OAL vs Pressure

[hardpan]

Guys, I believe that this is somewhat gun dependent, so I will start by stating that I am shooting WBYs for this question,

The question is how does C OverAll Length affect total pressure? I have not chronographed any of these, but I tend to load longer than the stated lengths in the book, and tend to use the size of the magazine as my limiter as opposed to touching the landings. This is because in WBYs , there is a ton of freebore (* at least another 1.8 of an inch from the magazine and more like 1/4" from the length in the book.

I am having a devil of a time getting my .300 WBY to shoot well. I am about 1-1.5 inches now at 100. But, it likes faster loads, and I am nearing the max now. (* using 180gr ABs).... I am also loading for 4 different .257s WBYs and 3 different 7mms. I have great loads to 2 of the 257s and 2 of the 7s.

thanks,
Hardpan

 

[nitis]

did you try seating them deeper?

go measure some factory ammo and see what you get

I also compared other manuals to the nosler book in regards to my 257 and they all call for mch deeper seating than the nosler book

back to your question I dont think you will hit any pressure issues since there is freebore you cant realistically hit the lands which could induce pressure

at least that makes sense to me the freebore sucks up the pressure right?

 

[CAhunter]

Hardpan What is the OAL you are using and what powder?? If you can't get it to group any tighter maybe a switch in powder would help you out. I know my brother 300wby has been very good with IMR 7828. Also most of the accurate loads were a OAL of 3.560. Good luck

 

[hardpan]

Hardpan What is the OAL you are using and what powder?? If you can't get it to group any tighter maybe a switch in powder would help you out. I know my brother 300wby has been very good with IMR 7828. Also most of the accurate loads were a OAL of 3.560. Good luck

I have seated them deeper, no real difference in results. Here is my "best" load for this rifle. (i use it in another .300 wby with good results, 1/2 inch groups) My rifle, at best is 1" and usually more like 1.25"

OAL: 3.69
Fed 215 primers
84 or 84.5 Gr IMR 7828

When I backed in down in steps to 82.5 grs, the group grows. And with that rifle, range time is tough as the guns heats up really fast.

Of course, maybe i cannot shoot that well anymore after needing glasses.

 

[Greg Nolan]

You might want to loose seat a bullet long and see exactly how far you are from the lands. The accubonds have a slower taper than many bullets and can be seated longer if you have the freebore and magazine length. Are these Mark Vs or Vanguards? My most accurate load for the 300 Wby is :
R/P brass 2.815 CL 180 gr Nos A/Bs CCI 250 primers 77 grs. IMR 4350 3.56 OAL 3143 FPS. That was in a WBY Vanguard and the same load was tops in a Winchester model 70 I used to own. SUB MOA in both.
One thing I noticed on the Vanguard is that it had a rough, heavy trigger pull and I changed to a Rifle Basix trigger and it helped a lot.
Good luck
Greg

 

[hardpan]

You might want to loose seat a bullet long and see exactly how far you are from the lands. The accubonds have a slower taper than many bullets and can be seated longer if you have the freebore and magazine length. Are these Mark Vs or Vanguards? My most accurate load for the 300 Wby is :
R/P brass 2.815 CL 180 gr Nos A/Bs CCI 250 primers 77 grs. IMR 4350 3.56 OAL 3143 FPS. That was in a WBY Vanguard and the same load was tops in a Winchester model 70 I used to own. SUB MOA in both.
One thing I noticed on the Vanguard is that it had a rough, heavy trigger pull and I changed to a Rifle Basix trigger and it helped a lot.
Good luck
Greg
_________

Hi Greg,
thanks. Right now, I cannot go very much longer and get the cartridge into the magazine. This rifle is a Mark V. Trigger has no creep and about a 2 lb pull, so I doubt that is the culprit. I have some 4350 so I can try your load. Appreciate the help!
Hardpan

 

[3006savage]

Seating the bullet out will generally reduce pressures and velocity provided you are not seating into the lands.

If you are considering going over the book max I would suggest using quickload to estimate pressure. You will need to input OAL, powder type and charge, etc.

Also chrony the loads as this is a great indicator of pressure. When your velocity is getting close to the max charge velocity in the manual you would know that you need to stop regardless if you see pressure signs.

 

[hardpan]

Thanks for the replies. I used 85 Grs of imr 7828 and the group tightened a 1/2 inch. Had 2 close and a flyer about 1 inch away for a total of a 1 inch group. Will CHrono next time out, and even push the bullet a bit faster... No signs of pressure at all, yet....
Hardpan