Tight Chamber

[Blue Streak]

I have a new rifle chambered in 308 with a 95 Palma reamer. I plan to use the rifle for competion only and I'm trying to lock in on a bullet. I'm looking at the 155 scenar and the 175 SMK.

I measured to the lands with a 175 SMK and it was at 2.775 which is .030 less than most manual lengths.

If I start out with lower powder charges and check for pressure signs as I increase powder, is it okay to seat the 175 SMK deep in the case this far?

I read some things that suggest that this is an acceptable practice but I wanted to hear from you guys.

 

[ChrisGarrett]

Re: Tight Chamber

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Blue Streak</div><div class="ubbcode-body">I have a new rifle chambered in 308 with a 95 Palma reamer. I plan to use the rifle for competion only and I'm trying to lock in on a bullet. I'm looking at the 155 scenar and the 175 SMK.

I measured to the lands with a 175 SMK and it was at 2.775 which is .030 less than most manual lengths.

If I start out with lower powder charges and check for pressure signs as I increase powder, is it okay to seat the 175 SMK deep in the case this far?

I read some things that suggest that this is an acceptable practice but I wanted to hear from you guys. </div></div>

You're going to lose case capacity with the 175s seated that deep, so maybe try the 2156s or the Scenars and see.

Chris

 

[turbo54]

Re: Tight Chamber

Consider the Hornady 178 bthp. I load 45.5gr varget under a 175smk @ 2.790 - which jumps .010". It's compressed and goes ~2800fps from a 24" tube.

FYI - Normally you pick a bullet, then get a suitable reamer for it...not the other way around. I'm sure you'll be just fine though!

 

[Blue Streak]

Re: Tight Chamber

Yep, I'm learning as I go,..not always the best way but like you said, I'm confident that I'll be okay.

The 155 scenar looks really good if pushed,..seems to complete right along with the 175SMK. My barrel is 28" so I think I can get the velocity I need to make the 155 perform. I just wanted to try the 175s out to see how they woud work out.

 

[aloreman]

Re: Tight Chamber

go ten percent below and work up

 

[427Cobra]

Re: Tight Chamber

Get some 175s loaded at the lands with some Varget or RL15 lit off by Fed210 primers(notice I didn't include M) and go to town.

 

[Blue Streak]

Re: Tight Chamber

Thanks for the advise. I have some Varget, RL15, and I also plan to try out some N140. The Vit is a little more expensive but I wanted to give it a chance to see how it works out.

 

[MitchAlsup]

Re: Tight Chamber

The 155 scenar is just a hair longer than the 175 SMK with a similar ogive shape. So expect the same kinid of OAL when touching the lands.

 

[Blue Streak]

Re: Tight Chamber

The difference I see between the 155 & 175 is about 25 thou ogive to the lands.

I'll try both and chrony and see what happens. I hear the 155 do really well when pushed up to around 2800 - 2900 fps.

I'll just have to seat the 175s a little deeper,..start out with lower powder charge, and keep checking for over pressure indications.

Thanks for the advise

 

[Dave-O]

Re: Tight Chamber

My 308 is also chambered with the 95 palma reamer, 23in rock barrel... With the lot of 155 scenars that I have now, they are loaded at 2.790 and I am .005 off the lands, my go to load has been 46.1gr of varget which launches them at 2880..

Another powder to look at is 8208xbr, it also appears to be a little less temp sensitive..

 

[Blue Streak]

Re: Tight Chamber

Sub, that is exactly where I am with the 155s.

My barrel is a 28" 1:11 Krieger,..I don't think I'll have any problems driving the 155 fast enough as long as the 1:11 holds good.

 

[krw]

Re: Tight Chamber

It wouldn't be a big deal to have the rifle throat cut out an extra .035-.040". Gain your .025" in OAL, and still have a cushion of .015". I load my 175's at 2.815 OAL which is .010" off the lands and it will shoot like a house on fire. Good luck!

 

[Dave-O]

Re: Tight Chamber

Blue streak, My rock is a 11.27 tw. You'll be fine. Load em up and have fun.

My same load in my buddies 26" rock runs 2940.

 

[fredreded]

Re: Tight Chamber

I have a buddy that shoots 175 SMKs out of a 95 Palma chamber loaded to mag length with 45gr varget. Works well for him.

 

[Hookman]

Re: Tight Chamber

As everyone already stated, start low and work up.

Here is my best load with in GAP 22" Rock 5R barrel 95 Palma Chamber

Hornady 178 BTHP
LC/LR 05 brass trimmed to 2.005
44.0 Gr Varget
Wolf Primer
Ogive - 2.183
Velocity - Unk

5 shot group at 100 yards