Is OAL Static? Pic Included

[Hardegg]

Once I deterimine correct OAL fro a rifle is that a constant or will it change wil differing powder charges?

I selected a powder charge from my last test and visited the range again to find best OAL
And got interesting results today. See pic.

All testing was at 300 yards off bags front and rear but no gun vise.

there is only 4 shots in the .010 spot because I kept the last round to use to help reset my dies. But I am going to use .008 off lands since the results were so scattered once I went to .015 I was really shocked at the sudden change.

The reason for my question is that through out todays test my velocity was lower my last trip.

I am happy with the grouping but I wanted to know out of the 2 factors that were differant, which one played biggest part. that would determine weather or not I increase my charge to get back to my desired FPS.

The bad thing is I really don't type well and this takes me forever.

Prior test had velocity at 2723. Today's test it was at 2668.
2 things were differant.
The temprature was 18 degrees colder from 80 to 62

And the brass was new on first trip this was same brass resized with full lenght dies but set to only bump the neck .002

Would that temp change give me a 55 FPS drop?

Starting to feel alittle Savage lovin. When I first got this gun all I had was some factory loaded "match" ammo and it shot so poor that I was wondering if I went wrong not going with Remmington.....
But with the handloads I am hitting a couple of combinations that really standout. It really seems sensitive to OAL more then anything. Maybe most guns are like this, I'm still new I used to only try to work up powder charge but now I have a couple of new tools
BTW can someone tell my how to add pic to the body of the message?

 

[rwilson452]

changes

Once I deterimine correct OAL fro a rifle is that a constant or will it change wil differing powder charges?


It should remain more or less static provided some other things don't change
I selected a powder charge from my last test and visited the range again to find best OAL
And got interesting results today. See pic.

All testing was at 300 yards off bags front and rear but no gun vise.

there is only 4 shots in the .010 spot because I kept the last round to use to help reset my dies. But I am going to use .008 off lands since the results were so scattered once I went to .015 I was really shocked at the sudden change.

The reason for my question is that through out todays test my velocity was lower my last trip.

I am happy with the grouping but I wanted to know out of the 2 factors that were differant, which one played biggest part. that would determine weather or not I increase my charge to get back to my desired FPS.

The bad thing is I really don't type well and this takes me forever.

Prior test had velocity at 2723. Today's test it was at 2668.
2 things were differant.
The temprature was 18 degrees colder from 80 to 62

With most powders that shouldn't make a difference unless you shooting really hot loads.

And the brass was new on first trip this was same brass resized with full lenght dies but set to only bump the neck .002


This could change things greatly. Even using a full length die the case is not the same as new.

Would that temp change give me a 55 FPS drop?

I think it's the case change. Try it again with those same cases full length resized. I suspect you will repeat the with the same Velocities. Remember only change one thing at a time. you changed two. Powder charge and new to used case. I would suggest you use the same OAL or the same powder charge the two will effect each other to an extent. altho oal will remain relatively constant unless you have a very large change in velocity or powder speed.

Starting to feel alittle Savage lovin. When I first got this gun all I had was some factory loaded "match" ammo and it shot so poor that I was wondering if I went wrong not going with Remmington.....
But with the handloads I am hitting a couple of combinations that really standout. It really seems sensitive to OAL more then anything. Maybe most guns are like this, I'm still new I used to only try to work up powder charge but now I have a couple of new tools

You didn't state what your rifle is chambered for.

 

[Lycanthrope]

I like to seat bullets close to the lands so, yes, OAL changes for me quite a bit based on the differing tapers bullets have.

With Hornady SST bullets, if I were to seat them out to close to the lands in my Model 70 I wouldn't be able to fit the min the magazine. With Nosler Ballistic Tips I can seat them out to bump the lands and still have them fit in the mag.

Based on the same bullets and differing powder charges.....the OAL stays put.

And....cold temps will slow bullets down due to powder and air density. Colder air is more dense and harder to cut. Fired brass is always different than new.

 

[Hardegg]

Wow your right I didn't post rifle info
It's a Savage 10FP-LE2B
Which is a 26" 308 bull barrel
with 1-10 twist

Loads are

175 gr Sierra MatchKings
44.0 Gr of RE-15
Federal 210M primers
Winchester brass

 

[rwilson452]

Load change

I would suggest you load up that same brass using the exact same proceedure you used the last time and see if it is consistant. If it is then begin tuning the load. ONE THING AT A TIME.

 

[Hardegg]

Roger that, I think 1 more session of just testing differant powder charges and I should be able to settle on a load.

I still have some new unfired brass and I will load some of those up with my same charge as before to see what the differance is there as well.