460 still jumping crimp

[geomort]

In working up a loads for my 460V I chose the Hornady XTP 300 grain and the 250 grain in 454 cases. I began with new Starline brass, CCI magnum primer, and WW296 powder.
Started with 38 gr 296 in the 460 and ended at 42.5 grains.
With the 454 Cassul brass, started at 32 grains and ended with 36 grains. Velocities were 200 to 300 ft below listed values doubtless from the 5 inch barrel as opposed to the standard 8 or 10 inch models.
However, I noticed that the velocity spread at high loading density was narrow as expected for the first three shots. Shot 4 and 5 consistantly dropped in velocity 50 to 150 fps. Ammunition loaded and fired one at a time was quite uniform in velocity.
The bullets jump crimp despite my best efforts to lock them down. I had a Lee factory crimp die made for the 460 by sending in a sample Star case and XTP 300 grain bullet. A stock Lee factory crimp die was available for 454 Cassul.

What other measures can I take to hold the bullets in place?
I have a power tool to press a deeper channellure into the bullets. I can grind the belling insert to minimize expantion of the resized cases. Perhaps a different brand of brass might be stiffer. Lastly, I could roll a second channellure into the case and bullet. That would likely shorten case life to one or two loadings.

How do you lock down your full power loads?

Thanks,
George

 

[cp1969]

You could try turning down the OD of your sizer plug a couple thousandths. Would make the bullets seat harder.

But, I think I would first try a different brand of brass, if that is possible. Maybe Starline brass has thinner walls than others.

 

[buck460XVR]

I had a Lee factory crimp die made for the 460 by sending in a sample Star case and XTP 300 grain bullet. A stock Lee factory crimp die was available for 454 Cassul.

I believe this may be your problem. Sometimes with a heavy crimp, the factory crimp die actually re-sizes the bullet making it smaller in diameter, resulting in less neck tension. The brass case will spring back a bit after re-sizing and the jacketed bullet does not....also resulting in less neck tension and a loosening of your crimp. I use a heavy roll crimp with 296 and XTPs and never have had a problem with bullets jumping. Your load of 42.5 with a 300 gr XTP is at absolute max from Hodgdon and way over max from the Hornady manual(39.3)....is there a legitimate reason you want to push them so hard? I've found anything over 38.5 gr with a 300 gr XTP and I need to drive the cases outta my X-Frame's cylinder with a dowel and a hammer.

 

[Scrapper]

I began with new Starline brass, CCI magnum primer, and WW296 powder.
Started with 38 gr 296 in the 460 and ended at 42.5 grains.

I load the 460X 300XTP Mag at 35grains of W296 and Winchester Large Rifle primers, roll crimped with no problems. Like buck460XVR said....sounds like your just too hot.

I have a power tool to press a deeper channellure into the bullets. I can grind the belling insert to minimize expantion of the resized cases. Perhaps a different brand of brass might be stiffer. Lastly, I could roll a second channellure into the case and bullet. That would likely shorten case life to one or two loadings.

The power cannelure sounds interesting but may raise your pressures even more

 

[shovelwrench]

Post a picture of your crimp.

 

[Gun 4 Fun]

I think buck460XVR gave you your answer.
Starline brass is as good as it gets, so I would be extremely suprised if that had anything to do with it at all. The re-sizing of the brass and bullet upon seating definatey will. I would try a set of either Hornady or RCBS dies if at all possible, and see what happens. The expander plug should be at a minimum of .004" under nominal bullet diameter. Use a good roll crimp.

I don't have the .460, but I do have an F/A in .475 Linebaugh, and I use 35 grains of H-110 under a 325 grain BTB WFN GC @1600 fps across the Oehler 35P, in Starline brass (should be similar recoil levels, maybe even higher in the F/A due to it's lighter weight). I have no issues with crimp jump. I use the Hornady New Dimension dies, and have been completely happy with their performance, though I prefer RCBS dies as a rule. Either would be a step up in performance over what you have IMO.

 

[geomort]

Thanks for the advice. Maybe I over crimped them and got a loose fit from the brass spring back. I will experiment with a roll crimp too.

In general I'm a conservative reloader. My past experience with 296 in 44 mag loads taught me that cosistency in velocity is dependent on high load density and firm crimp. I worked up to the maximum load based on two observations. First the 460 and 454 cases were smoked at the lower loadings indicating low pressure not expanding the brass well. Secondly, the velocity varried over 100 fps at the lower loadings. For this batch of components 42.5 grains of 296 and CCI magnum large rifle primers is a consistant 1650 fps for the 300 grain XTP. With 454 loadings of 36 gr of 296, CCI magnum small rifle primers and the 250 grain XTP 1700 fps is obtained from the 5 inch barrel 460. Now to perfect the crimp.

The why. The 460 will go to Alaska for our Kayak and bicycle trips. Loading will probably be a 400 grain solid. We sleep on sand bars and roadside. Down south here, open country, the 454 and 200-250 grain is a better choice. Actually, the 329 is my preferred back country firearm. It is just marginal in Alaska and stout on recoil with full house 300 grain solids. Weight on the bicycle and afloat is not as great a consideration as when backpacking the high country. There is a noticable difference in preceived recoil firing 300 grain projecitles from a 460 compared to a 329. My wife won't shoot the 329 when it's loaded for bear. Fortunatly, bear generaly prefer women, so I will likely be doing the shooting.
She likes shooting the 460 but not carrying it.

 

[duckloads]

I've used 300gr Speer GDHP meant for 454 Casull with RCBS dies and 460 brass. Use what they call a neck-down crimp (I think). The case is flattened and forced into the bullet's crimp groove. In the crimp groove the brass case is the same diameter and the rest of the bullet. no worries.

I also use XTP bullets, but in much lighter loads. The above Speer bullet will fix your problem (I think).

That's about all the thinking I'll do.

 

[duckloads]

I hope you can see the neck down crimp in this photo

 

[geomort]

oversize expander

Well I think I found a big part of the problem. The expander die starts at .452 and goes quickly to .460 then a flare. Must be for loading soft lead bullets. It's a lot easier to mill some metal off the expander than add it on. I think I'll turn it down to .450 and see how that works. With my 45/70 loading I can see the bullet shape within the straight wall case. They don't jump crimp. That's what I'll make the 460 loads look like.

 

[Scrapper]

Sounds interesting let us know how it works.

 

[geomort]

turning the Lee Expander

Chucked up the expander in my drill press. Forget the file it's way to hard for that. Emery cloth worked it down a couple of thousanaths. Now it does not expand the brass that I can measure. After seating the bullet the case is .005 larger than before seating a bullet. Tried a roll crimp and a collet crimp.
Saturday at the range will be the test. My resize dies don't make the Starline brass small enough to get the bullet visible in the case look I had hoped for. Might have to try another brand of resizing die it the neck tension is not great enough to hold the bullet.

 

[Scrapper]

What kind of interference fit you figure you have for bullet tension?

 

[geomort]

rolled better than collet crimp

Tried both a heavy roll and collet crimp and pullet still jumped.
The roll held better than the collet crimp. I'll get out the mike and try and figure out what's going on. I think the resizing die is just not making the brass small enough. The brass is .005 larger after I seat a bullet. Will also contact the die manufacturer and get his input. Interesting solution to the problem with my 44 mag. See my post for details.

 

[Jellybean]

If it were mine I would try an asphalt sealant, if I could find something that was acceptable with no addatives that could hurt the barrel.

Or you could just glue them in place. With either you would want to rework your loads to make sure the pressures aren't going too high.