Inasmuch as loading manuals give data for cartridges that adhere to the normal cartridge overall length...for example 2.80" for .308 based calibers...is it reasonable to assume that if a particular rifle magazine and the chamber free bore, allow for a longer oal,can the powder charge be safely increased a bit to improve performance? I built a .350 Rem Mag on a Montana Rifleman 1999 short action with a 3+" magazine and I'm starting to develop loads. This is the first rifle that I have owned that allows a significant increase in oal over the factory spec.

quote:

allow for a longer oal,can the powder charge be safely increased a bit to improve performance?

yes and no

yes....at least in theory you should be able to

no.....you still work up watching for pressure signs....

The difference won't be noticed too much with lighter bullets.....but the longer ones might show a decided difference.

Start low on the powder charge and work up as always.Cartridges are listed to work at a set maximum PSI. As all guns are different, you may or may not be able to increase the powder charge above listed maximums. Going above a listed maximum in never a safe thing to do, unless you have very expensive testing equipment to monitor the pressures. A longer free bore than normal MAY reduce pressure. The Weatherby rife was/is known for its long free bore to reduce pressures.

I recently ran into this while reloading for a rem. 700 CDL SF in 257 weatherby. I started with book loads but was getting blow back on the cases. Book max is 69.5gr with Reloader 22, I slowly worked up until I noticed pressure signs (slight hard bolt lift at 75.5gr). Blow by stopped at 71gr, best accuracy was at 73gr.

You are looking at the problem from the wrong end. We can't reasonalby sit in a chair and determine how much of what powder we will use and adjust book loads accordingly.

The book makers tell us what they used for THEIR rifles but ours are different so our results will be different, for a LOT of reasons!

Pick the OAL you want to start from and develop your load. After that, vary the OAL each way, I prefer steps of 5 thou, until you find the best shooting length.

Also remember, just b/c your mag box allows bullets to be seated longer, the distance to the lands may not.
I always try to do my initial set-up based on the lands, not mag box length. Sometimes you have to shorten the col to fit the mag box, other times not. I do not think I have any cartridges loaded for A specific rifle loaded to "book" col. I don't do it to get more powder in the case, but to tailor "my" loads to "my" rifle.

There are so many variables that one must consider, and that's why we start at a known safe charge and work up slowly looking for pressure signs.

In another thread we talked about some rifles demonstrating pressure signs before the max charge, listed in the manuals, is reached. If you started with higher charges than stated for such, you might have dangerously high pressure. Under the conditions you mention, you might be able to use a little more than the max listed charge, but you could only safely arrive at that by starting lower and working up slowly, watching for pressure signs.

Dealing with what seems to be huge jumps to the rifling.


Very common in some factory rifles also. The only reason to jam a bullet into the leade/rifling is to center the round in the chamber. IMO. Unless a chamber is custom cut to fit your loaded cartridge AOL, your not going to benefit by seating into the leade/rifling. When possible, the bullets base, when seated, should be at the neck/shoulder junction of the case. There are other ways to center the cartridge in the chamber.1. Controling your shoulder bump. 2. Using bushing dies and only sizing part of the neck area. For bolt actions, a Lee collet neck sizing die would work also, when only sizing part of the neck area.

quote:

Originally posted by vapodog:

quote:

allow for a longer oal,can the powder charge be safely increased a bit to improve performance?

yes and no

yes....at least in theory you should be able to

no.....you still work up watching for pressure signs....

The difference won't be noticed too much with lighter bullets.....but the longer ones might show a decided difference.

I agree, just depends. Chamber spec, freebore also matter. You still have to work up the load, regardless of the book data.

I agree with vapodog and fred338. Alot of the OAL by SAAMI spec didn't have the longer type bullets like the accubond,tsx,vld etc so we have the manuals as one size fits all.

I had a 35 WhelenAI build wanting to shoot 225gr bullets. Using the OAL for the 35 Whelen @ 3.340" would work say for the 225gr Sierra bullet lenght of 1.150" and the 220gr Speer Hot-cor at 1.110". If I want to shoot the 225gr Accubond that bullet length is 2.370" and the TSX 225gr is 2.320" and I might wind up with some compress loads.

I opt for a OAL 3.500"

When I build my 284 if I was wanting to shoot a Speer 145 that bullet length is 1.165" the 139gr Hornady is 1.150" and the 120gr Nosler is 1.040".

I wanted to shoot 160gr Accubond @ 2.410" long and 160gr TSX at 2.400" so OAL for my 284 is 3.100" and that allowed me the opt of shooting Berger 180gr VLD bullets.

Myself I think at some point with the e-tip/tsx
and other longer type bullets might need two type spec for OAL. for some reason Hodgdon has over SAAMI spec pressure for the 280AI @ 62.1K psi and they been doing that the last few manuals.

Thank you all for the input. My MR1999 short action .350 Rem Mag has sufficient free bore that I can load most bullets to a 3" oal without making contact with the rifleing. With a 12" twist and a 3+" mag box, it should do well with heavy for caliber bullets.