155gr 308 chamber length and oal

M

matm

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I have an unfired custom rifle that I'm going to work up some loads for and it Is throated for 155gr bullets. Using an oal gauge, I found that the bullets seem seated pretty far in the case before touching the lands. The 155gr SMKs (2155) have a max oal of 2.760

The 155gr sencars are even shorter at 2.710

The 155gr berger vld are good to go at 2.850

The sencars are in the case almost a half inch it seems


Should I just start low and work up the loads, or should I have the chamber opened up a bit? Any help is appreciated, I was going to use the 2155 first with a 10 thou jump which makes the oal at 2.750

Thanks!

-mat
 
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Your smith should be able to run a throating reamer in if you want more space. Unless you really want to chase the FPS, I wouldn't bother. Lots of distance to chase the lands as the barrel wears.
 
That's good to hear, its just all of the data I can find has the oal in the 2.810 area. I understand factory rifles are usually a little loose, this is a Krieger barrel custom chambered so I expect it to be tight. I just want to keep the pressures safe.
 
Load the bullets .020" off the lands with 46.0 gr of Varget. You might want to start at 44.0 or 45 but will likely find the sweet spot at 46.0 like 80% of the target rifle shooters using 155 gr bullets.
 
I was thinking at starting around 44 with lapua brass and work up to 46. I mostly wanted to know if the oal is reasonable and not crazy short.
 
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That's a bit on the short side if you're touching the lands at that COAL.
155.5Gr bergers should fit great in it though, they're probably what the reamer was made for.
 
You should be able to load the Lapua 155 Scenars to 2.800" which is "spec" and 2.710" OAL means less powder capacity. The Lapua is very long and gunsmiths chamber to match.
 
The Berger's I have definitely fit the chamber better, the sencars seem to have a pretty stout ogive. I bought a bag of 500 SMK with the understanding they were the 2156 with the longer profile, turns out they weren't. I have a couple hundred factory moly coated sencars that I don't think I'll load due to case capacity. I guess I have 700 bullets to sell! I'll switch over to the Berger's. I'll load a few of the smks for the fun of it, if they shoot alright it would be a cheap plinker for playing around.
 
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It seems your chamber is cut for one specific load/bullet combination. If you want to stick with that, fine. For more versatility, I would re-cut the throat for a more flexible reloading situation. You don't mention the twist rate. If it's 1:10, you can try bullets up to 220gr if you re-throat your chamber.
 
It's a 1:10 5r barrel so it would work for most weights. I'm going to play with the 155s for now and if I'm going to keep the rifle, I'll consider a re chamber.
 
Play with the Berger’s for sure. I load them to 2.883” coal with 45.6 Varget in Lapua brass. Getting 2930 fps in a 26” 1:10 rot.
 
That is a short throat for sure. If it was my rifle I would load 20 thou off the rifling and carry to develop a load. You may need less powder than some others to get the velocity you want. The throat will advance about 10 thou a year, with erosion.

If I make a rifle for 155s, I use a 1:14 twist. 1:10 is for the 200 VLDs.
 
Then u can get Henry to chamber it for what u want, just send him a bullet in a case where u want the bullet to sit and he cuts the chamber to fit. Jeff. away for the rest of the day. I like the 155.5 triple nickel beegers
 
1:10 is fine with 155's and improves BC. 155.5's want 1:12 or faster.
Berger has a good calculator for that stuff.
 
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