Tight neck questions

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Re: Tight neck questions

Postby Hoot » Fri Jul 06, 2018 11:06 am

This gives me an idea for a range experiment given the nice weather predicted tomorrow (Saturday).

I have a 450b Lee FCD. Since I already have recent data for the 200 FTX vs 200 xpb done with a regular taper crimp, applied at the mouth. if I'm not out of 200 ftx bullets, I could add tests using the 450b Lee FCD applied to the mouth. Still have some 200 xpb's left, but I'm not sure how that wide crimp will behave if the driving band groove is narrower than it. If it catches the band, it won't go down into the groove.

I'll check when I get home.

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Re: Tight neck questions

Postby Hoot » Sat Jul 07, 2018 6:57 am

Hoot wrote:This gives me an idea for a range experiment given the nice weather predicted tomorrow (Saturday).

I have a 450b Lee FCD. Since I already have recent data for the 200 FTX vs 200 xpb done with a regular taper crimp, applied at the mouth. if I'm not out of 200 ftx bullets, I could add tests using the 450b Lee FCD applied to the mouth. Still have some 200 xpb's left, but I'm not sure how that wide crimp will behave if the driving band groove is narrower than it. If it catches the band, it won't go down into the groove.

I'll check when I get home.

Hoot


Game Change. Hoot is going to be self indulgent today. About 9 years ago, I got a good deal on a .260 Rem barrel for my Model 12's. Believe it or not, its sat in the gun cabinet, mounted on one of my Model 12's ever since I got Black Rifle Disease! Well my rich brother in law bought a Ruger Precision Rifle in 6.5 Creedmoor and though he hasn't shot it yet, he's already trash talking the 260 Rem. The gauntlet is down! We're going to have a shoot off.

So I'm going to the range on a Blue Jay Purdy Day (currently 67 headed to 80) to see what my 260 likes. Thanks to my 6.5 Grendel, I have a good selection of .264 bullets on hand. Going to start off with 100gr NBT and a favorite bottle neck powder albeit not widely promoted, Alliant AR-Comp. Highly temperature compensated and good timing as its summer. After today's meet n greet, I'll move up to 120 NBT next time out. Something to fiddle with while my 450b cools down on subsequent range days.

Back to 450b next Saturday...

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Re: Tight neck questions

Postby Al in Mi » Sun Jul 08, 2018 7:54 am

Hoot wrote:
CJP1 wrote:Hoot,
Thanks for the insight on the TNT. I thought it would be the end all to keeping bullets secure in the brass...snip....


So did I. sigh...

It's not a reach to realize that heavy crimping distorts bullets giving them a waspish figure. At least the cup and core ones. The less appreciated damage is what happens to the case mouths. The mouth is where the case wall is the thinnest. Repeated heavy crimping there thins them even more, leading to a vicious cycle or needing more crimp, causing more thinning, needing more crimp. causing more thinning, etc. the Thinning is not in leaps and bounds, like squeezing a rolled up ball of chewing gum but it does happen, especially with solid copper or solid brass bullets. Its a cumulative effect. That's why any opportunity to crimp down into a driving band groove or cannelure is a saving grace.

Al, I seem to remember someone reporting on their experience with a 450b Factory Crimp Die right at the mouth.

I've also experimented with using a resizing die as a taper crimp. The reason you may have not noticed a report on that was despite doing the job, it provided no benefit that I could tell. Somewhere I have some target scans of the groups. IIRC, they were on par with groups provided by a taper crimp die. Certainly didn't help with velocity SD's either. Try the resizing die sometime yourselves. It works.

About the only thing I have yet to try is sealing compound like Markron sells. According to them, it doesn't effect pressure, so never felt like giving it a try.

Hoot


Anybody know what black stuff is that the military puts in the case necks of their ammo? I'm assuming its for waterproofing but wondering if it might help with bullet retention.

Back in my 410 ICBM days, with the slick inside of the hulls we would use pruning tar on a Q-tip and lightly do the case mouth after dumping powder, then give the bullets a quick lick of it, seat, crimp, and let sit for a day or two. Cut extreme spreads in half with the Varget load we used.


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Re: Tight neck questions

Postby Hoot » Sun Jul 08, 2018 8:05 am

Al in Mi wrote:...snip...

Anybody know what black stuff is that the military puts in the case necks of their ammo? I'm assuming its for waterproofing but wondering if it might help with bullet retention...snip...


Asphalt

Pruning tar would probably be as good a representation of it as any consumer product.

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Re: Tight neck questions

Postby CJP1 » Sun Jul 08, 2018 3:45 pm

Hoot,
I also have the Lee 450b FCD as I bought the Lee die set first. As I recall, it over crimped the mouth and not the rest of the taper like the Hornady taper die does. Let us know what you think of the Lee FCD. If you find that it doesn't work, do you think that my 450b FCD could be modified to a side crimp die. It adjusts by running the die up and down in the press. It only has 3 pieces. The main body that is threaded and knurled, the 4 fingered taper insert and the jam nut with o ring. I really didn't want to go that way but I haven't gotten good crimps on the bullets.
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Re: Tight neck questions

Postby Hoot » Sun Jul 08, 2018 7:25 pm

CJP1 wrote:Hoot,
I also have the Lee 450b FCD as I bought the Lee die set first. As I recall, it over crimped the mouth and not the rest of the taper like the Hornady taper die does. Let us know what you think of the Lee FCD. If you find that it doesn't work, do you think that my 450b FCD could be modified to a side crimp die. It adjusts by running the die up and down in the press. It only has 3 pieces. The main body that is threaded and knurled, the 4 fingered taper insert and the jam nut with o ring. I really didn't want to go that way but I haven't gotten good crimps on the bullets.


You can mod the 450b specific die just as easily as the other ones used to make a stab crimp. Having done at least 20 of them, I'm intimately familiar with the working parts. Its a lot easier in some respects to do it with a lathe, but the hand method I chronicled in the sticky works as well. I didn't get to mine this weekend as I was messing around with my 260 Remington. Forgot how much fun bolt guns can be. I don't think it is intended to be the only crimp you apply for exactly the reason you cited. The taper crimp doesn't just push the mouth in as you also noted. It tapers the case down quite a ways. I would suspect that the best approach would be to taper crimp it and then apply the mouth crimp as an adjunct to the taper crimp, not a replacement. I may get a chance to play with it next weekend, but I have to spiff the place up as the Mrs is coming back from being gone for 2 weeks. Either that or have a sign made for the front door that reads
Bears With Furniture

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Re: Tight neck questions

Postby CJP1 » Tue Jul 10, 2018 7:18 pm

Hoot,
How much material should I cut off of the bottom of my 450b Lee FCD body and the four fingered insert as I assume it is shorter than the 45-70 die? I would like to crimp into the driving band grooves of the Barnes bullets. I can load them longer as my magazine is longer than AR mags. I also will need to narrow up the crimp face and round the edges. Thank you for your help.
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Re: Tight neck questions

Postby Hoot » Tue Jul 10, 2018 8:39 pm

CJP1 wrote:Hoot,
How much material should I cut off of the bottom of my 450b Lee FCD body and the four fingered insert as I assume it is shorter than the 45-70 die? I would like to crimp into the driving band grooves of the Barnes bullets. I can load them longer as my magazine is longer than AR mags. I also will need to narrow up the crimp face and round the edges. Thank you for your help.


Easy question. Measure how far down the case you want the crimp to be ad remove that much from the four fingered collet bottom. The trickier part is narrowing the bite you don't want a tenth of an inch crimp width which is about what it comes as. Removing that metal is as much art as it is science. If you have access to a lathe with small cutting tools, its a breeze, compared to grinding away with tapered stones and the drill press, as explained in the stickied thread Here. Read all of it as there were some useful tidbits offered up after the main body, including the Sequel.

A lot of members move the center of the stab crimp down a .1 inch below the mouth and necessity dictates that the bite be narrowed down to around .025 wide, in order to produce an indentation on the inside of the case of .050 or thereabouts. That's the dimensions I shoot for.

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