Bullet difference by 1 grain

MDS · October 21, 2010, 12:04 AM

You can use 125 grain data for 124 grain bullet.. yes? as long as they are the same style bullet.

fella5 · October 21, 2010, 12:40 AM

I don't see why not. As long as it is the same bullet type you should be fine. I'm working yup a load for a 6mm BR using 108gr Bergers... So I took data I could find for the 105gr and 107gr... Non moly or vld bullet.

THEZACHARIAS · October 21, 2010, 01:08 AM

Yup, no problem. I ran into that same problem using Hodgdons reloading data, and when I called their customer service number they told me to just use the 125gr data. You are also correct in regards to using the same type of bullet (using 125gr hollowpoint data for 124gr round nose is a bad idea, but I gather you knew or suspected as much before asking).

Lost Sheep · October 21, 2010, 01:54 AM

Quote:

Originally Posted by THEZACHARIAS

Yup, no problem. I ran into that same problem using Hodgdons reloading data, and when I called their customer service number they told me to just use the 125gr data. You are also correct in regards to using the same type of bullet (using 125gr hollowpoint data for 124gr round nose is a bad idea, but I gather you knew or suspected as much before asking).

OK, I'll risk asking. Why is using same-weight (or nearly same-weight) data for different construction bullets a bad idea?

I would opine that it has something to do with the amount of volume under the bullet (a hollow point generally expected to be longer than a solid shape like a round-nose) or the amount of bearing surface.

Or is it something else?

Lost Sheep

Is it really better to remain silent and be thought a fool than to open one's mouth and remove all doubt?

Thanks

Hey_Allen · October 21, 2010, 02:20 AM

I'm not an expert at this, but from what I've read in the discussions here and on other reloading forums, the difference is between the weight distribution in the bullet, how much of the bullet is contacting the bore (for instance, the much larger contact patch of a Barnes lead free bullet), as well as friction differences of different metals or coatings (lead, plated, jacketed, moly coated, etc...)

In an extreme situation, you could potentially have a load that pressure spikes due to higher friction, possibly enough to cause issues.

That being said, if following sane reloading practice and backing off the load whenever changing a component, any issues should show up before catastrophic events occur!

THEZACHARIAS · October 21, 2010, 04:22 AM

Quote:

OK, I'll risk asking. Why is using same-weight (or nearly same-weight) data for different construction bullets a bad idea?

I would opine that it has something to do with the amount of volume under the bullet (a hollow point generally expected to be longer than a solid shape like a round-nose) or the amount of bearing surface.

You are right about the volume of space below the bullet; using OAL length data for a different type of bullet could result in a projectile seated too deep, which would dangerously increase pressures. The same powder charge can be used with other same-weight bullets so long as you know the length of both and adjust OAL accordingly. Another variable would be using jacketed data for hard cast lead since they're typically one or two thousandths larger in diameter.

spacecoast · October 21, 2010, 07:46 AM

It's usually pretty safe to load a lighter bullet with a heavier bullet powder charge (within reason), 125 to 124 is a good bet, same with 100 to 95 or 150 to 148, etc. But be cautious on OAL to avoid creating higher pressures, as has been previously noted. Lead bullets also generally require a somewhat lighter powder charge than FMJ as well, plated bullets can run with a lead or with a low-level FMJ load.

**Unclenick** · October 21, 2010, 11:13 AM

Different bullet makers can have differences in jacket thickness and length, and those affect pressures, especially with small capacity cases like pistol cases. When you change brands, knock your favorite load down at least 5% and work back up watching for pressure signs and performance differences. If you changed bullet style or construction at the same weight, knock it down 10% and work back up.

1 grain difference out of 125 is not enough to matter from the standpoint of bullet weight. Many makes of bullets, especially less expensive ones, vary two or three grains from one bullet to the next all the time. Even cheap jacketed bullets can do that just because their lots are comprised of bullets that came off mixed sets of tooling.

MDS · October 21, 2010, 11:29 AM

Thank you all. I thought this was the case, but I don't think in taking chances. I double check things.

October 21, 2010, 12:04 AM	#1
MDS Senior Member Join Date: September 9, 2005 Location: Ohio Posts: 492	Bullet difference by 1 grain You can use 125 grain data for 124 grain bullet.. yes? as long as they are the same style bullet.

October 21, 2010, 12:40 AM	#2
fella5 Member Join Date: January 7, 2010 Location: Illinois Posts: 73	I don't see why not. As long as it is the same bullet type you should be fine. I'm working yup a load for a 6mm BR using 108gr Bergers... So I took data I could find for the 105gr and 107gr... Non moly or vld bullet. __________________ Scott

October 21, 2010, 11:13 AM	#8
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Different bullet makers can have differences in jacket thickness and length, and those affect pressures, especially with small capacity cases like pistol cases. When you change brands, knock your favorite load down at least 5% and work back up watching for pressure signs and performance differences. If you changed bullet style or construction at the same weight, knock it down 10% and work back up. 1 grain difference out of 125 is not enough to matter from the standpoint of bullet weight. Many makes of bullets, especially less expensive ones, vary two or three grains from one bullet to the next all the time. Even cheap jacketed bullets can do that just because their lots are comprised of bullets that came off mixed sets of tooling. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

October 21, 2010, 01:08 AM	#3
THEZACHARIAS Senior Member Join Date: January 26, 2009 Location: Louisiana Posts: 537	Yup, no problem. I ran into that same problem using Hodgdons reloading data, and when I called their customer service number they told me to just use the 125gr data. You are also correct in regards to using the same type of bullet (using 125gr hollowpoint data for 124gr round nose is a bad idea, but I gather you knew or suspected as much before asking).

October 21, 2010, 02:20 AM	#5
Hey_Allen Member Join Date: October 14, 2008 Location: NW Washington Posts: 39	I'm not an expert at this, but from what I've read in the discussions here and on other reloading forums, the difference is between the weight distribution in the bullet, how much of the bullet is contacting the bore (for instance, the much larger contact patch of a Barnes lead free bullet), as well as friction differences of different metals or coatings (lead, plated, jacketed, moly coated, etc...) In an extreme situation, you could potentially have a load that pressure spikes due to higher friction, possibly enough to cause issues. That being said, if following sane reloading practice and backing off the load whenever changing a component, any issues should show up before catastrophic events occur!

October 21, 2010, 07:46 AM	#7
spacecoast Senior Member Join Date: October 14, 2009 Location: Sunshine and Keystone States Posts: 4,461	It's usually pretty safe to load a lighter bullet with a heavier bullet powder charge (within reason), 125 to 124 is a good bet, same with 100 to 95 or 150 to 148, etc. But be cautious on OAL to avoid creating higher pressures, as has been previously noted. Lead bullets also generally require a somewhat lighter powder charge than FMJ as well, plated bullets can run with a lead or with a low-level FMJ load.

October 21, 2010, 11:29 AM	#9
MDS Senior Member Join Date: September 9, 2005 Location: Ohio Posts: 492	Thank you all. I thought this was the case, but I don't think in taking chances. I double check things.