Anyone try IMR 4955 yet???? Well I have now!!!!!

Jabey9210

Jabey9210

Member
I'm working up loads for a .270 with 140 grain Bergers and didn't have any powders suited for the job. I have a few on hand that I tried but wasn't satisfied. I went looking for some H4831 and drew a blank. I saw this powder which falls right next to H4831 in burn rate and it's supposed to be the cats meow for the 270. Of course that's coming from IMR's mouth. I can't find much on this powder in regards to anyone that's actually used it. Anyone given IMR4955 a whirl yet???
 
Looks like I'm the only Guinea pig so far. I can tell you hodgdon needs to back the max load for this recipe a bit. I'm shooting a Ruger M77 mark II in 270 with 140 bergers and CCI 200 primers. As per hodgdon min=54.0 max=59.0. I was seeing extreme pressure signs at 56.9 grains as in flattened primers and ejector marks. I decided to keep going to see how each .3 grain powder increase acted and my first shot at 57.5 grains, which is 1.5 grains below published max I blew a primer so needless to say I didn't fire any more.


Up to that point the powder showed good velocity and really low ES. I'm just glad I started low and worked my way up instead of starting in the middle somrwhere.

I wonder how they come up with their max loads??? I can shoot a max load of IMR 7828ssc and H414 with minimal pressure signs out of this gun but with this powder I'm a full 2 grains under published max and see worse pressure signs!!!
 
Every rifle is different.

Also...........

Check 3 loading manuals and you will come up with three different manuals.

Answer, own 4 or more manuals, check them all, work up wisely.

Good luck, and always were safety glasses!
 
Originally Posted By: Jabey9210

I wonder how they come up with their max loads??? I can shoot a max load of IMR 7828ssc and H414 with minimal pressure signs out of this gun but with this powder I'm a full 2 grains under published max and see worse pressure signs!!!

Every rifle will react differently. Also, how were the bullets seated? Neck tension, FL size, etc...it can all make a difference in the way pressures are made in the rifle.
 
Originally Posted By: pahntr760Originally Posted By: Jabey9210

I wonder how they come up with their max loads??? I can shoot a max load of IMR 7828ssc and H414 with minimal pressure signs out of this gun but with this powder I'm a full 2 grains under published max and see worse pressure signs!!!

Every rifle will react differently. Also, how were the bullets seated? Neck tension, FL size, etc...it can all make a difference in the way pressures are made in the rifle.


Bullets all seated .030 off the lands. All brass was once fired from a different gun and FL resized and all trimmed to length. I realize all guns are different I just thought it to be strange that with one powder I could go over max while with another I couldn't even come close when the data comes from the same source. I could definitely understand if I was using data from two different sources. It does show on hodgdon's site that the 4955 powder at max is 62,900 PSI where 7828 is 50,600 CUP. Not sure the difference in PSI and CUP but I'll look it up.
 
Accuracy was pretty good. The gun is not a super sub moa gun but they were grouping on par with the other powders that I tried but had more velocity. I am going to use it. It seems like a good powder the extreme spreads were all decent with 10 being the best and I think something like 43 being the worst in the higher end loads. Most were in the mid 20's fps for five shots groups in all loads I tested which was a total 10 loads. I had 15 different charges loaded but pulled the last ones because of pressure. I did so many because I couldn't find any data outside of hodgdon's website and plus I had the time. I'm sure I can get the groups to tighten up even more by playing with seating depths but overall I'm pretty satisfied with IMR 4955.
 
Originally Posted By: ackleymanEvery rifle is different.

Also...........

Check 3 loading manuals and you will come up with three different manuals.

Answer, own 4 or more manuals, check them all, work up wisely.

Good luck, and always were safety glasses!

I usually do but that's the problem I only had one resource because of the powder being new. I'm not new to reloading and I'm not surprised I saw pressure being well under the published max load because I understand it is just that a published max load it's not my max load. I'm just curious as to why from the same resource can I shoot over max with one powder and nowhere near max with the next with the same firearm and when the data is coming from the same source.
 
I agree. There isn't a lot of loading data on the new IMR powders. You go to the IMR web site and just get minimal load data. I bought some IMR4166 and can't find anything on 5.56 service rifle loads, or 7.62 either. The IMR 4166 just says 22.0 min 24.0 max for .223, using 68 grain HPBT's, but I am loading 69 grain Sierra HPBT's, not a lot of wiggle room there.
 
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