Rich 10mm
Member
Should I bother crimping 5.56 for an AR-15? I’ve seen mixed opinions.
5.56 crimping
- Thread starter Rich 10mm
- Start date
- Status
Demi-human
maybe likes firearms a little bit…
Nah.
243winxb
Member
Neck tension should be high enough to keep bullets from moving.
Chambering a round may cause the OAL to get longer. Or shorter if bullet contacts something on chambering. Run a few rounds in and eject without firing. Measure OAL.
Measure the case neck before and after seating a bullet. After seating the outside diameter should be larger by a minimum of .002" This will give the minimum bullet pull of 35 pounds. More is better in an auto loader.
Check expander diameter. Should be about .2225" or a hair less.
No bullet cannelure, no crimp.
Crimping will help a little , but is not needed with good neck tension.
There is roll , taper and stab crimp types available. Brass is best trimmed to all the same length.
I dont crinp.
Chambering a round may cause the OAL to get longer. Or shorter if bullet contacts something on chambering. Run a few rounds in and eject without firing. Measure OAL.
Measure the case neck before and after seating a bullet. After seating the outside diameter should be larger by a minimum of .002" This will give the minimum bullet pull of 35 pounds. More is better in an auto loader.
Check expander diameter. Should be about .2225" or a hair less.
No bullet cannelure, no crimp.
Crimping will help a little , but is not needed with good neck tension.
There is roll , taper and stab crimp types available. Brass is best trimmed to all the same length.
I dont crinp.
Last edited:
Rich 10mm
Member
In your opinions do you think crimping could effect velocity?
Rich 10mm
Member
When I reload I consistently get lower velocities than those in my hornady reloading manual.
Rich 10mm
Member
PS I tested the powder load on 2 scales.
243winxb
Member
Many things have an effect on velocity. When there is a lot of difference between fastest and slowest, its something to look at when using the same loading.
Rich 10mm
Member
I’m talking 64 extreme spread over 5 shots
Rich 10mm
Member
I’m admittedly somewhat new to bottleneck cartridge reloading. My handgun loads are very consistent and I’m happy with them. Am I missing something that doesn’t crossover to the rifle cartridge world.
Rich 10mm
Member
I’m using 23.3gr AR-Comp with a 55gr Hornady FMJ. Listed velocity for this load is 3100 FPS. I’m averaging 2767 FPS. Granted the test barrel is 20” and I’m using a 16” but I still think that’s a severe drop for an extra 4 inches of barrel length
243winxb
Member
Barrel length makes a difference. The Alliant data uses a 24" barrel to get their velocities, so nothing to compare there.
M16A1 with 14.5 " barrel averaged 2766fps.with a 55 gr Hornady fmj . Spread 113 fps 12 rounds. imr 4198 powder.
Wait and see what other forum members are getting with that powder.
Could be better? My guess. Have not used a chronograph since the 70s.
M16A1 with 14.5 " barrel averaged 2766fps.with a 55 gr Hornady fmj . Spread 113 fps 12 rounds. imr 4198 powder.
Wait and see what other forum members are getting with that powder.
Last edited:
243winxb
Member
Is Hornady using the same data with more then 1 bullet? They seem to use generic data .
Different Bullets make different pressure & velocity.
Alliant data
maximum loads. Work up as always.
Different Bullets make different pressure & velocity.
Alliant data
maximum loads. Work up as always.
Last edited:
Demi-human
maybe likes firearms a little bit…
This, as well as a number of other things can result in lower velocities.
Whether the data was tested with a 223 and merely carried over to the 556 data, the chamber dimensions of your rifle, the throat it has, case capacity of your brass, as you stated the barrel length and even more.
If a bullet has a cannelure, and the proper roll crimp was applied tightly, and the measuring devices were sufficiently sensitive, you may be able to tell if the crimp can cause the powder to burn more efficiently or cause some other velocity or pressure change.
Many subtle changes can impact the pressure and burn of a fired cartridge. Loading "into the lands" will give higher pressure and velocity for the same amount of powder. Sometimes dramatically so. As an example.
If I recall, 2800 was about all I could coax from my AR, a Hornady soft point 55 and TAC.
The important thing is if the holes are showing up in the right spot...
And don't drive yourself nuts with chronograph numbers yet. It's an AR, if it accurate and works, what more can you ask for?
Wait. Is it an AR? I guess I just inferred from the barrel length what it was. My bad...
Varminterror
Member
- Joined
- Jul 17, 2016
- Messages
- 14,947
Don’t crimp 5.56.
Crimp is a band-aid for a bad charge weight if you have any improvement in consistency. Develop your charge.
Neck tension and crimp are not equivalent.
64fps ES isn’t terribly uncommon for loads which weren’t developed specifically to yield low ES. Non-match bullets, maybe an imperfect powder selection, mixed brass, or mixed firing brass without annealing, inconsistent brass... 64 ES might even be accidentally LOW ES if the load development was simply start low, work high, and look at group size.
Crimp is a band-aid for a bad charge weight if you have any improvement in consistency. Develop your charge.
Neck tension and crimp are not equivalent.
64fps ES isn’t terribly uncommon for loads which weren’t developed specifically to yield low ES. Non-match bullets, maybe an imperfect powder selection, mixed brass, or mixed firing brass without annealing, inconsistent brass... 64 ES might even be accidentally LOW ES if the load development was simply start low, work high, and look at group size.
Rich 10mm
Member
55 gr Hornady FMJ BT om top of 23.3 gr or AR-Comp COL 2.25
entropy
Member
As hdwhit said, when I load 55 Hornady FMJ, I give them a slight crimp. anything without a cannelure, neck tension is enough.
Not knowing the particular case capacity, but using a default 28.8gr H2O . . .
Quickload gives me 3,017fps out of a 20" barrel, dropping to 2,848 in 16"
Your velocity of 2,767fps isn't all that surprising. (An effective barrellength of 15" would account for it completely)
Also... just a 4% drop in Powder Lot burn rate would also account for it, as would any slight variation in barrel internal dimensions.
Never chase the manufacturer's data ... it'll break your heart like a high-school Prom Queen.
Quickload gives me 3,017fps out of a 20" barrel, dropping to 2,848 in 16"
Your velocity of 2,767fps isn't all that surprising. (An effective barrellength of 15" would account for it completely)
Also... just a 4% drop in Powder Lot burn rate would also account for it, as would any slight variation in barrel internal dimensions.
Never chase the manufacturer's data ... it'll break your heart like a high-school Prom Queen.
entropy
Member
I don't know, that H20 is notoriously hard for even a magnum primer to ignite.
Hornady for years doesn't even test 55 gr. loads in an AR, only 26" bolt action. Lazy!! Your overall length is beyond what is recommended with the Hornady 55 FMJ. Hornady says 2.200" and I would seat them out to 2.230" and no longer. Hornady's 55 FMJ has a rounded blunt nose so seating them shorter than more sharply pointed 55 grain bullets is recommended. Your loads are .020-.050" too long. May make some difference in velocity. Not going to get to 3100 fps in a 16" barrel without pushing the safe limit. More often in the 2800-2900 fps with most powders but I'd think 3000 fps may be possible depending on powder, primer, and rifle. Some 55 FMJ's the recommended oal is 2.250" but not with Hornady's 55 FMJ-BT. To each his own method but I like a light crimp on bullets with a cannelure for my AR. No crimp on bullets without a cannelure.
Just so....
Still, that dihydrogen monoxide stuf'll kill you deader than a doornail if you're not careful w/ it.
Worse than hydroxylic acid.....
(See your
, and raise one )- Status
