Inconsistent 450 Bushmaster groups

[Rodahayes51]

I'm looking for some advice about 450 Bushmaster reloads. I'm going off data from Hornady that I found off the net. I'm loading HDY 250 gr. FTX, H110 powder. WSR primers, COL 2.233(measured from factory load). Table lists start 28.1, max39.2. I made 2 rounds at 28.1 and increased in 2 gr intervals to 39.0. MV ranged from 1500 to 2100 (factory 2100). Had 3/4" group at 36.1gr (MV 2000) but 1 1/2-2 inch groups above and below.

I made a second batch starting at 36.1 increasing by .2gr to 37.7. I had 1/2 inch groups @ 36.5 & 36.7 but MV only about 1900. With heavier charges the groups were all over the place. Some right, some left, some low. Checked the scope. It's tight. Is this the best I can expect for this recipe? I'd like to see the MV a little higher. Any suggestions? I'm shooting off a lead sled and can usually shoot 1moa.

 

[Curator]

You might try shooting off real sand bags; two under the fore end, one under the toe of the butt stock. The Lead-sled is not always the best for all rifles. To test loads it is usually a good idea to make 10 rounds of each "batch." With the 450 Bushmaster I would try 0.5 grain intervals first. Shoot 5, let the gun cool then the next five, and so on. Compare the results, record the best group then REPEAT the experiment. If one load is the best it will be the best the second time around. 2-shots or 3-shots do not make a reliable "group" statistically. It is possible to have two inaccurate shots hit in the same place, but not 5. 10 shots cannot be argued with. Pistol bullets are usually not made with the precision of dedicated rifle bullets. You may find different bullets that perform better than the Hornady FTX at the speeds you are driving these at. Their LEVEReverlution bullets are made for high velocity and rifle pressures.

 

[boommer]

rohdahayes YOU NEED TO STOP NOW! AND CALL Hodgdon not E- mail H110 is a 3% powder like 296 and others.The reason I say this is in magnum straight wall rounds you don,t reduce max charge more than 3% THIS IS A HEADS UP! CALL Hodgdon.I've called them many times on Diff things that I couldn't get data on from there site and things in gray area, THESE GUYS ARE SHOOTERS TOO.

 

[gamestalker]

I've shot off the lead sled, and off sand bags and much prefer the bags.

And as for your high velocity load not grouping as well, changing primers to a magnum may be what you need for proper / consistent ignition. H110 / 296 can be difficult powders to light up consistently. I have experienced the same senario with it, it's just the nature of the powder. H110 isn't be any stretch a difficult powder to manage, it just has it's designated charge table and must be used according to such.

Another possible cause could be using brass of varied trim lenghts, thus producing inconsistent crimps from one round to the next, another experience I've encountered.

And as already stated, H110 / 296 are in fact 3% powders, and altering the tables beyond those minimums could deffinitely be a problem concerning very inconsistent pressures and wondering pressure curves, both high and low, long and short sided. It's a very real risk of encountering squibs, and, or, near squibs, that could easily account for grouping problems. And when working with jacketed bullets it becomes exceedingly more of an issue. And keep in mind that the highest velocity load is not alwasy going to produce optimal accuracy, not uncommon at all.

And of course, trying a different bullet could be all that is needed to remedy the problem. They all fly and react to pressure gains differently.

GS

 

[ArchAngelCD]

I'm going off data from Hornady that I found off the net.

Is that data directly from Hornady or did you find it somewhere on the Internet and they credited Hornady? Be very careful using any load data you find on the Internet unless it's 100% verified from a reputable source like the powder manufacturer, bullet manufacturer and sources of that accreditation.

I just went and got my Hornady 9th Edition manual from the loading room and checked the data for the 450 Bushmaster and a 250gr FTX bullet. The COAL is 2.225" and the charge weights are 28.1gr to 39.2gr H110. Like said above, that is in direct opposition to what Hodgdon says is safe. If the Max charge is 39.2gr H110 the starting charge should be no less than 38.0gr. Even the normal 10% reduction from the Max would put you @35.3gr H110 so I really don't know what Hornady is doing. Also confusing is the data for W296 which is the same exact powder as H110 is 29.4gr to 40.4gr. This is not a good situation IMO.

If it were me I would be using Lil'Gun...

 

[Rodahayes51]

Inconsistent bushmaster

Thanks for your input. Guess I'll be ordering MORE bullets!