 55 vmax with 25varget for my AR at a length of 2.250 and it shot phenomenal, i did not try jamming the 75 into the lands, is that worth a try, or will i possibly get a pressure spike, i check my loads on my runout gage, max is .001

Clean your barrel with a good carbon remover then clean the copper. In my mind nothing has changed. so it could be a dirty fouled barrel. Load the new brass and work up a load. OCW is a good way to do that in my opinion since long range is your goal. I shoot master scores with a 223 LRPV. I use 80 grainers with R15.

Edited: Touching the lands is a good place to start your load workup.

With the 3'' plate, is it possible that a screw is contacting barrel.

I have never had luck with the Hornady bullets, so I switched to Sierra's 60gr. Varminter, over 24gr. IMR4895, shot 0.25-0.30 @100 on a regular basis but could not buck a stout wind @200. Stay with 75-80 gr. for longer distances, you will have much better results.
If you really want to see better targets try some Berger bullets. Pricey but the consistency will amaze you both in measurement and targets.

hi robonhood
i will try cleaning my barrel more although, i am getting no copper after about 10 min of using boretech eliminator. what twist is your barrel, i know it sounds dumb, but i do find the OCW method confusing,

Chet

sir

i do have a few bergers, as you say they are expensive, before i take my next step in purchasing the bergers, maybe i will look into trying the 77gr sierra or hornady, out of my 9 twist

Chet

hi short round

i like that name, did i hear that somewhere on one of the Indiana jones movies LOL, but there are no issues there on barrel contact

Chet

Quote:

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Originally Posted by chetc

hi robonhood
i will try cleaning my barrel more although, i am getting no copper after about 10 min of using boretech eliminator. what twist is your barrel, i know it sounds dumb, but i do find the OCW method confusing,

Chet

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7 and 9

do you think the Sierra 77 hpbt are worth a try in the savage 9 twist. i cleaned the barrel again, going to JB bore paste the barrel and try the 75 amax again before i give up on them, just don't know how i can go from these bullets shooting under 1/2" to over 1", check bedding no binding or flexing the stock, i doubt it is the scope, because it packs the 55's

Chet

A 1:9 twist is really not conducive to a bullet over 70 gr., some may have luck with them but most will not.
Try to stay with the 70 and under. If it shoots the 55's why change, shoot what works.
If you are determined to shoot the heavies then you need a 7 or 8 twist barrel preferably the 7.

If I read your OP correctly, you are chasing the lands to get a consistent seat depth off the lands, yes? IF so, you are loading the bullet further out, thereby creating more space in the cartridge and dropping pressures. Maybe you need to work the load again, from the start at the new seating depth.

Otherwise, as froggy wrote, 9 twist and 75 amax or 77 SMK is marginal to begin with (see other posts on the subject). If you drop down to 69 SMK or TMK you'll have much better luck. Mine liked 69 SMK and 8208XBR and easily hit 750 yds steel, and the TMK shoots much flatter.

Quote:

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Originally Posted by rjtfroggy

A 1:9 twist is really not conducive to a bullet over 70 gr., some may have luck with them but most will not.
Try to stay with the 70 and under. If it shoots the 55's why change, shoot what works.
If you are determined to shoot the heavies then you need a 7 or 8 twist barrel preferably the 7.

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Rather than confusing him with "weight" talk, lets clear the issue up. Weight really has nothing to do with stabilization, LENGTH is what needs stabilized.
The 77gr bullets are notably shorter than the 75gr Amax.