Reloaders with AI MKIII's ??

[cramey74]

I have an AIAE MKIII that shoots fantastic. I have been loading for it since it was new with the following- Black-hills & Federal match brass, 168/175 SMK's, 44.5gr Varget, CCI BR2 primer. I have been loading to 2.800 OAL and this has worked for every .308 I have owned thus far. I recently changed my brass to Lapua & I am going to start fine tuning for this rifle. I used a Hornady OAL gauge and discovered my chamber is quite a bit longer than anything else I have owned. I loaded some 168's last night to an OAL of 2.835 and that still puts me .020 off the lands. I guess my question is, am I going to have a lack of pressure loading them that long? Also what are some of you using as far as OAL? I still have plenty of room in the mag to go longer, I just don't want to lose a bunch of velocity. I am currently getting 2700fps out of my 168's. Any help is appreciated

Chris R

 

[Defusion]

The smk's dont mind a bit of jump, so I wouldn't worry about that.
The 155 scenars I'm using do like to be loaded a bit longer. At 2,86" right now, which is about the max that will reliably feed from the magazine, but most consistent results were around 2,88/2,89
For my short-range indoor load I'm at 38,0gr of VV N140. Long range load OCW results say 45,2gr, but haven't chrono'd it, or actually shot it at a decent distance yet.
Lapua brass as well. It's just as expensive as anything US made, and generally regarded the best.

This is with the 20" LW barrel, and it's my first centerfire bolt gun, so can't really compare it to anything.

 

[Rprecision]

COAL is not going to change your velocity

 

[Defusion]

Oh yeah, if you do load them really close or into to the lands, you could get a pressure spike. So adjust/test loads accordingly.

 

[Bradu]

I'm loading 44 grains of Varget with 175smk and with the 155 scenar, both are loaded to 2.81 oal and shoot great.

 

[Temp9]

COAL is not going to change your velocity

Actually, it will. A jammed bullet will increase pressures resulting in higher velocities for the same powder charge. Similarly, seating your bullet deeper will decrease the initial expansion chamber, which will, of course increase pressures slightly, resulting in higher velocities. The latter scenario is pretty insignificant, though, depending on how much you change the COAL. If you increase your COAL, you can increase the powder charge slightly to compensate.

 

[cramey74]

Actually, it will. A jammed bullet will increase pressures resulting in higher velocities for the same powder charge. Similarly, seating your bullet deeper will decrease the initial expansion chamber, which will, of course increase pressures slightly, resulting in higher velocities. The latter scenario is pretty insignificant, though, depending on how much you change the COAL. If you increase your COAL, you can increase the powder charge slightly to compensate.

This was my initial thought. I kind of relate everything to racing, and to my thinking, seating the bullet longer/deeper would be like having less compression or more chamber volume. I went from 2.800 OAL to 2.835. I don't know how significant that is.

 

[Temp9]

A QuickLoad sim shows a 15fps loss by changing the seating depth from 2.800" to 2.835". Great program, by the way. I'd highly recommend purchasing it if you have the money.

 

[Beefman]

The 1st and only load I have shot in my MKIII is 44.6 Varget under 178 Amax. OAL 2.8115 It shoots good, but I'll have to try for better.

 

[mark5pt56]

OCW procedure. AEIII with some IMR4064/FGMM primer/FC case/175SMK, 2.8". I did go on another test up to 45.9, although accurate, had a tad bolt lift, not much and was over 2800fps.

Ok, shot on two different days. The first is after I went back and tried the lower charges and second one when I tweaked charge weights between first ones.

Although some shooting errors are present, what do you think?

I didn't chrono the second batch.

I appreciate the help

Mark

 

[cramey74]

OCW procedure. AEIII with some IMR4064/FGMM primer/FC case/175SMK, 2.8". I did go on another test up to 45.9, although accurate, had a tad bolt lift, not much and was over 2800fps.

Ok, shot on two different days. The first is after I went back and tried the lower charges and second one when I tweaked charge weights between first ones.



Although some shooting errors are present, what do you think?

I didn't chrono the second batch.

I appreciate the help

Mark

I have had similar results with about everything I have tried both factory and handloads. I have used BlackHills 168/175 and FGMM 168/175 with good results. My handloads have also proven to be very accurate. I was just thinking that locating the projectile closer to the rifling would tighten groups even further. The chamber is just really deep when compared to my other rifles, 2.860 vs 2.805 on say my Crusader. .055" seems like a big gap to jump, but maybe I'm wrong. If it doesn't yield anything I will go back to my original load.

 

[tnichols]

The SMK's seem very forgiving to jump based on their tagent ogive. I've got an ol' Savage 10FP where I'm jumping .042 with SMK's and it shoots real fine. If it shoots good, I don't care if their jumping the Grand Canyon

 

[Target In Sight]

155gr Lapua Senar, 45.5gr Varget, Lapua brass, CCi BR2, jump 0.020, and shoots right where the gun is pointed~

 

[Rprecision]

Actually, it will. A jammed bullet will increase pressures resulting in higher velocities for the same powder charge. Similarly, seating your bullet deeper will decrease the initial expansion chamber, which will, of course increase pressures slightly, resulting in higher velocities. The latter scenario is pretty insignificant, though, depending on how much you change the COAL. If you increase your COAL, you can increase the powder charge slightly to compensate.

A QuickLoad sim shows a 15fps loss by changing the seating depth from 2.800" to 2.835". Great program, by the way. I'd highly recommend purchasing it if you have the money.

I don't know how significant that is.

Its not! I have never been able to measure a differance clocked over a chronograph. While maybe 25 fps is possible, when you factor in the error built into the chronograph its pretty hard to quantify. In the relm of everything there are much bigger varriables to get worked up over then COAL vs. Velocity, maybe your milage may vary............

Now COAL vs accuracy, yeah there is something to be said there. Its been my expirence that they are all a little differant. Some dont mind jump, some do. For my intended use I want the COAL to work out of a magizine and also function in more then one rifle. As such, I usually stick to the 2.800 to 2.810 size

 

[cramey74]

Its not! I have never been able to measure a differance clocked over a chronograph. While maybe 25 fps is possible, when you factor in the error built into the chronograph its pretty hard to quantify. In the relm of everything there are much bigger varriables to get worked up over then COAL vs. Velocity, maybe your milage may vary............

Now COAL vs accuracy, yeah there is something to be said there. Its been my expirence that they are all a little differant. Some dont mind jump, some do. For my intended use I want the COAL to work out of a magizine and also function in more then one rifle. As such, I usually stick to the 2.800 to 2.810 size

I'm not getting worked up. I just want to explore this rifles potential a little bit. Like I said the rifle already shoots with anything I have owned. If it does not change it for the better I will put it back like it was. None of my other rifles have that much gap so I figure I would give this one the same advantage.

 

[Rprecision]

I'm not getting worked up. I just want to explore this rifles potential a little bit. Like I said the rifle already shoots with anything I have owned. If it does not change it for the better I will put it back like it was. None of my other rifles have that much gap so I figure I would give this one the same advantage.

Sometimes I have the tendency to come across pissing on others fires. That was not my intent and was attempting to convey my own findings.

For what's its worth I have a similar rig and if you search by me you will find my OCW test posted on here. Hopefully it may help as I have found others with the same results

Good luck

 

[hypno02]

I load 155 scenars and 155 Amax's to 2.868" (not sure how far from lands) in front of 47gr varget. Both loads shoot great in the 1-12" LW barrel with no pressure signs. I have utter confidence in the AI action holding up to an even hotter load. Buuuuuut I'm quite content with the scenar load I have now. Which, during load development, was right around .25moa through 18 shots and 3 different powder charges.

Hell, you could probably shoot some .243 core lokt through a .308 AI and still be sub moa.

 

[Bradu]

Damn, the primers are flattened at 45 grains of varget and 155 scenars in my AI