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Would You Keep Going?

I have a few improvex cases. I dont load to see what the max can be... I usually gain 50-100 fps BUT i am mostly concerned with gaining accuracy by opening my accuracy window more and consequenty sometimes lowering pressure

As stated above, game anx targets really dont know they were hit with an additional 100 fps.
 
Why even bother to go the Ackley Improved route if not for gains in velocity. Granted, the case might have a little less stretch after multiple firings, but that is an unrelated benefit to the velocity gain.

The primer is the one thing you can read that is subjected to the actual chamber preasure. Judging from the roundness of the corners and the lack of overall flatness, it I’d pretty obvious that the OP is not in any danger zone.

Simply put, it’s the firing pin to hole clearance causing that crater. Most do not want to admit this because it is a mechanical issue and is not something you easily fix, without the proper tools and skill.
 
Thanks for all the replies. Seems the consensus is the bolt needs bushed.

It seems some people don't get the point of the pressure test. The point is not to end up with a final load at max on the verge of danger just to get a few more FPS. The point is to find where that is and NEVER be close to it ever again. Then start accuracy testing from a moderate charge up to the now known safe and sane stopping point.

I have yet to end up with a final load beyond the highest max I have found published, but I always pressure test beyond that to make sure for example if its 100 degrees out and I worked up the load in 55 degrees im not gonna be popping primers or something.

The case fill at the max I tested is visually the same as book max for regular 223 in the same lot of brass. I'm not a ballistician, but I figured max for 223AI would be a similar case fill.
 
Its a tikka action. Its rem 7.5. I'm not pushing for max velocity. I know im close. Powder is up to the base of the neck. I just want to decide where pressure is and never get close to that again. Cratering is a sign of pressure. This is a little more than I have seen before, but even some factory ammo craters and flattens primers in various guns I own. Accuracy testing is the next step. Heck gonna be hard to beat the random fireforming load.

Im trying to get better at looking at pressure. I didn't give the full details, cuz I want to know what you see. Im positive a bunch of people here have kept on going till they are smacking the bolt open with a hammer and popping primers, and they have done it multiple times. I haven't been loading that long, so I am always on the side of caution.
On other rifles with 7.5s my primers looks like that. My 20p pushes 40s over 3900 looking like that in a ruger mk2.

I have a t3 action as well. I use 7.5s but i believe mine is bushed. H335 gave better velo than 133. Saying that my primers never flattened. I got above the manual for regular and went to .3 increments until I found signs. I got to slight bolt resistance and knew where I was at the top and to stay below. Still not flattened but wasn't going to try any higher. This was in lc223 brass. I could use over .5 gr more than fc brass in the lc brass and didn't get to the slight sticky bolt lift I got in the fc brass.

There's probably more left if you choose to try and find it being safe.
 
Dont get too greedy in a 223a. If you want the primer pockets to last. That cartridge doesn't show much pressure until you are already hurting the pocket.

Especially with those thick primers.

Those Remington 700 firing pins are an excellent pressure indicators. Just shoot it where it's happy and not piercing.
 
I believe it was Barsness that did some testing a several years ago with a strain gauge.
All the measuring and looking at this that and the other meant little, compared to what the strain gauge showed.
I have mentioned the 280AI before, it did things way over and above the parent case. It’s a wildcat, so do what we may do with them. It came around as a SAMMI cartridge and because of pressures, it does little more than the parent when factory ammo is used.

Something I have not seen touched on by anyone is chrono readings?
As to my knowledege, there is no way around speed and pressure, the two run hand in hand.

Ackleys initial intent with his improved cartridge idea was to clean up and better center the chamber to the bore in some sloppy work. The extra case capacity was just a bonus.
 
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Primer is not flattened at all. I see no marks on the brass and bolt lift was just fine. The first cratering started .5 gr before this.
Maybe a "headspace issue"? not "chamber" but brass a little too short for the chamber? Primer/round goes BANG, brass moves back in the chamber against the bolt bead while primer tries to back out of the pocket gets cratered or pierced?
Me? Start there if no pressure signs. Start with the easy stuff FIRST before you start/end up chasing your tail.
I know, me "beating a dead horse" but, I've seen it happen LOTS OF TIMES and folks get caught up in it and skip the easy stuff. KISS. ;)
 
Measured 5 unfired pieces from the same lot just above the extractor groove and all cases from the pressure test measure the same as far as I can tell using calipers.
 
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What you expect from brass life depends a lot on your statement of not wanting to "prematurely wear out your brass". Backing off a few grains from "max" will usually yield significantly longer brass life. I do a lot of brass prep on most of my varmint brass, including turning the necks, etc. and I want them to last at least 6 or 7 firings in my A/R's. That requires running at least a grain or two below any signs of pressure.
 
Thanks for all the replies. Seems the consensus is the bolt needs bushed.

It seems some people don't get the point of the pressure test. The point is not to end up with a final load at max on the verge of danger just to get a few more FPS. The point is to find where that is and NEVER be close to it ever again. Then start accuracy testing from a moderate charge up to the now known safe and sane stopping point.

I have yet to end up with a final load beyond the highest max I have found published, but I always pressure test beyond that to make sure for example if its 100 degrees out and I worked up the load in 55 degrees im not gonna be popping primers or something.

The case fill at the max I tested is visually the same as book max for regular 223 in the same lot of brass. I'm not a ballistician, but I figured max for 223AI would be a similar case fill.
I never spent the money to bush my Rem 700 bolts. I feel it's just cosmetic and not a problem. Millions of Rem made that way.
 
Thanks for all the replies. Seems the consensus is the bolt needs bushed.
Don't get in too much of a hurry on this. I'm going to go out on a limb here and say, I think you may just need a slightly stiffer firing pin spring.
In looking at your fired cases, there is no indication at all of an overpressure load. The so called "cratering" that you're looking at is really not serious at all. I definitely wouldn't consider bushing the bolt.
 
Don't get in too much of a hurry on this. I'm going to go out on a limb here and say, I think you may just need a slightly stiffer firing pin spring.
In looking at your fired cases, there is no indication at all of an overpressure load. The so called "cratering" that you're looking at is really not serious at all. I definitely wouldn't consider bushing the bolt.
Could be the firing pin spring. I think I bought the rifle in 2008 or 2009. The spring spent most of its life in the cocked position before I knew better and it has 5k or so rounds fired. Unfortunately, on a Tikka its not easy to just change out the spring or I would.
 
A side note: several years ago I had the opportunity to buy two 30lb (18" diameter by 24" tall) cardboard containers full of 5.56 once fired brass. Fired from M-16's, but not much was full-auto. WW Small Rifle Primers were about $8 per thousand if you bought them in bulk. We used to drive up to Speer in Lewiston and buy bulk cosmetic second 55gr soft points for about 3-cents apiece by the tub. I spent most of my winter that year prepping brass with one of the Lee depriming tools while watching college basketball on TV. I still do my prep work that way, sort-of. Just an Arbor Press these days. I used to load using the military once-fired dimension for reference. When I hit that mark I backed off 1/2grain. It was just 1 moa accurate, but I never missed a ground squirrel out to 300 yards. That was as far as I used the load. By the second day, it was my 219 Zipper Improved, or the 6mm Remington.
I'm still shooting that stuff.
 
Just for clarity, what is your intent with this particular 223AI? Is it a complete rebarrel with a fast twist for heavy bullets for long range or rechambering the existing barrel to get more velocity?

I ask because I built a new rifle a decade or so back in 223AI for using 80 grain + bullets. I wanted it to surpass a 223 using heavy bullets and it has, but not by some huge margin. The side benefits have been never having to trim cases, some extra velocity, an absolutely sexy little cartridge, and since I hate money a temporary depletion of my rifle slush fund. It has been as accurate as I hoped (it better have been this as it cost enough), but in hind sight I could have built a 22BR. Now a days a 22 ARC would be my huckleberry, but please don't mention this to me.

I agree with 92.5% of the responders that bushing the bolt would very likely make the crater disappear. IMHO there is no downsides to doing it except for downtime on the rifle a some $. GreTan got to do every Remington 700 in my safe and a couple Surgeons (they used large firing pins in the beginning) years back. Heck I bushed some bolts that had never shown a crater. As I mentioned I hate money and love uniformity.
 

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