Bullet jump and mag length, which way?

[Lefty Trigger]

I had an awesome load for my 308 that was shooting Hornady 178gr A-max bullets. I loaded these to a 2.830 COAL (.032 jump) and they still fit in a magazine and this load would shoot about 1 inch at 300yds. Now heres my problem,.. I just shot the last of the A-max bullets I had. I ordered in over 600 of the 178gr HPBT Match bullets to replace them with and my load still shoots them good and the velocity barely changed but the bullet jump at mag length (2.830) is .084. with them and the group has opened up. Should I run them longer and single feed them? I also bet running them longer will require the load to be increased slightly. What do you think?

 

[marchboom]

Guess it all depends on what you're using the rounds for. If target shooting I would single-load them. If hunting, determine if the larger group is acceptable and load them in the mag. Never could figure out why rifle makers made mags shorter than the chambers.

 

[Bc'z]

I have the same issue in 2 of our rifles.
My 6five and mama's 260.
Mine are dialed at mag length, but the wife's I find shoot better seated a lil bit deeper.
Look at styles of bullets, I believe a tangent ogive will get you closer to the lands when dealing with mag length.

 

[Lefty Trigger]

I have the same issue in 2 of our rifles.
My 6five and mama's 260.
Mine are dialed at mag length, but the wife's I find shoot better seated a lil bit deeper.
Look at styles of bullets, I believe a tangent ogive will get you closer to the lands when dealing with mag length.

So in a nut shell no VLD style of bullet if mag feeding? The A-Max clearly "looks" a little fatter while the HPBT has a longer nose.

 

[Bc'z]

So in a nut shell no VLD style of bullet if mag feeding? The A-Max clearly "looks" a little fatter while the HPBT has a longer nose.

Not entirely, you can still shoot vld's but you will probably be giving up some horsepower as bullet is deeper in the case.
You can also look at a magazine upgrade to accommodate longer coal, or the most expensive route I'm guessing is a set back of the barrel I lil bit.

 

[mikecr]

I had an awesome load for my 308 that was shooting Hornady 178gr A-max bullets.

Then do that again, or start over from scratch.
Everything begins and ends with a bullet.

 

[Bc'z]

IME, a bullet deeper in the case means more pressure, hence more velocity (horsepower).

I stand corrected.
I should have said less powder capacity.

 

[Lefty Trigger]

Then do that again, or start over from scratch.
Everything begins and ends with a bullet.

Yep gonna have to as playing around with the load has only made things worse. I did find out I can get .050 more length and still fit the mag at 2.880 COAL. Didn't help though....

 

[mike06]

Yep gonna have to as playing around with the load has only made things worse. I did find out I can get .050 more length and still fit the mag at 2.880 COAL. Didn't help though....

Lefty what is your barrel length? I just switched to ArComp and I am get real good results with it and the Nosler 168 & 175 RDF's in 3 different 308 rifles. 20" Ruger Precision 1-10 , 24"Rem 700 Milspec 5r Gen 2 1-11.25 and my old Rem 700 VSSF 1-12 twist. 25" Also letting them jump .030 to .075

 

[Lefty Trigger]

1:10 twist 28 inch Douglass barrel, Savage 12. My load that was shooting awesome was using Hornady's 178gr A-Max bullet and using 42.3 grain of Norma 203B powder loaded at 2.830 length which gave a .032 jump with that bullet. Shot this group last Thursday at our 300 yard practice, 5 shots under and inch and was able to do this several times. Now today at the 300 yard match it shot so bad I had to switch out guns and try my 6mmBR which did poorly as well but that's another story.
I wonder if the Hornady 178gr ELD-Match would have been a better match to the A-Max instead of the HPBT Match that I bought??

 

[klamathsteel]

I'm shooting the ELD-M in my 300 WM and they are really good ! I believe the ELD-M is what replaced the A MAX.