450 problem

[bash]

Yet another newbie with his 450 today. I'm not new to reloading, but I am new to the 450 game. I figure someone here will be able to tell me what I'm doing wrong. Today I loaded up some (10) rounds for the first shots using hard cast bullets.

New Hornady cases 1.69"
Winchester small rifle primers
W296 Powder....32grns.
250 gr RNFP sized .452
OAL 2.04

I think this load is running around 1800 FPS

Here is the problem........

I pull back the bolt and let the first round slam in. Pull the trigger...BAM!
Pull the trigger again and ...click! No bang! Pull the charging handle back and it won't move! Take out the mag and tap the charging with a small piece of wood to move it just a little to "unstick" it. Pull the handle back and the round extracts. Out of ten rounds this happens 40% of the time. What am I doing wrong? What am I overlooking? I see nothing out of the ordinary looking at the expelled rounds.

Ideas?

Thanks,

Bash

[Hoot]

Did you lube the bullets?
Gas Checks?

I don't do cast boolits, but there are those here that do and I'm sure they will chime in.

Hoot

[Texas Sheepdawg]

I have heard some here are using cast bullets with some success, and I have been considering a cast bullet with gas checks, but just waiting to find the best solution.
Welcome to our electronic campfire!

[BD1]

I'm thinking that your boolits may be seated too deeply, (or possibly sized too large), and the heel of the boolit is causing a bulge in the side of the case. As the case has a slight taper, this bulge at the boolit heel is causing the case to wedge in the chamber, slightly short of being fully chambered. The "wedge anchor" effect. Lot's of discussion on this board about this problem which can also result from using the thicker .284 brass and jacketed bullets. Prior to using any load outside of the norms you need to pull off the upper, remove the bolt carrier, load a dummy to the desired COAL and drop the dummy into the chamber a few times to make sure that it will chamber properly and headspace against the lip at the front of the chamber. We call this the "thunk" test, so named for the sound you get when a properly assembled round drops in. No "Thunk" = Not good to go.

It is starting to sound like the more recent .450s may have tighter chambers than the earlier ones?

Three basic things I've learned about cast in the .450, (any AR platform really):
1. A good crimp is required as the sudden stop after the bolt slams the round into the chamber can cause the boolit to jump forward. The "body" type crimp works very well for this.
2. Gas checks are required. I am still waiting for a custom checkmaker from Pat Marlin which hopefully will produce a slightly taller check for the .450.
3. With properly assembled rounds, and adhering to #1 and #2 above, leading is a non issue.

What mold are you using?

BD

[wildcatter]

BD has the lead down pretty pat, so I too refer to his work.

I'm thinking that 32gr of 296 is way light and risks a Pressure Wave Event, better known as a Detonation. 296 carries a warning not to under load them and only has a 3% margin. I use 296 all the time, but I also sacrifice a case, by drilling a 1/4" hole through the flash hole, seat the intended bullet as normal and then fill the case with your powder of choice, in this case 296, and then empty into your scale pan for weighing. This will represent your max case capacity, for the given powder, not to be confused with max load. With max case capacity determined, then you can decide where your starting load must be and carefully work up from there, but you already know, from the previous work, where the compressed loads start..

..t

[Hoot]

BD has the lead down pretty pat, so I too refer to his work.

I'm thinking that 32gr of 296 is way light and risks a Pressure Wave Event, better known as a Detonation. 296 carries a warning not to under load them and only has a 3% margin. I use 296 all the time, but I also sacrifice a case, by drilling a 1/4" hole through the flash hole, seat the intended bullet as normal and then fill the case with your powder of choice, in this case 296, and then empty into your scale pan for weighing. This will represent your max case capacity, for the given powder, not to be confused with max load. With max case capacity determined, then you can decide where your starting load must be and carefully work up from there, but you already know, from the previous work, where the compressed loads start..

..t

Tim, you might want to elaborate on that one. If someone determines that their case with their bullet holds 50gr of 296. They probably don't want to start out with 50 - 3% = 48.5gr. No disrespect to you or the poster, but not everyone is thorough reader.

Hoot

[bash]

Well, here's what I have found. The boolits bulge the case slightly when I seat them but only on one side. I did the sharpie test and the loads seem too big. The bullets are sized .452, maybe I need to size them .451 Do I need to use a roll crimp and a taper crimp or just use the taper crimp? I also changed my OAL and I can now cycle them through the gun by hand. Maybe the crimp is the problem, maybe the boolit size is the provlem. BTW, 250gr boolit, with 32grns of W296 at 50 yards will peek through 1/4" steel plate and hit it like a red headed step child! Keep those ideas coming guys.....it helps!

Thanks,

Bash.

[Hoot]

Well, here's what I have found. The boolits bulge the case slightly when I seat them but only on one side. I did the sharpie test and the loads seem too big. The bullets are sized .452, maybe I need to size them .451 Do I need to use a roll crimp and a taper crimp or just use the taper crimp? I also changed my OAL and I can now cycle them through the gun by hand. Maybe the crimp is the problem, maybe the boolit size is the provlem. BTW, 250gr boolit, with 32grns of W296 at 50 yards will peek through 1/4" steel plate and hit it like a red headed step child! Keep those ideas coming guys.....it helps!

Thanks,

Bash.

Here's a tip for asymmetrical bulge. Start your sizing die in the press a few turns. Lube one of the asymmetrical cases and run it all the way up with the ram. Screw the die down until it encounters the case. Drop the ram a little and add a turn of the sizing die. Run it back up into the die. Retract and check symmetry. If not balanced, add another turn and repeat. As it gets closer to balanced, advance the sizing die in smaller increments. Shouldn't take much to center the bullet. Check the mouth diameter along the way and stop, even if still unbalanced if the mouth reaches .476 diameter. To maintain balance with all the loads in that run, lock the die down at the .476 point and use it instead of the taper crimp. I've substituted the sizing die in place of the taper crimp as an experiment and the accuracy was as good as if I used the taper crimp, though the bullet pull is a titch looser than if I had used the taper crimp die instead. They're both tapers, but the taper crimp acts more upon the end of the brass than the sizing die does. For obvious reasons, the sizing die acts at a shallower taper, further down along the body. Depending upon the degree of asymmetry, you can some times accomplish the same using the taper crimp die instead of the sizing die.

Otherwise, pull the bullets, discard them and resize the bulged cases and try again. I say to discard the bullets as they get resized just by seating them and they will not perform the same as ones that haven't been seated, or use them for fouling shot loads for barrel after cleaning. It's a fun experiment to compare similar loads using both the taper and the sizing die as your final crimp.

Hoot

[BD1]

Here's the short version of what I think I've learned about cast boolits in the .450B.

I think I'm seating my bullets out farther than a lot of guys. The first picture is of the three boolits I've worked with the most. The one on the left I designed specifically for my goal with the .450B, which is a 300 grainer at 2,000 fps. That boolit has the lube groove positioned to accept the body crimp with the cartridge at max practical OAL. The design in the middle is the lee 300 grainer, on the right is the Ranch Dog 350 grainer. I always establish my seating depth by dropping dummy rounds into the chamber, just as I've always done with 1911s. My goal is to seat them out as far as possible while still passing the "thunk" test, and staying under 2.260 COAL. I want that boolit centered as far into the throat as is practical when it gets the big kick in the rear. This has given me universally reliable feeding and better accuracy with all the designs I've tried. You'll notice that the 350 grainer is carrying all of it's excess weight out front, the heel is seated no deeper then the 300 grainers. I also size to .453, which fits my throat, but I may have a more generous throat and chamber than most. I'm using the Hornady brass for cast loads as it allows me to run the .453 boolits, and WC 297 powder, which is a surplus 30 carbine powder that's just a touch slower than 296.

I have a theory about cast boolits in the AR platform that revolves around the idea that the gas checks can occasionally be disrupted as they pass the gas port in the AR barrel. I can to this conclusion after seeing about 50% of my five shot groups with three shots touching and two outsiders. The second and third picture are a couple of groups shot while working up loads. Notice how the close group of three is consistent, but the two flyers can be all over the map. I have piles of targets that exhibit this with cast boolits, and virtually none with jacketed. I've been waiting a full year now for a guy named Pat Marlin out in California to make me a custom checkmaker that will produce checks slightly taller than the diameter of the gas port on the .450 to test this theory. Still waiting. In the meantime I'm interested in anyone's experiences with cast boolits in this cartridge.

BD

[Hoot]

Nice groups and I like the look of the one you designed the most. Is W297 too slow for 250gr .452 jacketed bullets? With those blunt noses, I'd bet you weren't too far from the lands, eh? The accuracy speaks for itself.

Hoot