Meaningful sorting.

[jmorris]

I figure a good start would be 2 moa at 100 with a string of 5. This would be inital and once I can maintain it reduce. That shouldn't be terribly hard to achieve until applied across multiple molds. As a point of learning, I don't know if it would be more helpful to focus on one or bring all in a group to that standard. I'm also guessing a gas checked design would be easier to meet initial expectations with.

I imagine some molds/rifles are never going to get there but I have cheap Lee molds that will do that with rifles that also shoot well, even without gas checks. I get better results with hi tek coating than powder coat but that could be application methods and I made a shift in focus, following results.

As a point of learning, you could have an endless project. Ultimately I too believe a gas checked bullet will give you the best results as the base of the bullet is the most important part but 2” @ 100 yards is a lot different than 12” @ 600 in this regard.

 

[AJC1]

Would have to say one of the biggest jumps in my accuracy across the board(many different cals)is tapered nose sizing.

Give me a bore rider with a .0005-.001" oversized nose and a tapered sizer. Tapers are soooooo cool as they allow you to adjust the "jam" independently from where the bullet's base is within the case neck.

I've had some stoopid good accuracy from bullets with the base down below the case neck... so don't necessarily go along with the theory the base has to,or is best not below that point. No,what I'm sayin is....

You can really tune a HV load by changing where the taper engages chamber leade.

Another area that can make a big difference in a factory chamber is testing loaded round,neck OD to chamber clearance. Tony Boyer writes about sine wave shaped traces of blowback on a neck when he's in tune....

I've seen not just discoloration,but taken to an extreme(in tests,there wasn't a specific clearance.... each chamber/bullet/jam is a rule to itself..mostly) have seen antimony *"buggers" blown back. They're these tiny almost perfectly spherical balls that cling to the fired case neck. "Usually" that's when you get into around a total of .002" clearance....and some pretty jacked up loads. I see it more with the medium slow powders,4895,Varget,etc. Going to 4831 speed powders work better.

*antimony "wash" is where it paints the bore within the first cpl inches of the barrel.... but that's with more typical neck-chamber clearance. When that space closes up,I'm guessing here.... the "wash" turned to buggers. Real scientific huh? Haha.

I have yet to receive any real clarity on jam. I read in the rcbs manual that it's ideal with a cast load in the lands because jump more often than not leads to deformation reducing accuracy. I do desire to develop and test a load into the lands to see if it helps if I can. Obviously this would be in a bolt in a range setting.

 

[BWS]

Digging deeper,I like backhoes.....

I bought a takeoff R700 fluted SS varmint 22-250 barrel years ago. Would say it was about 75% used up... you know,right about where the original owner noticed a drop off in accuracy?

Running a tightarsed patch down this barrel... about 10" or so from chamber the patch would hit a tight spot. Checking other used "barrel burners" 243's and the like,would show this same tendency. That 22-250 barrel really woke up with a cast RCBS 60G. Just sayin,there can be some real cast life left in discarded JB barrels. Not gonna even suggest I know how to put this sheet into words....which if you got this far should be obvious.

Another tidbit is how durn picky some barrels are to a particular mould? That above RCBS 60G which is a tackdriver in that 22-250..... falls flat on its face in one particular .223

It's a ADL R700 that will bughole @100 with the Lee 225-55RF at starting JB loads of 4198.... these two moulds are pretty much identical for practical purposes. But it's so dramatic,really makes you wonder?

 

[BWS]

Jam;

Find the OAL that "sticks" about 1 or 2 percent of chambered rounds,when ejecting loaded rounds.Obviously won't work in competition but as a varmint killer.... just an inconvenience.

Jam is wholey different in cast vs JB;
Cast we get to taper size the nose. This changes EVERYTHING compared to JB's. They either have to change OAL,which dictates where their bases are....OR.... rethroat the chamber. Look at hybrid JB's difficulty in this area(jam).... heck,the factories can't even agree on hybrid seating "best practices". That's how it manifests itself. I just change the included taper angles,load up a box....step out the door and send'm downrange. It won't take reams of test data to see which that rig prefers...

 

[BWS]

Making H&I dies taught me about leades,way more than testing in rifles...

Logic would say that a more gentle leade has to be better.... classic,"it depends". Each mould(bullet) is gonna have it's likes N dislikes. Think neck tension.....

When I'm making up spuds for Lyman M dies,have settled on .002 and .004" for initial interference fit. Only after checking these two sizes does that aspect really come into focus for me..... usually there's a noticeable difference. Well, the nose taper angles are similar....

When making nose dies,while everything is setup anyway.... I use a cpl different reamers. AND not all reamers are straight tapers. Snag a 5/16" "car" reamer off flea bay. The car in this instance is rail car. In anycase they aren't a straight taper... they're elliptical. Gets way over my pay grade discussing the math. I understand it when seeing it on a bullet nose.... and know somewhere in the big picture an equation could be produced? That's all fine but you still gotta send'm.


ETA

 

[AJC1]

Digging deeper,I like backhoes.....

I bought a takeoff R700 fluted SS varmint 22-250 barrel years ago. Would say it was about 75% used up... you know,right about where the original owner noticed a drop off in accuracy?

Running a tightarsed patch down this barrel... about 10" or so from chamber the patch would hit a tight spot. Checking other used "barrel burners" 243's and the like,would show this same tendency. That 22-250 barrel really woke up with a cast RCBS 60G. Just sayin,there can be some real cast life left in discarded JB barrels. Not gonna even suggest I know how to put this sheet into words....which if you got this far should be obvious.

Another tidbit is how durn picky some barrels are to a particular mould? That above RCBS 60G which is a tackdriver in that 22-250..... falls flat on its face in one particular .223

It's a ADL R700 that will bughole @100 with the Lee 225-55RF at starting JB loads of 4198.... these two moulds are pretty much identical for practical purposes. But it's so dramatic,really makes you wonder?

Falls into the classic barrel likes what it likes classification???