mystery problem

[canuck4570]

I have a 450 marlin
the load is 29 gr 4759
the bullet is a 550 gr gaz check from mtn mold
fps is 1394 and no more than 5 fps deviation
at 100 yard its under 1 inche super accurate
past that the accuracy goes to the pot
8 to 10 inches at 200 yards
what could be the problem
this is the bullet in question
the rifle is a Steyr big bore bolt action rifle with 1/14 twist
http://i705.photobucket.com/albums/ww57/michelmongrain/IMG_0532.jpg

[excess650]

I suspect the nose profile is working against you.

[canuck4570]

I suspect the nose profile is working against you.
going to the range next week
will try a Saeco 540 gr with a more profile nose with the same load will see if its the nose

[MtGun44]

Have you run that boolit against the Greenhill formula??

http://www.z-hat.com/twistrate.htm

Check it out. Sounds like it is extremely marginally stabilized and goes off after 100yds.
Faster twist or shorter boolit, if that is the case. Check it out on the above link.

[Marlin Junky]

Speed it up and see what happens. It looks like it would be unstable at less than 1000 fps especially if it was launched by a 14" twist. A 550 grain .45 has the same SD as a 336 grain .35 and the boolit pic you posted looks mighty un-aerodynamic.

MJ

[canuck4570]

you got a good point
my friend shoots the same bullet at 1550 in his ruger no 1 in 458 and it is accurate
will try speeding it up
taking note of all the suggestions and will try them next week
thanks

[canuck4570]

Have you run that boolit against the Greenhill formula??

http://www.z-hat.com/twistrate.htm

Check it out. Sounds like it is extremely marginally stabilized and goes off after 100yds.
Faster twist or shorter boolit, if that is the case. Check it out on the above link.
took a look and yes its on the border line
and on JBM ballistic site its A OK ?

[HangFireW8]

Nice looking boolit.

And I thought I was silly casting Lee 310's for 444Marlin.

What is your alloy?

-HF

[canuck4570]

Nice looking boolit.

And I thought I was silly casting Lee 310's for 444Marlin.

What is your alloy?

-HF
wheel weight air cooled

[44man]

Twist is too slow for that boolit. Speed it up.

[canuck4570]

Twist is too slow for that boolit. Speed it up.
mmmm
its the same for the 458 winchester and this caliber shoot up to 600 gr bullets
1/14 twists.....
oops you are referring to bullet speed
will try to speed up the velocity

[omgb]

Speed it up. Your rate of twist is not well matched to the ballistic coefficient of that bullet. I bet dimes to donuts that 200 fps will make it stable out to 200 yards or more.

[canuck4570]

Speed it up. Your rate of twist is not well matched to the ballistic coefficient of that bullet. I bet dimes to donuts that 200 fps will make it stable out to 200 yards or more.
the BC is 230 and this is at 1550
will definitely speed it up to 1550 and up and see
and are you saying that I would need extra speed to go past 200 yards?

[omgb]

Yes, this is a fairly common problem in long range BP shooting. long heavy slugs require a fast rate of twist to remain stable as velocity drops off. A mere 200 fps sometimes makes a tack driver out of a tumbling scatter gun.

[canuck4570]

Yes, this is a fairly common problem in long range BP shooting. long heavy slugs require a fast rate of twist to remain stable as velocity drops off. A mere 200 fps sometimes makes a tack driver out of a tumbling scatter gun.
looking at all the quigley type rifle the are 1/18
and they shoot 550 bullet at 1000 yards
and my rifle is much faster 1/14 mmmm strange

[Echo]

And I will show my miserable understanding of aerodynamics by saying, It looks like it is a not very aerodynamic boolit, and probably goes transonic shortly after passing 100 yards, and is thus buffeted rudely around on the way to 200. Speeding it up will keep it supersonic to, and probably through, the 200 yard target.

[canuck4570]

And I will show my miserable understanding of aerodynamics by saying, It looks like it is a not very aerodynamic boolit, and probably goes transonic shortly after passing 100 yards, and is thus buffeted rudely around on the way to 200. Speeding it up will keep it supersonic to, and probably through, the 200 yard target.
I shoot a 30-06 whit a seaco 196 gr bullet
and yes I have notice that at 1200 fps it accurate at 100 yards and at 200 no good
slowed it down subsonic 1040 fps and it was then accurate at 200 yards could be the same here
will try cranking the speed and will try sub sonic all the way and see

[beagle]

Looks like a clone of the 462560 Lyman and I shoot them just fine in my M1895 Marlin. Of course, I've never shot any over 100 yards and the Marlin as well as I recall has a 1-20 twist. Same with my .458 X 2" with a 1-20 twist.

No stability problems in either.

Tweak it up a bit and see if you don't get better stability.

That's easy to say and may work but I've shot that bullet in a .458 Win Mag at 2200 FPS and it got my attention./beagle

[canuck4570]

speaking of 458 my friend has a ruger no1 in 458 and shoots my bullet at 2100 fps and no problem
that arrives at 200 well over the speed of sound so I am eager to see if cranking it up will do but one thing it will get my attention has you say....
by the way its a copy of http://www.competitor-pistol.com/jb%20home.html

[NSP64]

I vote for dropping down to subsonic from the start. If you bump it up to 1500 you still drop subsonic before 200yrds. I shoot a Lee 310gr in my SBH at 1100fps and it shoots fine. Plus at that speed I don't have to GC it.

[canuck4570]

I vote for dropping down to subsonic from the start. If you bump it up to 1500 you still drop subsonic before 200yrds. I shoot a Lee 310gr in my SBH at 1100fps and it shoots fine. Plus at that speed I don't have to GC it.
yes I need 1550 and up to be sonic at 200
will try both and see