Range Report Berger 175 OTM v. 155 Scenar Range Report

[Skigolfmike]

TVP had an open range day Saturday and I finally got to compare the 175 Berger OTMs to the 155 Scenars. Not sure it was the greatest day to test as it was very windy and gusty, or maybe it was With the rolling hills at TVP the winds can swirl a lot. First up was to check the 100 yard zero and get dope at 600 and 1000. I was estimating that the 175s were running ~2700 fps and the 155s were running ~2900 fps. The actual numbers in the AB app ended up being 2896 for the 155s (8.8 Mil) and 2721 for the 175 (9.7 MIl).

The true test was to get good dope at Intimidator position one. I have struggled here in the past and it's been really frustrating. I shot the 563, 950 & 938 targets, the 1165 was blocked by a tree top. Occasionally it would be visible, but seeing hits and making corrections was difficult.

I started with the 155 Scenars and I did manage to eventually get good dope. One thing I noticed with the Scenars was that I really struggled with windage. Also, the elevations for the 950 and 938 shots from the AB app were .4-.5 Mil high. (More on that later.) Follow up shots to verify dope were not very consistant either.

With the 175 Berger OTMs, using the dope calculated off the AB app, I got a 1st round hit at 563, and 2nd round hits at 950 and 938. Elevation was spot on and follow up shots were hits even with the highly variable winds. One I adjusted for wind I was pretty much spot on.

Afterwards I did some more testing on the bench to 1K and I concluded that even though the 155s have similar wind drift as the 175s (same wind correction at 1K), in the swirling winds the heavier bullet did better. I believe the reason is that a crosswind has to acclerate the bullet laterally until it's moving the same speed as the crosswind. The heaver bullet takes longer to accerate, but, in this case it takes longer to get to the target. That's why the wind corrections are the same. However, I believe in switching crosswinds, since the lighter bullet is accelerated laterally faster, in this case it won't shoot as consistant windage.

The other issue with the 155s seemed to be a problem with my load. I noticed it at 950 and then again at 1K from the bench. 1st 2 shots were good on elevation, then all shots started going .5-.7 Mil high. I'm running a pretty hot load to get the Scenars to run as fast as I am. I have not seen pressure issues, but The load has not been consistant as of late either. Might be time to rework the load a little.

I thinking the Berger 175 OTMs are the way I should go. The load shot really consistant and I think it's better in variable winds. Guess I'll have to order some more.

The load for the Berger 175 OTMs is:
43.5 gr Varget
Lapua 308 brass
CCI 200 primers
OAL 2.800", ogive 2.178" measured with Hornaday tool.
24" Krieger 11.25 barrel.

Load for 155 Scenar:
46.0 gr Varget
Lapua 308 brass
CCI 200 primers
OAL 2.825", ogive 2.200" touching to .001" off the lands.

 

[MitchAlsup]

Re: Berger 175 OTM v. 155 Scenar Range Report

I happen to run 47.8 gr Varget in Win cases (47.5 gr in Lapua cases) with the 155 scenars. My 24" tube sends them out in the 2925-2950 fps range. I'm getting 30+ reload cycles on my Win cases with this load. So while it is close to the pressure edge, it is not over it, in my rifle.

I pretty much agree with your notion that swirling winds can effect the lighter bullet more than the heavier one, even when the ballistics programs indicate similar windage performance in constant winds.

 

[Skigolfmike]

Re: Berger 175 OTM v. 155 Scenar Range Report

47.5 gr of Varget fills the case of my Lapua brass halfway up the neck. That's compressed a little isn't it.

 

[dieselten]

Re: Berger 175 OTM v. 155 Scenar Range Report

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: skigolfmike</div><div class="ubbcode-body">
...Load for 155 Scenar:
46.0 gr Varget
Lapua 308 brass
CCI 200 primers
OAL 2.825", ogive 2.200" <span style="color: #FF0000">touching to .001" off the lands.</span> </div></div>

This is where your inconsistencies are coming from. You can not have 1 bullet touching and another jumping. Jump them .020 and maybe fine tune the powder charge a little.

 

[Skigolfmike]

Re: Berger 175 OTM v. 155 Scenar Range Report

It's always the 3rd or 4th shot that starts going high, doesn't seem to have anything to do with whether the bullet is in the lands or not.

I was loading .010" +-.001" in the lands, but I got tired having a bullet stuck in the lands when I unloaded the rifle.

The original load was 45.4 gr of Varget. Calculating MV from collected dope said it shot 2900 fps. By the time I got to the end of the 8 lb jug of Varget, it was shooting 2820. I bumped the loaded back up to 46.0 and got some of the speed back. However, then I opened a new jug of Varget. Between pulling the bullet out of the lands and opening a new jug of Varget - I think I got this load all screwed up.

BTW, the MV for the 175s, Bergers or SMKs, did not change through the whole 8 lb jug, and the Bergers shoot great.

 

[turbo54]

Re: Berger 175 OTM v. 155 Scenar Range Report

Not to pull this thread from the dead, or anything, but I figured I'd chronicle (you know, for posterity's sake) my findings with these bullets over the weekend.

I have a class coming up, and rather than hammer 300+ rounds through my match rifle, I figured I'd finish up my "beater" Savage 308 and bring it. Trouble is since meloniting the new CBI barrel, it hasn't shot the 178hpbt Hornadys worth a shit. On saturday night, I realized I had ~325 scenars on the shelf, so I figured I'd give them a try.

I made a dummy cartridge loaded to 2.900", the limit of my AI magazines (front plate removed), and it didn't touch the lands. No idea how far off, but it ain't there.

I arbitrarily loaded my test groups at 2.850" tip to tip.

I tried 45.5, 46, 46.5 and 47gr of Varget, in (many times fired) Lapua brass with a Tula Russian primer. 47gr is probably right at max. Didn't have any stiff bolt lift, but got a whisper of an ejector mark on one of the 47gr cases.

No idea on velocity yet, but all loads shot less than 1/2moa @ 100 yards.

This is in a melonited 26" CBI 1-10 barrel on my Savage model 10.