260 speed issue

[kingkyle]

Hey guys,

Maybe you can shed some light. I have a brand new Tikka T3 sporter and with a 24" and I made some preliminary loads

139 Scenar
never fired Lapua Brass
BR2
H4831 , 45gr
2.80"

I'm avg 2500 fps. Is this even ball park? I see guys post that they are 2750 -2850. Is it the brand new brass? My 139's crunch a little when I seat... dont know if I can put more than .5gr inside. Any insight would be great.

super accurate with great groups but the speed troubles me.

Kyle

 

[AMG04]

Re: 260 speed issue

I would recommend trying H4350. You should see a velocity increase while maintaining the accuracy & consistency.

RE-17 yields the highest velocity in my rifle, but lacks some of the consistancy found with H4350.

With H4350 I would recommend starting at 41 grs and working up to around 43 grs. Right around 43 grs seems to be a common node in 260's (42.8 for my rifle).

 

[kingkyle]

Re: 260 speed issue

Thanks! If i can get a hold of it!

 

[RyeDaddy]

Re: 260 speed issue

42.7 grains of H4350 was best in my 260 with 140's.

As to your original question, I would think your velocity would be higher. I use 45.0 grains of H4831 in my 6.5x55 with an 18.5" barrel and get 2450 FPS with 140's, with the smaller case capacity of the 260 and almost 6" longer barrel you should be MUCH faster than mine.

 

[BillCh]

Re: 260 speed issue

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: I.D.F.A</div><div class="ubbcode-body">
139 Scenar
never fired Lapua Brass
BR2
H4831 , 45gr
2.80"
</div></div>

I plugged your general load information in to my interior ballistics calculations executable program (QL). The velocity prediction was 2760fps. I don't know what but something isn't right.

Might be time to try some H4350, RL-19, or something else. If you're stuck with H4831 you could try working up a load using a magnum primer but being that this is a Hodgdon 'Extreme' powder you still may not gain enough to get you where you want to go.

B

 

[badwolf]

Re: 260 speed issue

I chronoed my load of 43.0 grs H4350 at 2700ft, I added 1 gr to 44.0 grs and velocity went to 2915 ft avg for 4 shots ? 26" barrel

 

[kingkyle]

Re: 260 speed issue

Yeah I knew something was strange. I have small amounts of RL17 I think RL15 and varget. I'll try some "normal" loads with those powders and see.

I never know I could run a magnum primer, that might be awsome for me because I have 2000 mag primers and no use for them. Plus I cant sell them because shipping primers is not a good idea. If I try to use a mag primer, do I keep the 45gr or go lower?

 

[BoilerUP]

Re: 260 speed issue

Point of reference re: 4831SC and 260 Rem

45.0gr H4831SC
140gr A-Max
Lapua brass
CCI-200

2728fps from a 26" 1:8 barrel

Is your velocity data confirmed via actual dope, or simply chronograph readings? Your chrony could be off...

 

[Hondo64d]

Re: 260 speed issue

45gr gives me right at 2700 with 140gr VLDs from my 24" Brux.

John

 

[kingkyle]

Re: 260 speed issue

I'm thinking my chrono is off, my dope at 100 yards was exactly the same as a box of copper creek 139 factory loads. And my dope from 300 yds says the factory ammo was around 2750. Would my 100yd zero shift down if it was 250fps slower?

 

[Heman]

Re: 260 speed issue

Seems way slow. I get around 2740fps with 45gr 4831SC and a 142gr SMK. I know on a sunny day my chronograph gives me erronious readings. Why I quit using it, just find a load that shoots good, use Quickload to get a good ballpark and running those numbers in JBM usually gets my within 1MOA

 

[RobertB]

Re: 260 speed issue

Your shooting the exact load I shoot but I don't about the OAL. I just use my comparator and load right to the lands. I'm getting 2860fps out of my 28" Kreiger. Shoots great too. A lot people like the H4350 better but I had great luck with what I have so I haven't looked further. Good luck

EDIT: I use the SC. Don't know if it matters.

 

[Fester47]

Re: 260 speed issue

My load and seems to be close to everybodys sweet spot.
Krieger 25"
142 SMK .005 from Lands
Norma Brass
H4350 at 42.8gr
Fed210M
2815FPS