Big bore load development process

[fourfive8]

Here's a handy gauge for judging/determining headspace, sizing and case length when reloading for a particular rifle (chamber). I think Wilson and possible others make a similar gauge but while those gauges can check "standard" headspace and "standard" case length for a particular cartridge they cannot check for exact headspace, sizing and case length for a cartridge in an individual rifle chamber. If you have a chamber reamed for a rifle build, you can ask your smith to make one with the extra length of barrel from the blank and the reamer he used for cutting your chamber. The beauty of this type gauge is that several things can be checked during the reloading process, if needed, and finished rounds don't have to be cycled through the rifle's chamber to determine fit... simply because it is a duplicate of the rifle's chamber.

When a friend, who is a smith, and I were threading, facing and reaming the chamber on my 450 Watts build, we used a piece of the blank to make this gauge dedicated to this rifle's chamber.

Pics show
1- head of gauge showing belt shoulder
2- new case dropped into gauge, gravity only
3- fired case dropped into gauge that shows sizing required for friction free
chambering, gravity only
4- resized and fully prepped showing case head, gravity only
5- resized and fully prepped showing case mouth, gravity only
6- loaded round, gravity only
7- loaded round, gravity only

 

[bruce moulds]

and a collet die fixing that problem will cause case head seperations.
bruce.

 

[fourfive8]

and a collet die fixing that problem will cause case head seperations.
bruce.

How? On both belted and beltless cases, the case body just forward of the web will expand to the point where resizing is required to chamber the round- either from repeated work hardening or high pressure. A regular push resizing die presses both rearward and inward in the process of resizing that portion- the portion just forward of the web. With a belted case, a regular resizing die simply won't reach that area immediately in front of the belt so the collet die does the resizing there- just forward of the web. More power to you if you have a cartridge/rifle combination that at some number of firings doesn't require resizing that area just forward of the web for resistance free chambering, be it belted or non-belted.

The only way to prolong (NOT ELIMINATE) thinning and separation at some unknown number or firings due to repeated or high pressure firings in that part of the case, no matter if it is a belted or not, is to not resize it. If you don't resize that area, no matter if it is belted or not, sooner or later expect stiff chambering. Even if you only neck size your ammo sooner or later it will not chamber without resistance. The cumulative pressure (s) exerted on that portion of the case causes the brass to thin and flow forward, the only direction it can flow. That happens because of pressure, not because of the method of resizing. Actually the collet sizer is less stressful to the case than is regular push resizing.

So two choices-- either don't resize and pitch the brass when chambering resistance is noticed or resize the brass so it can be used without chambering resistance. The method of resizing either with a regular push sizer die or a collet die is immaterial to the question of case stretching, thinning or separation. If loading for target or plinking ammo- who cares if a round now and then is balky at chambering. If loading for DG ammo, most would agree it's not acceptable to have balky chambering.

 

[fourfive8]

Here's a belted fired case next to a non-belted fired case. Left is 450 Watts, right is 270 Win. The forward edge of the web shows but have to look closely- it is the interface between the shiny and scuffed surfaces. The white line points to the forward web edge on the belted case. Note that the forward web edge on the belted case is in nearly the identical location as the forward web edge on the non-belted. The issue is that the belt gets in the way of a conventional sizing die when trying to re-size that area when resistance to chambering is felt. The conventional die sizes right over that edge on a non-belted case. A conventional die WILL NOT size over that web edge on a belted case, even though the edge is in the same location in both non-belted and belted cases.

The best way to size that relatively small, specific area just forward of the belt is with a collet die. The cost of the tool has nothing to do with how it works nor it's effectiveness in dealing with that one specific sizing issue. Although that differentiation seems to get lost in the discussion of this subject. I too swallowed hard and just gritted my teeth when I purchased one a few years ago. But it has saved a bunch of waste of expensive brass and ensures trouble free feeding of the belted DG cartridges I shoot.

 

[CoElkHunter]

why would I need that? The cases rechamber fine. Also, that die won’t fix head thinning ahead of the belt.

Yeah, I don’t see the point of using the collet resizing until the cases won’t rechamber anymore (for practice loads). Maybe by then the cases are done anyways? Maybe not, use the collet die then?

 

[Opposite Pole]

Yeah, I don’t see the point of using the collet resizing until the cases won’t rechamber anymore (for practice loads). Maybe by then the cases are done anyways? Maybe not, use the collet die then?

In some rifles belted cases are done (stop chambering) after second or even first firing, with the use of this die, correct sizing and neck annealing you can get 15 or so. If the resized case chambers there is no need to use the collet die although it won’t hurt. One side of the belted collet die is actually a SAAMI spec case gauge so you can easily verify it the case needs this extra step or not.

 

[CoElkHunter]

In some rifles belted cases are done after second or even first firing, with the use of this die, correct sizing and annealing you can get 15 or so.

Thanks for this information. I’ve never annealed cases before. I’ll have to look into this process.

 

[Opposite Pole]

Thanks for this information. I’ve never annealed cases before. I’ll have to look into this process.

I use the AMP annealing machine, it takes the guesswork out of it - you sacrifice one case of the lot to measure the melting point and thus establish the exact heat time for the particular lot of brass. The machine gives repeatable results, is so far reliable and above all I like gadgets.

 

[CoElkHunter]

Here's a handy gauge for judging/determining headspace, sizing and case length when reloading for a particular rifle (chamber). I think Wilson and possible others make a similar gauge but while those gauges can check "standard" headspace and "standard" case length for a particular cartridge they cannot check for exact headspace, sizing and case length for a cartridge in an individual rifle chamber. If you have a chamber reamed for a rifle build, you can ask your smith to make one with the extra length of barrel from the blank and the reamer he used for cutting your chamber. The beauty of this type gauge is that several things can be checked during the reloading process, if needed, and finished rounds don't have to be cycled through the rifle's chamber to determine fit... simply because it is a duplicate of the rifle's chamber.

When a friend, who is a smith, and I were threading, facing and reaming the chamber on my 450 Watts build, we used a piece of the blank to make this gauge dedicated to this rifle's chamber.

Pics show
1- head of gauge showing belt shoulder
2- new case dropped into gauge, gravity only
3- fired case dropped into gauge that shows sizing required for friction free
chambering, gravity only
4- resized and fully prepped showing case head, gravity only
5- resized and fully prepped showing case mouth, gravity only
6- loaded round, gravity only
7- loaded round, gravity only

View attachment 320760
View attachment 320775 View attachment 320776 View attachment 320777 View attachment 320778 View attachment 320779 View attachment 320780

Just curious, why the Watts cartridge vs. a Lott? I find the “wildcats” intriguing so just asking?

 

[fourfive8]

Just curious, why the Watts cartridge vs. a Lott? I find the “wildcats” intriguing so just asking?

No particular reason and maybe not even a practical stretch "what if" reason other than it seemed the most universal of that category of 45 cal cartridges that would fit in the Montana 99 action I had. And IIRC it has some history in Africa dating back into the early 1950s. I think Jack O. used one for DG in Africa. In fact it was never promoted and probably came before its time. The Lott was later promoted, became a standardized cartridge and filled that niche. If needed, both the 458 WM and 458 Lott can both be shot in the Watts without issue. The next longer 45 cal basic belted mag would be the 458 Express which, IMO, seems a tad too long and really limits the COAL options with some bullets. But a nice thing about these basic belted mag cases is if they are a little too long with some bullets, you can simply trim them shorter, seat the bullet and go- within reason of course. And, no way of knowing for sure but I can use practically all published Lott data, no matter the bullet or powder, without any pressure issue. Don't know if it is my particular chamber, throat specs or bore but sure seems that way. Nice to not have to worry about potential pressure problems.

And yes, as Opposite Pole pointed out, annealing cases can really extend their useful lifespan if you take care in the annealing and resize correctly. The secret to annealing is knowing the best temp range and area of case to anneal and procedure to do it correctly. I've done it for years on quite a few large cases without issue and some of them, like one batch 45-70s used for low pressure loads, have countless firings, certainly north of 40 or 50. The theory is to soften the neck/shoulder area just enough so it doesn't split because of work hardening and to not soften the body where it needs to remain hard. Here's an annealed 450 Watts. Also, I think the annealing "colors" show on new Lapua cases as they anneal as a last or near last step in their process and don't polish away the annealing color hues.

 

[tarbe]

Also, I think the annealing "colors" show on new Lapua cases as they anneal as a last or near last step in their process and don't polish away the annealing color hues.
View attachment 320868

All of the 450-400 NE Hornady cases I have purchased also showed the annealing colors.

 

[CoElkHunter]

All of the 450-400 NE Hornady cases I have purchased also showed the annealing colors.

Yeah, the new (old stock) Winchester .458 WM brass I bought also shows this, but the new Norma .458 brass doesn’t? What’s up? Maybe the Winchester brass is slightly thinner?

 

[Opposite Pole]

Yeah, the new (old stock) Winchester .458 WM brass I bought also shows this, but the new Norma .458 brass doesn’t? What’s up? Maybe the Winchester brass is slightly thinner?

It’s most likely the post annealing treatment/polishing.

 

[CoElkHunter]

This might be a little off topic for this thread, but some of you might still be awake and I’m at an impasse? I started loading some 350gr Speer Hot Cores in my .458 WM tonight. The bullet is short. If I seat the bullet at the cannelure, the coal will be about one quarter inch shorter than a factory cartridge. Crimp it where it’s at? Not much bullet in the case though? HELP! Thanks!

 

[Forrest Halley]

This might be a little off topic for this thread, but some of you might still be awake and I’m at an impasse? I started loading some 350gr Speer Hot Cores in my .458 WM tonight. The bullet is short. If I seat the bullet at the cannelure, the coal will be about one quarter inch shorter than a factory cartridge. Crimp it where it’s at? Not much bullet in the case though? HELP! Thanks!

So I shoot a really light .45 LC and it has the same nose profile as a 250 grain. I think the base is short to keep the weight down and the feeding positive or reasonable.

 

[fourfive8]

Yah, if you're confident in the quality of the crimp, I'd just crimp in the groove and shoot it. Load the mag full and shoot all but the last round then either measure the last or visually inspect it for any bullet movement. If the mouth edge moves relative to the cannelure it is easy to see. For magazine rifles, it's usually best to crimp the mouth edge up against the front edge of the cannelure. There shouldn't be much issue at all for a slightly shorter COAL. Let the chronograph and target tell the story, while being mindful of the pressure signs.

 

[CoElkHunter]

Yah, if you're confident in the quality of the crimp, I'd just crimp in the groove and shoot it. Load the mag full and shoot all but the last round then either measure the last or visually inspect it for any bullet movement. If the mouth edge moves relative to the cannelure it is easy to see. For magazine rifles, it's usually best to crimp the mouth edge up against the front edge of the cannelure. There shouldn't be much issue at all for a slightly shorter COAL. Let the chronograph and target tell the story, while being mindful of the pressure signs
Thanks!

 

[CoElkHunter]

Thanks! If I crimp in the cannelure, the coal will be one quarter inch shorter? I also sent an email to Speer, so while I’m pondering your suggestion and waiting to hear back from Speer, I’ll go to the other bullet length spectrum and try and load some 450gr Barnes?

 

[fourfive8]

Can't imagine any problem if you stay within the load parameters. Speer shows a COAL of 3.105" in their data for their 350 gr bullet in the 458 WM.

The nose length- from the front of the last groove to the nose for the 450 Barnes TSX is .86" so adding that to a trim length of the WM of 2.490" = a COAL of 3.35" which us just .01" over the listed max for the WM of 3.34". Unless something is too "tight" in your rifle that is plenty close enough so it should work fine for length. Most 458 WMs have a long throat and .01" shouldn't matter at all for magazine clearance or feeding.

 

[CoElkHunter]

Can't imagine any problem if you stay within the load parameters. Speer shows a COAL of 3.105" in their data for their 350 gr bullet in the 458 WM.

The nose length- from the front of the last groove to the nose for the 450 Barnes TSX is .86" so adding that to a trim length of the WM of 2.490" = a COAL of 3.35" which us just .01" over the listed max for the WM of 3.34". Unless something is too "tight" in your rifle that is plenty close enough so it should work fine for length. Most 458 WMs have a long throat and .01" shouldn't matter at all for magazine clearance or feeding.

View attachment 321071

Thanks for further clarifying this. I used a factory Barnes 450 TSX cartridge when setting up my bullet seating die, so the coal would be the same. But obviously, this didn’t work for the shorter Speer bullet? I also have factory Nosler 500gr and they are the same or very close coal as the Barnes 450gr, so when I load 450 and 500gr TSXs, the coal will be the same. The shorter Speer threw me for a loop! I’ve never loaded straight walled rifle cases before, so I’ve been careful and apprehensive? I’m using 78gr (started to use) of W748 for the 350gr, but now I’m not sure about that, as I’m extrapolating that load from the 500gr 748 published load in my Hornady reloading manual. 78gr is a medium charge for the 500gr bullet, so I should be ok with the 350gr bullet? Big bore load development! Ha! Ha!