OAL of factory 308

TinkerBell

TinkerBell

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because jerry found the chamber is tight to sammi spec and has an issue with longer rounds (2.80 vs 2.73/2.74) i am curious on what the over all length is on the factory ammo you are using, interested in norinco, hirtenberger especially..... also curious about the "ballistic tip" variations from the different manufacturers. if you have it in 308, post it and let us see.

Federal sierra 165 game king and got 2.70"
hornady 178 grain hunter precision ammo measures in at 2.80
Federal Gold Medal Match 175gr Sierra Match King 2.800" (consistent COAL)
Hornady Superformance Match 168 gr A-max 2.805" - 2.810"
Hornady Superformance 165 gr SST 2.745"
Hornady American White Tail 150 gr Inter Lock 2.745" - 2.750"
Hornady TAP 168 gr A-Max TAP FPD 2.800" - 2.810" (unimpressed with COAL on those)
 
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It's going to depend on the bullet design. When you're reloading you're going to have to use a tool to check your bullets relationship to the barrel. Hornady has a nice one., or make up some dummy rounds like Jerry did. The nice thing is, there's a lot of .308 that is just sub 28
 
SAAMI maximum OAL is primarily relevant for function through magazines. Otherwise, OAL comparisons are only relevant when you are comparing different loads with the exact same bullets. Comparing OAL between different factory ammo will tell you nothing about how it fits your rifle.
 
tjhaile said:
SAAMI maximum OAL is primarily relevant for function through magazines. Otherwise, OAL comparisons are only relevant when you are comparing different loads with the exact same bullets. Comparing OAL between different factory ammo will tell you nothing about how it fits your rifle.
Click to expand...

then why is jerry saying oal of 2.80 are jamming the bullet into the rifling ?? i did not ask this in regards to magazine issues......
 
Federal Gold Medal Match 175gr Sierra Match King 2.800" (consistent COAL)
Hornady Superformance Match 168 gr A-max 2.805" - 2.810"
Hornady Superformance 165 gr SST 2.745"
Hornady American White Tail 150 gr Inter Lock 2.745" - 2.750"
Hornady TAP 168 gr A-Max TAP FPD 2.800" - 2.810" (unimpressed with COAL on those)
 
I've been doing the old jiffy trick for years in my load development adventures. If any of you guys are really serious about precision and function, heed Jerry's words.
If not... keep on jammin those lands!
 
tjhaile said:
SAAMI maximum OAL is primarily relevant for function through magazines. Otherwise, OAL comparisons are only relevant when you are comparing different loads with the exact same bullets. Comparing OAL between different factory ammo will tell you nothing about how it fits your rifle.
Click to expand...

Totally agree, depends entirely on the rifle. One of my best loads was 2.850" and it wasn't jamming the lands.
 
When setting up a bullet for a mag fed rifle, there are a few measurement that have to be considered...

1 - what is the max OAL that will fit into the mag?

2 - what is the ideal OAL that will feed in the rifle? They can be different and in the case of the BCL, I am finding that shorter for the Hrn 150gr FMJBT is a good thing.

3 - What is the max OAL so that the OGIVE of the bullet doesn't jam? With a semi auto, I would never want a bullet to be that close to the lands that a chance of jamming can occur. In the vast majority of factory chambers, the throats will be on the long side if all possible - lawyers don't like blown up rifles - and long throats help to reduce peak pressure of the ammo. With a long throat, it is very hard to jam into the lands with any ammo that will fit in the mag.

With the first BCL that I tested, that doesn't look to be the case. Chamber has a very nice short throat requiring an OAL with the HRN 150gr FMJBT to be shorter then max mag length and keep the ogive off the lands. It actually put the cannelure of the bullet right on the desired case length... how nice.

Bullets all have differing nose shapes so you can't go by bullet weight. You need to measure where is the ogive in relation to the OAL in relation to the chamber throat.

In general, not a problem.. Glad I checked this BCL. Might have been more spicy then I wanted otherwise.

Jerry
 
Affter reading some of the post regarding bullets hitting the lands I became worried. I had just finished determining my hunting load and that gave me a col of 2.810. So last night I made up a few dummies to see if there would be contact I went out to 2.815 with out any marking on the bullet a 168gn tsx. That being said I know when to take advice from people who know more so I made up a new Batch or rounds dropping the charge weight .2 gn and seating the bullet down to 2.800. I hope this gives me simular results as I was getting with the longer round.
 
Measuring OAL is really only good for finding out what fits, feeds in and (probably most important of all) what feeds from the magazine. Other than that, OAL of the round really doesn't matter and can change from finished round to finished round - using bullets from the same box.

Measuring to the ogive is best accomplished with a bullet comparator.
Stoney point (bought out by Hornady some time ago) is a good bet, and they have an angled one that works great on the AR.
 
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