GLSHOOTER: Feb 21, 2012 at 9:20pm
I made my second real serious trip to the range on Sunday and managed to get the numbers crunched. This may be a little disjointed as I need to work up the data from previous trips to post but thought I'd like to get the ball rolling on this.
Before I start here are some disclaimers.
First off I don't claim to be a Benchrest shooter with an AR. Anyone that has shot an AR off a rest knows they are not the easiest animal to shoot well. Those round hand guards don't bode well for consistency off a rest. I can shoot pretty well at times and I try to realize the platform makes a huge difference. Shooting 20 sub-MOA groups with one of my 204's is pretty easy. For me to get that many with an AR takes me forever and I ain't getting any younger!!
Second thing is that I post all the pertinent load data for my records when I shoot targets. Thanks to the quality and intent of my usage of BHW barrels I have started chasing the lands and loading longer than mag length for matches. These are shot single shot so the ability to load long is an option that is to be enjoyed. Oddly enough I had shot some of the same loads at mag length previously and found the velocities slightly lower and the accuracy not statistically different with this bullet. Remember this is MY data, not YOURS. Duplicate it all you want but when you get behind that trigger it is all on you no matter what the outcome.
The charge weights on the powder are not necessarily found in every book we have as we all know different makers have different MAX loads. Also with different chamber and throat dimensions some rifles don't mind it hot. The polygonal rifling comes into play with BHW barrels. Everything I have shot has shown a consistent increase in velocity over book values. The cases are not showing pressures like I see in my standard alternative rifles in this chambering.
The third area I might point out is that the TEMPERATURE of the testing. These are mild temps for this load work ups. When I lay down and shoot a match this summer at 110 it may be totally different. That is one reason I chose H4895 for these tests as it is one of Hodgdons’s Extreme powders and HP guys all over the US value it for its' temperature tolerance.
I selected the 87 grain Hornady HPBT bullet for several reasons. First of all it is a common one to obtain. I have used it in three 6X45's I have shot in matches since the 80's and have taken a bit of metal home for my efforts. The BC is not real low at 0.376 and I can get the velocity up enough to make do with the short 600 yard maximum I intend to shoot with this rifle. Also the price is quite reasonable though I will be trying out some of the higher end Berger match bullets in the next month.
Cases were formed with Winchester once fired commercial brass. All were expanded with a Sinclair mandrel after being run through a Dillon sizer/trimmer. Expansion of the .223 neck to .243 resulted in a shortening of the neck by approximately 0.008 and this was taken into account on the trimming process. All were chamfered inside and out. Primer pockets were uniformed and flash holes were deburred. One thing of not was that these cases fired today were expanded with a mandrel of 0.241. Previously I had sized some necks with a 0.259 bushing. Nominal neck size on these unturned cases is 02.61 to 0.262. The bushed neck cases showed an increase across the board of approximately 50 FPS.
All charges were dispensed and weighed with a PACT electronic system.
This trip was a reshoot of some previously shot loads that showed promise with a bit extra powder charge to see how the rifle would respond to the challenge. Across the board I found the velocities today wee about 50 FPS less than previously tested. As mentioned above I suspect it was due to a lower neck tension on the bullet in this test set. Conditions were clear and sunny. Light winds from one to five MPH at 3 o'clock.
The best load with H4895 today was 27 grains. This is getting pretty full considering how long these bullets are. Velocity was 2934 with no signs of pressure with the primers not being flattened, no primer flow, and no bright ejector marks on the case head. One round got away on the two groups fired at this level.
This is a very usable load. Oddly enough the velocity of this one was almost identical to a previously shot load that showed excellent grouping with a lower powder charge. I believe that off a bipod and a rear bag that I can pull some good stuff out in the next zip code. I suspect that the harmonics of this load velocity agree with the barrel and I may see similar performance as I dance around that number.
On a whim I grabbed a bottle of H335 the day I was loading up these test loads. No attempt was made at a load work up and I selected a charge that from what I could see on published loading data with bullets seated shorter this one would be safe. Nothing like striking out on your own and not wanting to strike out!! Seating depth was the same as the other 87 grain loadings as changing more than one parameter of a test series midstream would invalidate the data gathered.
You may note the velocity is somewhat lower but I expected this before hitting the range. The good thing is that once again the pressure signs were not there and there was a relatively good amount of case capacity left for future testing. I have shot this powder before in the 6X45 and found it forgiving but I have never challenged it at more than 100 degrees ambient. Phoenix will be the test by fire in this sumer on this propellant. I did get a bit rambunctious on one trigger pull but I'll let the holes do the talking on this one.
It would seem that H335 is another avenue for experiment. I'll be wringing this one out. I have looked into the long range HP loading preferences and RL15 has tuned up as another heavy bullet choice. I will more than likely run these two parallel and see what happens. Of course introducing the big Bergers will also be a step in the evaluation progression.
Luckily for me there are two groups shooting F-Class here in Phoenix and I have got hooked in with both of them. I'll do a recon on the next local match and then jump in with both feet. I'll post some of my previous results later on in this thread with some observations and my opinions on what makes this one tick.