Short OAL 9 major loads

[racer-x]

I started working up some short OAL major loads over the weekend and have been pleasantly surprised with the results so far.

No excessive pressure signs with any of my loads, and very consistent velocities around my 170PF target.   

Curious what experiences others have had loading with this constraint (OAL 1.100 - 1.125) ?

 

barrel= KKM 5.5", 3 holes, CK 3-chamber comp

bullet= MG124JHP

OAL= 1.120"

6.7 gr WAC 1381 fps, 9 ES  (171.2 PF)

8.5 gr 3N38 1379 fps, 8 ES (171.0 PF)

[Hi-Power Jack]

I usually load WAC / 124 gr MG JHP to 1.16", but used to load to 1.145" which worked just as well.

 

I'd be hesitant to load down to 1.12" - is there a reason you're doing that?

 

I'd ream the throat for longer seating before I'd load down to 1.12".

 

How was accuracy, by the way?   

[racer-x]

Reaming the throat was my first choice as well... no luck with that so far though.

More details here:

I shot groups at 50 yards today setting scope zero. Accuracy is good with 3/4" groups @ 50 yards when the wind let me do my part (3n38 load).

 

Both loads were very workable with only minor differences in feel.

Dot jumps more with the WAC load but is still very predictable.

3N38 load was flatter with a softer recoil impulse in hand (also louder). 

 

Inspecting brass again today and all is still looking good. Primers don't look any worse than my 1.165 OAL major loads did out of my old gun (same bullet, powder & PF).

 

 

[Hi-Power Jack]

If I contacted the rifling at 1.14", I'd load to 1.135" - bit better than 1.12".   

[racer-x]

I need more cushion in my target OAL to account for higher OAL variations in reloading mixed brass and using a compressed load.

 

If I seat a bullet with no powder in my 1050 set up for 1.120 OAL and 3N38, the OAL will be around 1.090. 

In normal operation, the bullet seating compresses the powder and when the die lifts away, the bullet rebounds .030-.040 to around 1.120.

 

I loaded 500 rounds of this 3N38 load last night and measured variations from 1.118 to 1.132. Even with this variation in OAL, ES over the chrono is still single digit.

 

On the short OAL topic, it is interesting to note how much less powder is required to get similar velocity with the shorter OAL loads - different case volumes.

While not a good apples to apples comparison with identical barrels, here is my load data for the same bullet & powder in different configurations:

 

Bullet: MG124-JHP
Powder: 3N38
OAL   charge    velocity    barrel
1.120   8.5gr      1375       KKM 5.5", 3 holes, 3 chamber comp, PVD
1.195   9.6gr      1374       S2 Trubor, 4 chamber, IonBond
1.250   10.1gr    1377       Schuemann, 3 hole hybrid, 4 chamber comp (38SC)

[BeerBaron]

I don't see a problem. As long as they feed and eject nicely. 

[jcc7x7]

IF it runs in the gun and chrono's !!! life is good!

[racer-x]

Agreed.

 

I put 500 rounds down range through this gun today on the clock with zero malfunctions. Split evenly between my short 171PF 3N38 and WAC loads.

Loving how the new gun shoots and tracks. Another surprise is that I like how the WAC load tracks best. The 3N38 load is producing a lot of gas and you can feel it in your face; dot seems to dip and I'm not tracking it as well. VV load 'feels' flatter, but I shot faster hits with the WAC over and over. Dot is just there.

 

How often is the less expensive and easier (to load) ANYTHING best ?

 

[9x45]

124 Bayous on top of 4.8 grains of TiteGroup at 1.100". Goes about 1,350.

[racer-x]

Got my short OAL 115 load dialed in today. Primers look good too.

 

Bullet: MG115-JHP
Powder: WAC
OAL   charge    velocity    barrel
1.120   7.3gr      1494       KKM 5.5", 3 holes, 3 chamber comp, PVD
1.165   8.1gr      1499       S2 Trubor, 4 chamber, IonBond

[racer-x]

Interesting comparison of brass between 115 & 124 loads at different PF's.

Not a big difference, but the brass from the 124 gr bullet loads are showing a little more primer flattening.

 

Guess I was expecting the 115 load brass to show slightly higher pressures signs due to higher charges & velocities...

May be the .020 shorter height 115's and increased case volume along with the 115's having slightly less mass to overcome.

 

barrel= KKM 5.5", 3 holes, CK 3-chamber comp

OAL= 1.130 - 1.135

MG124JHP 6.65 gr WAC 170 PF

MG124JHP 6.95 gr WAC 175 PF

MG124JHP 7.20 gr WAC 170 PF

MG124JHP 7.50 gr WAC 175 PF

 

I'm leaning towards the 115's for how the dot tracks right now, but it's really a very subtle difference. I've run a bunch of drills with each and the HF just comes down to my performance on that run. 

 

Shooting this gun in it's 1st match in the morning and will alternate loads between stages to get a more real-world feel for any differences in stage performance.

[racer-x]

115's are my pick for now. 

Still subtle differences between the two sizes, but the dot tracking seemed most predictable and was just 'there'.