Interesting. Recently shot a PRS22 match where I slammed my RimX in an XLR Envy Pro (not bedded) into a small slot on a PRS barricade and my zero shifted 1.2 mils (saw the misses on rest of that stage then went to zero board and rezeroed). I assumed the scope internals shifted but maybe the RimX barrel action shifted in the non-bedded chassis?
Foundation Stocks - people are bedding?
I've seen a few guys saying they fully bedded their Foundation Stock. Anyone care to explain their decision to do this? Peace of mind? Poor mating/accuracy without? I just placed an order for an exodus. I've only shot chassis's and Foundation states their stocks don't require bedding/pillars...www.snipershide.com
its pretty easy to tell if its tied to performance/reliability
hit tf out of the barrel on something and shoot it
my sample of one MPA would shift all over
none of my foundations exhibited a shift
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That doesn't make any sense (to me). Assuming the barrel is torqued in place, how would the barrel shift in the action?
The issue isn't alignment in the barrel to action interface. I don't know what the thread size and pitch are in a Rimx off the top of my head but I'm sure they're substantial. Which, coupled with proper torque, would make for a pretty robust joint. I'm no joint engineer but the thought that the barrel shifted in the action has no basis.
It doesn’t need to make sense to you to be a highly probable reason. The fact remains, threads are the WORST method of maintaining alignment between two objects. Add impacts to either of said objects, and the likelihood of misalignment increases dramatically. What did you torque the barrel to?
I'm not the person you originally responded to but I generally will torque the barrel to the action manufacturers specs. For my CDG action that's 125ftlb.
Again, I don't think this has anything to o with alignment. The tension in the joint is going to keep the barrel from being "misaligned" or moving at all. What do you think the barrel needs to be aligned to?
EDIT: Also to be clear I'm not disagreeing with your assertion that threads are not good features to use for alignment. My argument is that it doesn't matter.
What do I think the barrel needs to be aligned to? Ummm, the reticle, and that absolutely matters.
Maybe some folks stress over it but I'm not aware of anyone who is concerned with barrel to reticle alignment. Generally the reticle is aligned to the POI, thus the POA is aligned to the POI. You torque the barrel on the action and then adjust the optic so that POI = POA. The barrel is not aligned to anything it ends up wherever it ends up.
The important bit in the above poster's scenario is not alignment of the barrel, its that some component somewhere in the system has moved. So some joint somewhere has slipped. I'm arguing the barrel to action interface is immaterial because it's very unlikely the joint there would have slipped. As an example a 1.125 threaded joint tightened to 50 ft-lb (arbitrary) results in a bolt tension force of ~2600 lbs. I'd wager it's more likely something in his optic shifted or in his chassis. Anecdotally, I've wacked my barrel plenty of times in PRS stages and continued to hit targets at distance with no shift in POI.
Yeah, the barrel moved, relative to his reticle.
“Barrel alignment to reticle doesn’t matter.”
It’s literally the only thing that matters. POA IS THE RETICLE. WTF do you think you're aiming with, if not the reticle?
“Barrel alignment to reticle doesn’t matter.”
It’s literally the only thing that matters. POA IS THE RETICLE. WTF do you think you're aiming with, if not the reticle?
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Between the reticle and the barrel there are several joints. Inside the scope, rings, mount/rail etc. Assuming it could only be the barrel moving 1.2mils is silly.
That's not what you said though.
I've been addressing your suggestion that the barrel shifted in the action.
If you have an angular difference of the POA between the reticle and the barrel there will be a linear difference in the POI that will get greater with greater range. Simple geometry, right?
I didn't suggest it was the ONLY possibility, just that a consistent shift in one direction likely isn't a lack of chassis bedding. Do think 1.2mils is a lot?
Which of those other joints suffered the brunt of this barrel impact?
What you're saying is simple geometry yes. However that's not the point I was trying to make at all. My point is that the concern is not aligning the barrel to the reticle. The barrel is torqued on and ends up pointing in some direction. That direction may be influenced by machining tolerances, debris in threaded interface, lubrication in the joint, etc but all that does not matter. Generally the barrel is not made to point in a specific direction (generally speaking). The reticle is what is adjusted and aligned to the POI. Which is related to the barrel direction but not the alignment of the barrel.
It's semantics but I think it's important to be accurate with the language.
Until you smack it off something and it’s only torqued hand tight.
I mentioned in an earlier post that I was assuming it was torqued on. Again this is an assumption so I can't claim it as fact in the previous poster's scenario but I'd be willing to be the vast majority of barrels out there are torqued on not just screwed hand tight. Even if it was hand tight, I'd still be skeptical that it would shift 1.2mils. I rarely ever torque suppressors on with tools and just put them on hand tight (direct thread with no mounts). They don't seem to move at all.
I've seen barrel impacts move POI more than a mil. More torque is more insurance against it but it really just comes down to how hard you hit the barrel vs. how tight it is, thread fit, shoulder area, etc.
It's a thing that happens, seen it done, done it myself. It doesn't take much movement over the threaded section to make relatively big shifts at 100yd+.
It's a thing that happens, seen it done, done it myself. It doesn't take much movement over the threaded section to make relatively big shifts at 100yd+.
Barrel specificly impacting the prop? A 1”+threaded joint vs all the other weaker joints in the system? Sure, that must be it.
Where I question it is not whether an impact to the barrel can shift POI but whether it's the barrel moving in the action. There's a lot of other joints in the system that would slip before the barrel moves in the action. That's my assumption anyway I don't have any data to back it up except for anecdotal experience.
Interesting.
Did you miss the part where more barrel torque meant less shift? If it's not the barrel moving, why would barrel torque have an effect?
Yeah, no. Definitely the barrel moving. This was the primary issue back in the days of Barloc and WTO Switchlug. If you couldn't get joint stiffness they weren't robust at all. It lead down a rabbit hole where Ted at ARC basically found that there was no truly safe space. If you hit the barrel hard enough it will shift.
You can also bend barrels easier than a guy thinks... but that's a different redneck party.
That's interesting and definitely changes my perspective. I'd be interested to see some studies performed on something like this. I guess I've never seen any issues because I torque barrels on everytime to 125 ft-lbs per the action manufacturers recommendation. And that manufacturer happens to be ARC. Even a hard hit to a 28" barrel with a 6" suppressor caused no shift in my system.
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