IMR 4350 & H 4350, the same?

[Pheroze]

Hi,

I have been developing a load for the '06 using IMR 4350. I can only get H4350 to replace the 1lb container I have (stocking up now). The fellow advised they could be swapped grain for grain. I am not so confident. Anyone know the relationship?

 

[PHOENIX PHIL]

Very close but not the same. Just because of lot to lot variation, I would not immediately swap grain for grain. You should definitely back off from your established load for safety. From there presume you're redeveloping your load for the particular caliber and bullet. Hopefully the load will be close and maybe even the exact same weight as the IMR version.

 

[tarbe]

I have never found them to be the same.

Tim

 

[JimP]

I would start going to a different store if the person at the counter told me that you could swap them grain for grain. That is a big problem waiting to happen.

As for a relationship between the two, Hodgdon owns IMR and manufactures IMR 4350 but that doesn't make it the same as H4350. They have similar burn rates but are not interchangeable.

This is where you need to look at the loading in a reloading manual, if the manual that you are using doesn't list both powders for your bullet choice check the IMR and Hodgdon sites on line to see what they recommend.

You will also find that Hodgdon 4350 is an 'Extreme' powder and will give consistent performance over wide ranges in temperature.
IMR 4350 isn't, and you'll get different performance n hot and cold conditions.

 

[Tim Beahan]

Good advice, so far- similar, but not the same.

 

[Pheroze]

Thanks guys. I wasn't comfortable with the advice. I have several manuals but they are not consistent. For the Hornady BTSP 180 gr interlock the published maximum is 54.5gr imr 4350. In the Lee manual the published max for 180gr is 56.5. I stuck to the hornady data and stopped at 54.5gr and have it going about 2620 fps (22" barrel). This gave my best groups of those tested. But the hornady manual does not have H4350 for the 180gr and Lee publishes 57.5 never exceed. I am going to email Hornady to see what they say the max load for H4350 is.

 

[JimP]

Odds are Hornady will refer you to purchase their newest manual instead of giving you any load data for that bullet.

Hodgdon list 57.5 grains of H4350 as the max for a 180 grain bullet with 52 grains being the starting load.

http://www.hodgdonreloading.com/data/rifle

 

[Pheroze]

Strange that the hornady manual has a max that is two grains less for IMR than Lee.

 

[JimP]

Strange that the hornady manual has a max that is two grains less for IMR than Lee.

You will find when you open up any 2, 3, 4, or how many other manuals that the max loads will very seldom be the same. It all depends on what they are using to measure the pressures of the loaded round and how they are doing it, barrel length, temperatures and other variables.

That is why they tell you to work up to a max load for your firearm and to never start with the max load listed.

 

[Steve Steyr]

Echoing the "similar but not the same" chant. Supposedly H4350 is rated slightly slower than its IMR brother. But my last pound of H4350 was ever so slightly faster than my 15 year-old pound of IMR4350 and my newly purchased pound of IMR4350. I suspect the lot-to-lot difference of the H product is no more than the lot-to-lot difference of the IMR product but there's no reason to tempt fate at any stage of the reloading process.
And then there is AA4350, which gets little mention.

 

[blackdog001blackdog001]

They are not the same and you really should get a current loading manual and develop your loads off the starting recommendations therein.