450Bushmaster.net

Another 5 round string results are with 34gr lil gun all other specs from previous posts are the same average fps 2332 I'm going to do two more 5 round strings one with 33gr and one at 33.5gr
I'm personally wanting to get to 2150-2200 fps
Groups are still good in my world

I don't get it.....hornady tech told me to follow powder charges for 250gr FTX. I have duplicated factory rounds using lil gun @ 37gr C.O.A.L. @ 2.240" but while fooling with these 245gr SP #45204 I'm still in the "hot" zone. I'm gonna contact hornady again tomorrow and see if they will tell me recommended MAX velocities. I can't imagine that it would be anymore than the 250gr FTX. I've double and triple checked all of my equipment and recalibrated everything. Does anyone have thoughts?

I'd be slugging that barrel after giving it a total copper removal treatment. Brushing and patching alone does wonders for carbon removal but not so much for copper, especially when the barrel is new. It may just be cut a tad tighter than usual or have a lot of copper buildup. Either one can cause more pressure than usual but contributors to pressure don't stop there. If those 245's have a thicker jacket or harder copper blend or both, that can cause more than just their weight to contribute to pressure. When I say pressure, I parallel that with velocity as one tends to lead to the other, especially in this caliber. Forgive me for not reading the entire thread but have you mic'd some of those bullets with a mic capable of resolving .0001 and compared their average diameter with a similar number of 250 FTX bullets?

Late to the dance and just throwing ideas at the wall to see what sticks.

Hoot

Is there another chrono close by to verify?

who's barrel you running?

Hoot wrote:I'd be slugging that barrel after giving it a total copper removal treatment. Brushing and patching alone does wonders for carbon removal but not so much for copper, especially when the barrel is new. It may just be cut a tad tighter than usual or have a lot of copper buildup. Either one can cause more pressure than usual but contributors to pressure don't stop there. If those 245's have a thicker jacket or harder copper blend or both, that can cause more than just their weight to contribute to pressure. When I say pressure, I parallel that with velocity as one tends to lead to the other, especially in this caliber. Forgive me for not reading the entire thread but have you mic'd some of those bullets with a mic capable of resolving .0001 and compared their average diameter with a similar number of 250 FTX bullets?

Late to the dance and just throwing ideas at the wall to see what sticks.

Hoot

good insight as to construction/material differences.


are you aware of anyone thats cross-sectioned one of these like you did with the various FTX bullets in the past?

I know AR's can not compete with bolt guns as far as "hot loads" go but everyone and everywhere I've ever seen has had a sweet spot of LG in the 37-41gr range, including myself. That is of course loaded for accuracy, not speed. I finally got some load data that produces good results for accuracy so now I can chrono them with purpose.

I'm running BCA upper 1:24 twist. I know not top of the line. I live within my means for functionality. I do see posts on this forum from mid August 2019 on BCA. slugged barrel.within spec. Good copper scrub last night. Mic'd projectiles no noticeable discrepancies. Called hornady yesterday,absolutely no help other than saying that 245gr SP is "CAPABLE" of 3,000fps.whatever that's supposed to mean. Also said personally he would go with H110 or W296. I'm sticking with lil gun. I borrowed neighbors chronograph and will be running side by side tests hopefully later today.

Quite few have had good results with BCA 450B barrels. Some have issues but they get resolved.

3000fps? Not very useful info. I'm curious what the minimum expansion velocity is.

What is your bore diameter and bullet diameter?

Have you ran any factory ammo through the barrel? If so, was it also showing pressure signs?

Have you checked case head growth?

Did not check case head growth. 3000fps probably is "CAPABLE", do any manufacturer's make anything that will take that pressure? Doubtful! I've seen supposed reports of guy's pushing 2500fps with bolt guns, that's on them. So I ran side by side tests with two chronographs today. Caldwell and chrony alpha with lil gun @ 33.5gr. 2069.4fps and 2156fps respectively 5 shot string average. Then 33gr lil gun 2063.4 fps and 2139.4fps respectively 5 shot string average. Deviation chrono to chrono 76-86.6 fps. I'm not terribly concerned with that. Still holding 1"-1.5" groups at 100yrds. I'm going with 33.7-33.8gr of lil gun in my world and call it good. I will pick up a box of this factory stuff and chronograph some just for giggles. Thanks for everyone's thoughts and advice. I've been a BIG bore fan for years,450BM is a keeper! I'll post later on the findings of the factory loads.

kermit hunter wrote: 3000fps probably is "CAPABLE", do any manufacturer's make anything that will take that pressure? Doubtful! I've seen supposed reports of guy's pushing 2500fps with bolt guns, that's on them.

by capable im sure they mean "wont come apart" - not necessarily that it was a realistic velocity in the 450 bushmaster.

they might have used something like a Raptor to get there... which tends to run a bit hotter speed wise than the bushmaster does with similar bullets. i dont doubt a long barrel raptor loaded up WAY hot, would be able to get that extra 500 ish FPS needed to cross the 3000 fps mark.

or even a 460 S&W... match grade machine got the 250 ftx running 2597 fps in a 26" TC barrel (42gr lil gun, which doesnt seem off the ranch at all for what i can find online for this bullet in the 460) and just shy of 3000 with a 200 gr ftx factory load in 27" TC barrel. those are real world loads and not special hot-rods that us mere mortals couldnt load up and shoot in a production barrel.

either way im also quite sure that hornady's test barrels are quite a bit stouter than anything thats practical in the real world - if nothing else for safety reasons during new cartridge testing.

just my $0.02 anyway