Tubby45

I for one, recommend the book titled "ABC's of Reloading" to anyone who reloads, veterans and beginners alike. It is a well written book and in my opinion, should be purchased and read cover to cover before any [major] equipment is bought.

The next thing that should be looked at, and is the focus of this thread, is the reloading data manuals. You can never have enough manuals. Read that last sentence again. Now, you will note that if you look up data for the same bullet with the same powder you will get different starting loads and different maximum loads.

The bullet and powder makers (hereafter "makers") test their data under different conditions than the next one. They also might use a different primer, different OAL (over all length), or bullet. Some makers use a generic FMJ while others list a specific brand. Some use a universal receiver and other makers use production firearms. This will be listed in the manual. Do NOT assume you can switch bullets and use the same powder charge as the previous one, even though the bullets are the same weight.

Any change in component can bring disastrous results. Drop down to the starting charge and work back up in .2gr increments.

Bullets have different lubricity, powder burn rates vary from lot to lot, primers vary lot to lot, cases have different capacities-heavier cases mean more material mean less burn cavity means less capacity. Always start out loading at the minimum charge and never exceed maximum charge. When you see pressure sign, back off and leave it. The max for the data listed will be different for your gun. You can have two identical guns, both will max out at different charges with the exact same components, etc.

Let's look at some examples:

Alliant data for the 10mm Auto with 155gr HP using Blue Dot powder:
1.25" OAL
5.5" bbl
Fed. 150 primer
Blue Dot 11.5gr MAX LOAD back off 10% to start per Alliant
1,340fps
34,100psi
from website

Hornady data for the 10mm Auto with 155gr XTP using Blue Dot powder:
1.26" OAL
5.5" bbl
Win WLP primer
Blue Dot 12.9gr MAX LOAD
1450fps
no pressure listed
from Hornady #7

Let's now compare the data from above. The bullets are the same weight, barrel length is the same, as is [obviously] the powder type.

The differences are OAL, primer type, and [obviously] powder charge. By lengthening the OAL to the SAAMI max for the 10mm Auto to 1.260" you create more space in the case which gives the powder more room to build pressure. The result of this is lower pressure.

Think of it as shaking up a full 20oz bottle of soda versus that same amount of soda in a 2L bottle. The smaller bottle will build more pressure than the 2L bottle. You can open the larger bottle and stay dry whereas if you open the smaller bottle you will have soda spraying all over as the pressure is released.

Also an exact bullet was used in the Hornady testing, the XTP, and the Alliant data listed a "HP". Generic bullet with that weight.

I have worked up data starting at 8.2gr and worked up to 12.5gr with the XTP, using a WLP primer, and OAL set at 1.260". I have no pressure sign, and I'm still under the max charge with .4gr to go before listed max. This load clocks 1399fps from my 4 inch 10mm 1911. That load is supposed to get that from a 5.5 inch barrel. Impressive, eh?

Notice the charge I use is over the Alliant data max charge. Also note the primer is different and my OAL is longer. This can have an effect on pressure. I can say with great confidence if I took a Fed 150 primer with my same charge of 12.5gr Blue Dot set a little shorter at 1.25" OAL I would have pressure sign, possibly rupture the case, and blow my gun up. Scary indeed.

Cross referencing data can be tricky but is highly recommended. When in doubt, use the most conservative data you have.

Arkhangel

Nice write up. Thanks for that info.

SY

P95Carry

Good info Tubby thx .. I endorse the ''ABC's" for anyone starting out - but would add to that the front section of Richard Lee's - "Modern Reloading'' second edition.

Also would impress on folks to never be tempted to max loads - work up ........ interestingly in many cases, loads a bit below max will often outperform max loads - in accuracy - plus ''tuning'' to a gun. Rifles in particular with this.

__________________
Chris - P95
NRA Certified Instructor & NRA Life Member.

"To own a gun and assume that you are armed
is like owning a piano and assuming that you are a musician!."

If a BG dies as the result of pointing a gun at me, then he has merely succumbed to an occupational hazard of being a thug

Tubby45

I reserve max loads, after working up, to hunting rounds only. I do work up to max with every bullet/powder combo in my gun and note it.

There are fundamentals of shooting that are more important to master than shooting a pattern of full house loads. They are fun to impress a chick but outside of hunting don't serve much of a purpose.

Every once in a while I'll load the 10mm to 235PF (180gr @ 1300fps 4"bbl) and shoot IDPA with them. Last year the muzzle blast knocked down one of the covers on the overhead lights above the shooting stall. Oops!

friesepferd

thanks.
and i agree, ABS of reloading is a great book!!!

edit: so YOU broke that light!

Tubby45

Seen that, eh? I was about two lanes down from that and everyone scattered behind me. Then I saw the light. People thought it was a howitzer. Nope, just a 10mm with full power loads.

Couldn't make it today. Had to shovel. Started at 7am finally got done at 630pm.

P95Carry

Geez ... - that sounds bad ... how much ''stuff'' did you get? You don't mention your actual location.

__________________
Chris - P95
NRA Certified Instructor & NRA Life Member.

"To own a gun and assume that you are armed
is like owning a piano and assuming that you are a musician!."

If a BG dies as the result of pointing a gun at me, then he has merely succumbed to an occupational hazard of being a thug

Joe R

Even for hunting ammo, full blown max loads are not necessary.

For hunting loads I'd rather shoot the heaviest for caliber bullet at say 80% of max MV than a lighter bullet at 100 or 105%.

mech1369dlw

That is 11 1/2 hours of shovelling, snow I would venture a guess on. I'm afraid I would have to get a blower or plow or a bunch of kids or something. Man, that is a lot of shovel time!

__________________
A person is justified in the use of deadly force, if such person reasonably believes deadly force is necessary to prevent imminent death or great bodily harm to such person or a third person.

Tubby45

P95Carry, I'm in Michigan's UP up by friedepferd, who is a member here. We are about a 20min drive away from each other. Haven't met yet. Would have today but we got dumped on.

It's been snowing for 9 days straight. Behind my truck I had about 4 feet thick (linear) snow and it went about chest high. Then by the sidewalk there was about 6 linear fet thick out to the road and it peaked over my head (5'-10"). The village plows the one sidewalk but I'm on a corner so the 50' of frontage is taken care of, save for the pile the plow makes doing the street and sidewalk. The 120' side of my lot is all up to me. It took me from 7am to 1130pm just to get the part by my truck done.

On the long side, my wife parks in the garage. There is about 12-15' of driveway before the garage and that was all drifted and plowed about chest high for the whole 12-15' from street to garage. I started that at about 1pm after a break and lunch. Took me til just before 630pm to get done. and I just did the driveway, not touching the sidewalk at all. There is no room to put it so it's staying.

Of course I get that done and my FIL drops off a snow blower I can use for the winter. Gee, thanks.

I'll take some pics tomorrow. Truly a sight to behold.

We got steady, heavy, wet snow the last four days. We got about 2 feet the first of those days and about another foot each day, so we are close to 5' or 60". Last year I think we got 294" from December to May. The week of St Patrick's day we got 39 inches in four hours. That was fun.