Crimping too hard?

[Tripplebeards]

I get a flier every once in a while with about a 100 FPS lower velocity reading than average. My brass is all from the same lot, trimmed to exact lengths before every firing, loaded in a 450 bushmaster bolt rifle using a 35.5 grain load of h110 out of my rcbs chargemaster light that I calibrate before using every time, the lee 300 grain FN boolits WQ COWW with a BH of 16.5 used are weighed within one grain for consistency, using Remington 7 1/2 small rifle primers which are about the hottest flame thrower of a primer, tumble PC and Hornady GC. I’m taper crimping at .474” and pulled a dummy round I made this morning to see if it’s crushing my boolits. I’ve been getting good accuracy with them, a hair over MOA and then a flier once in about five to six rounds. I took my chrony out and discovered the fliers are about a 100 FPS slower. I did find I had a base screw finger loose. I had two scopes slide back and blame it on the loose base screw causing vibration. I has some other issues with the gun, trigger housing loose, and sent it in for warranty work. When I get it back Im going to bed the scope base with acraglass and spray some 3M 77 adhesive on my rings, and blue lock tite every thing down again and retest my load. I know an optic coming loose will cause my point of aim to shift down. Every time my scope slid back my boolit hit about 4/6” low. Could the vibrations cause the low velocity fliers as well?

Here’s a pic of my boolit I pulled. You can see the crimp line around it we’re I taper crimped it. I’m wondering if the little ring indent all the way around my boolit is OK or I’d I should lighten the taper crimp up to say .476”?




My crimped load at .474”, it feeds and functions flawlessly load a 2.055”

[upnorthwis]

Are you seating the boolit against the lands or giving them a running start? While I don't own a 450 Bushmaster, I would be using a roll crimp with H110.

[Tripplebeards]

Are you seating the boolit against the lands or giving them a running start? While I don't own a 450 Bushmaster, I would be using a roll crimp with H110.

It’s pretty common know fact that roll crimps won’t work with this caliber in bolt or semi autos. It’s a “taper only” specific cartridge. The cartridge head spaces off the case rim so it can’t be rolled in.

I did try a roll crimp just because I could and it jammed every time. The roll crimp flairs the neck out that’s causes all the issues. Just about everyone in the planet that loads these taper crimps them only. This article explains about it.

https://www.chuckhawks.com/450_bushmaster.html

[popper]

Haven't used that PC powder but it looks pretty scraped up, GC too - could be seating or pulling? Do you chamfer the mouth & flare? I've found that burnt carbon residue in the case will scratch up PC a bit but it does appear to increase boolit tension. Your taper crimp is like I use in 40SW, just s shiny ring at the mouth. What is the E.S. without the flyers? I don't use S.D., a S.D. of 10 gives a E.S. of 50 (normal dist.) so 100 fps may NOT be the real problem. Just a 100 slower should give vert. stringing if anything. Not flyers. If for example a string of 50 you get flyer every 5 or 6 shots repeatedly, it's bore condition. Otherwise it's boolit. You check case mouth ID and cast OD on each ? GC OK?, PC even? As for neck tension/crimp, fire some and check those in mag for length.

[flyingmonkey35]

For a boolit that has been fired it looks good enough to reload and shoot it again.

I think your on to something with the scope.

Sent from my SM-G960U using Tapatalk

[Tripplebeards]

Guys, I posted I made a dummy round and pulled it out with my boolit puller to see if the crimp cut into the boolit.lol

The boolit was never fired...just pulled from an empty case after crimping to test the crimp. I Seated it into an empty casing, crimped it to .474” and pulled it. The case was pin tumbled for 4 hours and clean as whistleinside and no powder added for this test...dummy round. My boolit puller has residual black powder build up so when the boolit hits the bottom of the puller it scrapes along the way picking up black powder. The GC was also scratched up from the boolit being pulled out.

The loaded boolit dose have dings in it from being tumble coated.pretty common to everyone that tumble PC boolits.

All my boolits have been sized to .452” after pc and the GC is installed at the same time.

Popper, the 100 FPS slower boolit loads drop about a good 4” perfectly vertical.

[megasupermagnum]

Is there any reason you can't try a magnum primer?

[Tripplebeards]

I would think I could. I never paid attention if someone manufactures magnum small rifle primes before. I do use magnum large rifle and pistol primers.

[sw282]

A small piece of foam in an inertia boolit puller will usually stop boolit point/head deformation

[sutherpride59]

I don’t know Jack about the cartridge but you always try a little Dacron filler.

[Conditor22]

I would think I could. I never paid attention if someone manufactures magnum small rifle primes before. I do use magnum large rifle and pistol primers.

CCI 450 small rifle magnum primer

CCI 34 might work also