Ludwig Olson wrote an article in a 1950's American Rifleman article on the 6.5 Swedish cartridge and in it, he claims that a 140 grain bullet with 43.0 grains IMR 4350 is a service rifle equivalent. Accurate Arms told me that AA4350 was blended to the same pressure curve as IMR 4350, and it cost less, so I have been using that. And it shoots well in my 6.5 Swede's.
M1896 Infantry Rifle 29' barrel Carl Gustafs mfgr 1903
17-Aug-06 T = 85 °F
143 gr FMJ 1986 Swedish Ball
Ave Vel = 2610
Std Dev = 14.38
ES = 45.59
High = 2633
Low = 2587
N = 8
The longer barrel does make a difference as can be seen between the velocities of the same ammunition in a 29 inch barrel and a 24 inch barrel.
M38 Infantry Carbine 24" barrel
28-Oct-94 T ≈ 60 °F
143 gr 1986 Swedish Ball OAL 3.065" 47.4 grs powder average
Ave Vel = 2427
STD=22
ES = 62
Low = 2395
High = 2457
N = 10
The velocities I got out of my 22 barrel Swedes are faster by comparision, and that is probably due to a tighter tube. These are factory rifles, but I would not have chambered a barrel less than 24 inches long in 6.5 Swede. Your barrel is even shorter, and there is nothing you can really do to make up for that, and because of the age of your receiver, I am going to say it is unwise and unsafe to exceed service rifle pressures.
M700 22" Barrel
143 gr Swedish Ball 1986 headstamp
2 Feb 2008 T = 54 °F
Ave Vel =2470
Std Dev =18
ES =48
High =2491
Low =2443
N =5
140 gr Hornady Spire Point 43.0 grs AA4350 R-P new brass CCI-200 OAL 2.990"
2 Feb 2008 T = 52 °F
Ave Vel = 2512
Std Dev = 27
ES = 72
High = 2547
Low = 2475
N = 5
140 gr Hornady Spire Point (0.264") 43.0 grs AA4350 greased new R-P cases CCI 200 OAL 2.990" loaded 2-5-2000
2 Nov 2017 T=72 °F
Ave Vel =2531
Std Dev =14
ES =33
High =2540
Low =2507
N=5
140 gr Hornady SP greased 45.0 grs H4831 wtd lot 01-06-2014 new R-P cases CCI 200 OAL 3.065"
2 Nov 2017 T=72 °F
Ave Vel = 2419
Std Dev = 31
ES = 88
High = 2477
Low = 2389
N = 8
Shot an internet bragging sub MOA group with three shots. Too bad three shots proves absolutely nothing in terms of inherent accuracy:
I really think the four shot group is a better indication of the accuracy potential of this load, but, the fifth shot went out of the ten ring. This is proof that if you want to claim sub MOA accuracy, shoot as few shots as possible. This is something in-print gunwriters do all the time. Makes them and their loads look good.
Not in the middle, but a five shot group at 300 yards, 4.36 inches in diameter.
M70 Featherweight 22" Barrel
143.5 gr FMJBT Swedish 1986 ball. OAL 3.065" 47.4 grs powder average
13 Oct 2017 T=72 °F
Ave Vel = 2460
Std Dev = 21
ES = 30
High = 2474
Low = 2444
N = 5
Very good group
140 gr Hornady Spire Point greased
43.0 grs AA4350 R-P new brass CCI-200 OAL 2.990"
18 Nov 2007 T = 75 °F
Ave Vel =2428
Std Dev =29
ES =95
High =2480
Low =2385
N =24
easy bolt life,nice rounded primers
140 gr Hornady Spire Point (0.264") greased
43.0 grs AA4350 new R-P cases CCI 200 OAL 2.990" loaded 2-2000
13 Oct 2017 T=72 °F
Ave Vel = 2387
Std Dev = 23
ES = 67
High = 2424
Low = 2357
N = 15
Best group of all reloads
five shot group 200 yards
ten shot group, low, but 6.6 inches at 300 yards
this rifle did not Rem CorLokt's
For lightweight hunting rifles these groups are just fine. These are not 12 lb F Class rifles, and weight makes a huge difference in group size and recoil dynamics. These lightweight rifles are twitchy and extremely sensitive to variations in hold, trigger pull, front rest placement. Plus they move, requiring a re adjustment of position each shot.