Brand new RPR(.308) OAL Issue/question

[SLuke]

Just picked up a brand new Ruger Precision Rifle in .308. Upon bringing it home I decided to take some measurements with the hornady tool and the bullets I intend to use(168gn Sierra HPBT MatchKings). I took 3 measurements and came up with the following numbers COAL- 2.865 and OGTB 2.221. Thinking that did not seem right because the coal with the bullet touching the rifling was .05 over max cartridge length, I then pulled out two other types of bullets i have laying around, first was a Sierra 165gn game king (spritzer boattail) (measured coal-2.84/ogtb-2.222) and then a Berger 185gn juggernaut otm tactical. (Measured Coal-2.909/ogtb 2.205).

With the measurements I took every one of those bullets would need to be loaded with alot of jump! There would be no physical way to have less than .03 of jump, and that would only be with the 165gn. This is my first .308 so I have no real point of reference and I’m hoping you guys can help me answer, is this normal? Isn’t this only going to get worse as the throat erodes? I suspect that it’s not normal and a trip back to the LGS tomorrow is going to be needed, but would like to hear the opinions of those more experienced than me.

thanks in advance for any words of wisdom you may have.

 

[rsmithsr50]

first comment would be the words
"ruger" and "precision" rifle
production rifles do not tend to have short throats.
if you really want a mag fed bolt gun, keep searching for bullets that work.
Hornady 130/135 has a long body.
what distance will you be shooting ?
call ruger and ask if it is normal

 

[rsmithsr50]

I am loading smk 175s at 2.28x in an ar10 and doing well so far.
yes that is a jump
just starting.

 

[rsmithsr50]

check mag length, I have seen some do 2.86

 

[Straightshooter1]

Just picked up a brand new Ruger Precision Rifle in .308. Upon bringing it home I decided to take some measurements with the hornady tool and the bullets I intend to use(168gn Sierra HPBT MatchKings). I took 3 measurements and came up with the following numbers COAL- 2.865 and OGTB 2.221. Thinking that did not seem right because the coal with the bullet touching the rifling was .05 over max cartridge length, I then pulled out two other types of bullets i have laying around, first was a Sierra 165gn game king (spritzer boattail) (measured coal-2.84/ogtb-2.222) and then a Berger 185gn juggernaut otm tactical. (Measured Coal-2.909/ogtb 2.205).

With the measurements I took every one of those bullets would need to be loaded with alot of jump! There would be no physical way to have less than .03 of jump, and that would only be with the 165gn. This is my first .308 so I have no real point of reference and I’m hoping you guys can help me answer, is this normal? Isn’t this only going to get worse as the throat erodes? I suspect that it’s not normal and a trip back to the LGS tomorrow is going to be needed, but would like to hear the opinions of those more experienced than me.

thanks in advance for any words of wisdom you may have.

When I got my Gen2 RPR .308 about 3 years ago, I used some 168 SMK's at .010 off the lands with a COAL at 2.858 and the lands was at 2.279". Using 42.0 grs of Varget in over 100°F days, I was getting groups less than .5 MOA. I didn't find it necessary to have a lot of jump with any of the bullets I used, which included 175 SMK's, 175 Berger's, 175 TMK'sl, 175 Nosler CC, 185 Bergers.

After 3650 rounds and having used Tubb's Final Finish System to smooth out the bore, the lands have moved .026 (of which .011 was from the Final Finish use). I still wasn't having a problem with .010 or .020 jumps with the SMK's. I didn't feel I needed to swap the barrel out, but I did because I wanted mount a Kreiger barrel and it was my birthday, so . . .

Now I have 2,400 rounds out of the Kieger now and it's done very well (as expected). The Krieger barrel has a chamber that's .030 shorter than the RPR factory barrel, which helps in loading out to the lands and having plenty of the bullets shank in the neck.

Oh, and BTW, I did have to buy a mag that allowed me to load them long. The factory mags were jut too short for my liking.

 

[SLuke]

first comment would be the words
"ruger" and "precision" rifle
production rifles do not tend to have short throats.
if you really want a mag fed bolt gun, keep searching for bullets that work.
Hornady 130/135 has a long body.
what distance will you be shooting ?
call ruger and ask if it is normal

my range is only 300 yds so almost all of my shooting with this rifle will be 2-300 yds.

 

[rsmithsr50]

then look at that Hornady bullet
130 is fine for 300, and will get you close to the lads from the mag. been there done that

my range is only 300 yds so almost all of my shooting with this rifle will be 2-300 yds.

 

[SLuke]

check mag length, I have seen some do 2.86

yes your correct. aics mags allow up to 2.86, but at that length the bullets I had on hand all had the boat tail in the neck so wouldnt i need to seat them a little deeper?

 

[XTR]

Factory barrels are notorious for long freebores.

load it at mag length and find a load that shoots. If that’s a factory barrel it’s only 20 inches long it’s not like you’re gonna be shooting it to 1000 very often. Work with bullets that are very jump forgiving. The Sierra match King’s In 175, 168, and 155 are all very jump tolerant.

 

[SLuke]

Factory barrels are notorious for long freebores.

load it at mag length and find a load that shoots. If that’s a factory barrel it’s only 20 inches long it’s not like you’re gonna be shooting it to 1000 very often. Work with bullets that are very jump forgiving. The Sierra match King’s In 175, 168, and 155 are all very jump tolerant.

thank you. I’m going to give Ruger a call tmw and see what they say. If they say it’s normal, I’ll do as you suggest.

 

[Straightshooter1]

yes your correct. aics mags allow up to 2.86, but at that length the bullets I had on hand all had the boat tail in the neck so wouldnt i need to seat them a little deeper?

. . . not necessarily. But there's no reason you shouldn't. You'll want to seat them to a seating depth that give you your best accuracy and that can be .060 (or even more) off the lands and they'll can do just fine. Here's a pic I just took of a 168 SMK seated out to 2.860 where you can see the relationship of the shank and boat tail with the case neck:

 

[SLuke]

. . . not necessarily. But there's no reason you shouldn't. You'll want to seat them to a seating depth that give you your best accuracy and that can be .060 (or even more) off the lands and they'll can do just fine. Here's a pic I just took of a 168 SMK seated out to 2.860 where you can see the relationship of the shank and boat tail with the case neck:

View attachment 1151771

Can I load like that? I've never had to load this long before and assumed that contact through the entire neck wouold be required?
Thank you for the helpful posts, much appreciated.

 

[Straightshooter1]

Can I load like that? I've never had to load this long before and assumed that contact through the entire neck wouold be required?
Thank you for the helpful posts, much appreciated.

Yes, you could load like that. And you don't have to load where their's contact with the entire neck, but there are limits to be sure that the bullet stays straight when being fed from the magazine (a much bigger issue for a semi-auto than a bolt receiver).

 

[rsmithsr50]

no,
about 3 thou tension should work fine.

yes your correct. aics mags allow up to 2.86, but at that length the bullets I had on hand all had the boat tail in the neck so wouldnt i need to seat them a little deeper?

 

[SLuke]

Update: I just spoke to Ruger, they provided me the following dimensions, bolt face to end of freebore 2.138 +/- .015, and 2.3025 +/- .015 bolt face to the start of the rifling. Which both appear to be SAAMI spec. If I am reading the SAAMi Drawing right, and assuming my barrel is made to spec, my OGTB measurements(2.2'ish) are putting the bullets in the lead, not the rifling, and in order to hit the rifling I would need to load even longer. This would align with what you guys have been saying about production rifles having long throats. I know I am probably completely overthinking this, and I should just go shoot the thing and not worry about it, but like I said earlier, Ive never had a rifle require such a long COAL to touch the rifling, so if it's not right I want it fixed beofre I send a round down the barrel.

Thank you all for the information, it has been very helpful.

 

[Doug Beach]

It will probably shoot 168 SMKs pretty well with a long jump, assuming it is otherwise a precise rifle.
You can also just load long & single feed. Unless you are shooting PRS, or using the rifle for law enforcement, there isn’t much need for mag feed, in a precision rifle.
As far as how much bullet needs to be in the case, unless you are going to be handling the loaded rounds roughly, the answer is, not much. If you have at least .100” of full diameter bullet in the case, I wouldn’t worry about it.

 

[Oleg S]

Update: I just spoke to Ruger, they provided me the following dimensions, bolt face to end of freebore 2.138 +/- .015, and 2.3025 +/- .015 bolt face to the start of the rifling. Which both appear to be SAAMI spec. If I am reading the SAAMi Drawing right, and assuming my barrel is made to spec, my OGTB measurements(2.2'ish) are putting the bullets in the lead, not the rifling, and in order to hit the rifling I would need to load even longer. This would align with what you guys have been saying about production rifles having long throats. I know I am probably completely overthinking this, and I should just go shoot the thing and not worry about it, but like I said earlier, Ive never had a rifle require such a long COAL to touch the rifling, so if it's not right I want it fixed beofre I send a round down the barrel.

Thank you all for the information, it has been very helpful.

Have you tried any factory ammunition?

View attachment 1151796

 

[Oleg S]

View attachment 1151810

This is factory barrel with long throat and factory ammunition.
Have you tried any factory ammunition yet?

 

[Oleg S]

And this is as Doug Beach said seat long and single feed. Same factory barrel

 

[SLuke]

This is factory barrel with long throat and factory ammunition.
Have you tried any factory ammunition yet?

I havent. I just picked it up last night, and since it had no optic (coming today) and it was dark, I decided to fondle it by taking some measurements and sizing some cases that were range pickups in the recycle bin to different shoulder set backs just to see which felt best on bolt close, (saami +.004). I have 20 rounds of nothing fancy federal .308 ammo to shoot to break the barrel in and then 100 rounds of federal gold match to finish break in. I just didnt want to shoot it if the barrel was out of spec and needed to go back. I would rather send it back now and get it right, than try shooting it and deal with it later.

By the responses it appears that this is probably the norm for factory rifles, that the measurements I took are no predicition of actual on paper performance, and I am most likely just overthinking the whole thing.