Speer manual - What is a DNR (do not reduce) load?

DaveInPA · April 13, 2008, 09:29 PM

Looking at the 9mm data in my speer manual for the 147gr speer gold dot JHP, the load data for Titegroup is confusing me. It has a minimum load of 3.3gr and says DNR (do not reduce). I'm assuming this means do not go below, 3.3gr which is all well and good. But this is where it gets confusing. There is NO max charge listed. What is going on here?

CPTMurdoc30 · April 13, 2008, 09:35 PM

I believe they are saying that is the only safe load to use. It is the min and the max.

To reduced below that would cause a Kaboom and going over that load would also cause a kaboom.

If you use a charge that is to light it may cause an extreamly high pressure spike too soon and cause your gun to become a part of your face.

DaveInPA · April 13, 2008, 09:38 PM

Well then, I won't be using Titegroup for that bullet. Thanks!

HankB · April 13, 2008, 10:19 PM

Quote:

I believe they are saying that is the only safe load to use. It is the min and the max.

To reduced below that would cause a Kaboom and going over that load would also cause a kaboom.

If you use a charge that is to light it may cause an extreamly high pressure spike too soon and cause your gun to become a part of your face.

While reduced charges in bottleneck rifle cases HAVE been documented to produce high pressure spikes, there's no credible evidence that small charges in straight wall pistol cases (or even slightly tapered like 9mm P) will do so - there just isn't enough chemical energy present.

Most likely, going below the recommended minimum will cause erratic results and excessive extreme spread . . . in a worst-case scenario, it might even stick a bullet in the bore.

FWIW, Hodgdon shows the following data with a 147:

147 GR. HDY XTP
Hodgdon Titegroup .355" 1.100" OAL
Starting Load 3.2gr 855ft/sec 22,500 CUP
Maximum Load 3.6gr 929ft/sec 27,500 CUP

DaveInPA · April 14, 2008, 04:51 AM

Thanks for the info Hank. I think the Gold Dot is a longer bullet, however, hence the strange load data. I'm going to use AA#7 or AA#5, since they have more traditional min/max load data listed for those powders.

Master Blaster · April 14, 2008, 06:51 AM

Speer's DNR for the load you are posting about is because below a certain velocity the jacket and core of the bullet may seperate leaving the jacket in the barrel. The next round fired may cause an overpressure situation and a kaboom. In other words in 9mm. you need maximum velocity for that powder for that load to be safe.

Other slower burning powders used for magnum loads (2400, H110, 296 etc) may have a DNR because the powder will not burn completely, in a reduced load, and can result in a stuck bullet as well.

DaveInPA · April 14, 2008, 07:15 AM

Thanks for that info Master Blaster. I'm thinking I'll just avoid Titegroup altogether with this particular bullet!

April 13, 2008, 09:29 PM	#1
DaveInPA Senior Member Join Date: January 20, 2008 Location: Berks County, PA Posts: 1,106	Speer manual - What is a DNR (do not reduce) load? Looking at the 9mm data in my speer manual for the 147gr speer gold dot JHP, the load data for Titegroup is confusing me. It has a minimum load of 3.3gr and says DNR (do not reduce). I'm assuming this means do not go below, 3.3gr which is all well and good. But this is where it gets confusing. There is NO max charge listed. What is going on here?

April 13, 2008, 09:35 PM	#2
CPTMurdoc30 Senior Member Join Date: February 27, 2008 Location: Stafford VA Posts: 969	I believe they are saying that is the only safe load to use. It is the min and the max. To reduced below that would cause a Kaboom and going over that load would also cause a kaboom. If you use a charge that is to light it may cause an extreamly high pressure spike too soon and cause your gun to become a part of your face. __________________ Solving Virginia's Ground Hog problems 50gr at a time.....

April 13, 2008, 09:38 PM	#3
DaveInPA Senior Member Join Date: January 20, 2008 Location: Berks County, PA Posts: 1,106	Well then, I won't be using Titegroup for that bullet. Thanks!

April 14, 2008, 04:51 AM	#5
DaveInPA Senior Member Join Date: January 20, 2008 Location: Berks County, PA Posts: 1,106	Thanks for the info Hank. I think the Gold Dot is a longer bullet, however, hence the strange load data. I'm going to use AA#7 or AA#5, since they have more traditional min/max load data listed for those powders.

April 14, 2008, 06:51 AM	#6
Master Blaster Senior Member Join Date: October 11, 1999 Location: One of the original 13 Colonies Posts: 2,281	Speer's DNR for the load you are posting about is because below a certain velocity the jacket and core of the bullet may seperate leaving the jacket in the barrel. The next round fired may cause an overpressure situation and a kaboom. In other words in 9mm. you need maximum velocity for that powder for that load to be safe. Other slower burning powders used for magnum loads (2400, H110, 296 etc) may have a DNR because the powder will not burn completely, in a reduced load, and can result in a stuck bullet as well.

April 14, 2008, 07:15 AM	#7
DaveInPA Senior Member Join Date: January 20, 2008 Location: Berks County, PA Posts: 1,106	Thanks for that info Master Blaster. I'm thinking I'll just avoid Titegroup altogether with this particular bullet!