.260 AI - Think I have got a load!!!!

B

bradtothebone

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49.7gr of H4831SC with a 139gr Lapua pill. Norma brass with 210M primer.

Have had fairly good results the higher I have gone, maxed out at 50.3 gr, but 49.7gr performs.

Will chrono the load later, as I don't normally chrono until I have a load I am happy with, I don't want to be skewed by speed. I have had this load on numerous occasions be fairly consistant, when I do my part. CGN member(s) were present during the first trial of this load, fairly similar results. (Sherwood Park Range by Tofield).... Now off to spark it up at distance.

.260AI Stiller Action from Corlanes, ATRS DM bottom metal, Rock 1:8 22" bbl, Macmillan HTG stock, jewell trigger, 20MOA rail, 5.5x22x56mm NXS scope. Gunsmithing by ATRS.

Had an issue with the Stiller Action, seems when Stiller was drilling the hole in the bolt it looked like it touched the chuck. Made a mess out of the primers.... Special thanks to Rod at RMR for machining it out, even though Stiller wasn't interested in fixing this flaw.

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Would be the rifle at the bottom..........


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Thanks all!!

If conditions (mosquitos whoooo boy there are tons) permit, I'll try to stretch its legs this weekend. I'll also chrono it.

During testing I have had multiple targets that produce results like this. The guy behind can't keep it together though....

What I have started to do it set up 2 targets and the back target gets set up every time I shoot this load, (same distance etc) and I will see how many rounds I get through it (say 50 or whatever) nd I will see what the group size is, I think this would be a good indicator of machine AND man behind the machine.......

:ar15:

Jerry...... Well OK valley will have to wait, things haven't even worked out for a visit either....... Dang work getting in the way again. Seems like it never ends ( could be worse though..... I'm really not complaining...... I made it to Banff for 4 days.... Thats about it for time to do anything....And I only made it cause it rained so much in edmonton I left while my contractors were waiting to dry it up....



Now...... Time for another build........ But WHAT???? Oh yes..... the gears are turning.
 
I'd love to butttttt

I have contractors coming tomorrow for concrete, and am removing sidewalks etc.

I am imagine its terrible, heavy spray..... I'm gonna try to get out this weekend though...

I'll let ya know how it rolls.
 
DrawBlood said:
I wouldn't care if it was 3'2" low...that can be fixed...that load can't get any better!
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Yeah...???!!! I guess I need to explain myself.....the "hahahaha" means a whole lot of sarcasm. I do realize that all it takes to make the point of impact change is 1/4 click up and 1/4 click left......anyways.

Can't wait to see some picks a distance Brad.
 
s.a.w gunner said:
I was using 48.0 grns of 4831sc on my 260ai and the primers were falling out after 3 to 4 reloads.49 plus must be crazy pressures.
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In a standard 260 Rem, 48.0 grs would be something like 65K psi, but in a 260 AI it would be a high end load, but still at a reasonable pressure (~55K psi). If your gun, your barrel and your brass has loose primers after 3-4 reloads with 48.0 grs though, it is a top end load for your gun.
 
s.a.w gunner said:
I was using 48.0 grns of 4831sc on my 260ai and the primers were falling out after 3 to 4 reloads.49 plus must be crazy pressures.
Click to expand...

Different barrels, chamber dimensions/throat length, bullets and even lots of powder/primer can make one load look hellishly hot but work just fine. There are so many things that can affect a load and 1 gr is not alot of difference in this volume of case.

I have shot a number of these 260imp/6.5 Mystics and my loads have always favored 48ish gr of my lot of H4831SC/primer, case, and bullet. I have used the same lots for a couple of years now so performance has been steady.

I have only had one barrel that would digest 49gr of this same lot of H4831SC and shoot well.

I now have a barrel that will only digest 46gr of the same components.

Just feed the rifle what it needs and wants.

Jerry
 
Powder weights

My testing was also over 50, infact 50.3 at the top end, I don't have flattened primers, hard bolt lift. 50 gr performed well alos, but 49.7 seems to be the ticket..... I'm pretty much maxed out with the 139 scenar for capacity, in fact its quite a compressed load, I put the powder in with a drop tube and slowly press the bullet in, a few crunches can be heard tho.....


I started out in the 48gr range for fire forming, and the speeds were about 2711 or so... I previosuly had a few run though the chrony just to see and i was about 2900 with the 49.7 gr, dont know if i burning all the powder or not with a 22 inch bbl... but it shoots good.!!!!:D
 
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