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Posted: 11/19/2002 6:18:11 AM EDT
[Last Edit: 11/19/2002 9:17:57 AM EDT by Bartholomew_Roberts]
Well, I finally got a chance to test some of Black Hills 75gr Heavy Match load that is loaded with Hornady's 75gr. BTHP. Unfortunately, I didn't have any experienced match shooters to help me this time, so the results are probably only marginally useful.

Conditions: 65F, about 800' elevation, 36% humidity, wind 10-15mph with gusts to 30.

Shooting was done from sitting at a bench, no sandbags or other support, open sights (stock), 16" 1/9 chrome lined Bushmaster barrel. Targets were 8.5x11 sheets of paper (several sheets for 75gr @200 and 300).

First conclusion: Under these conditions, the 1/9 16" barrel will stabilize the 75gr out to 300yds. Accuracy with this rifle/shooter/ammo was less than impressive; but when the rounds did hit the paper, there was no keyholing or anything else that would indicate the kind of instability you see with 62gr in a 1/12 twist.

Second conclusion: For this shooter/rifle, the 75gr is probably unacceptable as accuracy was inadequate at 300yds and pretty marginal at 200yds. To give you an idea of how much was the shooter and how much was the ammo, I compared the following groups:

200yds with reloaded LC brass, 55gr
best group: 6"
worst group 12"

200yds with Black Hills 75gr BTHP
best group: 19"
worst group: unable to measure but wider than 20"x29" carboard backing

No group comparisons at 300yds as we ran out of ammo, targets and patience trying to get a group with the 75gr. Few rounds that did find target left nice round holes you would expect from a properly stabilized round.

Part of this may have been rifle preference as it didn't care much for the 68gr Hornady BTHP at shorter ranges either. At longer ranges though, the 68gr grouped in the same range as my best/worst 55gr. groups.
Link Posted: 11/19/2002 11:59:04 AM EDT
Im sorry but 3MOA at 200 yards is stable. Over 8 MOA at 200 yds is NOT stable. Even if its not so bad as to key hole its certainly not something any of us would like to see as a result. I doubt anyone here thinks an AR shooting match ammo putting up groups worse than an AK is "stable" The rounds not hitting the target probably were the ones that would have keyholed but flew way off target.
Link Posted: 11/19/2002 12:12:35 PM EDT
I'm gonna have to agree with DevL here.

I wonder how much the extra velocity gained from a 20" 1/9 would have helped.

Anybody have a chance to try it?
Link Posted: 11/19/2002 12:56:26 PM EDT

Over 8 MOA at 200 yds is NOT stable. Even if its not so bad as to key hole its certainly not something any of us would like to see as a result.


I definitely agree, although I'd be willing to bet that a better shooter would have cut that down some. I know the 55gr load will do MOA in the right hands from the same rifle at 100yds - so I figure I add about 3-4 MOA on my own. Also, I don't normally shoot groups so some of the tricks (like a consistent hold on the same portion of the target) are new to me.


The rounds not hitting the target probably were the ones that would have keyholed but flew way off target.


I had a yellow clay berm behind the target that would send up a nice puff of dust with every round. Out of 50 rounds, only two didn't impact in the vicinity of the target (of course, this was observed from 200-300yds away, so my perception could be faulty regarding how close it was to the target).

One impacted about a foot over the target against the berm.

There was another impact that was bizarrely off target and way up the berm, about 30ft. up and right. I assumed it must have been a ricochet since the majority of the rounds were in the target area, although I wondered whether what you described wasn't the problem.

It may be that the 75gr was right on the edge where some rounds were hot enough to be semi-stable and some weren't.
Link Posted: 11/22/2002 2:24:44 PM EDT
I wonder how much the extra velocity gained from a 20" 1/9 would have helped. Anybody have a chance to try it?
View Quote
I picked up a box of the 75 gr BH to try. Ran out of daylight so only got one or two groups through a 20" 1/9 but I was getting 3"+ at 100 yds where the BH 52 gr & 68 gr normally run around 1.2" at 100 yards in that rifle. No keyholing though.
Link Posted: 11/22/2002 5:11:03 PM EDT
75Gn Hornady match shoots great out of my 24" 1:9 brl. No trouble consistantly hitting the 8" gongs at 300meters.
Link Posted: 11/22/2002 7:05:47 PM EDT
Rifles with a 1\9 twist rate will sometimes have problems with bullets 75gr and heavier. Once you reach 80gr, you need a 1\8 to keep the groups tight enough to hold the 10 ring. 1\9 and 75gr or heavier usually result in larger than normal groups, espically at longer ranges. Some rifles can shoot well with the heavier rounds, but not many.
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