Compressed loads?

[jski]

This relates to another posting of mine. What are the effects of compressing the charge in a case?

I use 14-15 gr. of H110 in my .30 Carbine loads. This puts the powder close enough the the case mouth that you're compressing the charge. With heavier bullets this becomes even more of an issue because they're inserted further into the case.

So are compression loads problematic?

 

[redbullitt]

In 308 and similar cartridges, using varget and 748 etc, compressed loads are common at the top accuracy nodes. In the loading manuals many compressed loads are noted near the top as well. Loading density over 100 is going to be compressed. So, to me it simply depends on cartridge, powder, and bullet type. Some powders do not like being compressed, like trail boss for instance. Compression is not always a bad thing at all, but sometimes you can get too much and it becomes an issue.

I do not have any 30 carbine loading under my belt, so I cannot give you any specifics there.

 

[blue32]

In my experience with H110, albeit in 357 mag, the data tends to lean towards filling up the case. It may not be a compressed load per se but its close. A call to Hodgdon may be in order if you want to talk about specific bullets; 913-362-9455

 

[Jack B.]

Here is Sierra's opinion.

https://sierrabulletsblog.com/2013/03/14/compressed-loads/

 

[Walkalong]

Up to a point, yes, some compression is fine. Don't blow your self up with that .30 Carbine.

 

[hdwhit]

jski wrote:
I use 14-15 gr. of H110 in my .30 Carbine loads.

With any powder falling under the influence of gravity, the grains will dispose themselves in such a way that there are gaps between them. Geotechnical engineers refer to these gaps as a "void ratio". A compressed load uses the bullet as a tamp to press the grains closer together and thus reduce the void ratio. The practical effect of this is that when the primer is ignited, there is (in simplistic terms) less "space" for the "flame" of the primer to travel through in reaching all the grains of powder in the case. This can slow down the combustion of the powder, but in the case of H110 in 30 Carbine, a 15 grain load is only lightly compressed by a 110 grain bullet, so the effect should be negligible.

With heavier bullets this becomes even more of an issue...

• The Speer Manual #11 lists 14.0 grains of H110 as a maximum load with 110 grain bullets.
  
• Hornady #8 lists 14.9 as maximum with the same powder and bullet.
  
• Hodgdon's website lists 15.0 grains as maximum.

Using heavier bullets with 14-15 grain loadings of H110 is not something I would do unless I had first backed off to an 11-12 grain starting load and done a complete work-up from there - particularly if I was shooting it in a 70+ year old gun or a commercial carbine whose receiver, barrel, bolt, and operating rod may not have been hardened to G.I. specifications (unless I had had them checked out by a qualified gunsmith).

 

[243winxb]

Hodgdon's website shows no compressed loads for H110 rifle or pistol. But there OAL as listed may make the difference? Ball powder doesn't compress well, like some other powders.

Some other powder are shown as compressed, like 4227.

Note: The rifle section, at Hodgdon, has more powders listed for the 30 Carbine.

 

[Tinybob]

This relates to another posting of mine. What are the effects of compressing the charge in a case?

I use 14-15 gr. of H110 in my .30 Carbine loads. This puts the powder close enough the the case mouth that you're compressing the charge. With heavier bullets this becomes even more of an issue because they're inserted further into the case.

So are compression loads problematic?

I started using 14.6gr H110 and 110gr fmj for my Inland. This slightly compressed load works good for me, using Win SR primers. H110 does burn better in a full case anyway. I also used 15.8gr H110 and 90gr XTP. That load produced a 10 shot group of 1" at 50yds.

### This was in my rifle, not yours. Please be careful and work up from "start charge".###

 

[jski]

Tinybob, the loads I've been discussing in this posting are meant exclusively for my Blackhawk. It's a tank that can easily handle these kind pressures. It's built on the same frame as the 44 mag. Blackhawk.

I wouldn't ever try them in any of my M1 Carbines.

 

[jski]

I guess this boils down to: does powder behave differently when it's compressed? If yes (and assume it does), is it a function of how compressed it is?

 

[243winxb]

does powder behave differently when it's compressed?

Yes. But H110 is a flattened ball powder. Its already been rolled/smashed. This is why its not easy to compress or at all.

Stick powder like IMR 4350 types can be compressed. If the powder changes shape, smaller, the burn rate may change. Depending on how much its smashed.
http://www.firearmsid.com/Feature Articles/McCord_gunpowder/

Shape and size have a profound effect on the burning rate and power generation of a powder (Meyer 1987). Common particle shapes of smokeless propellants include balls, discs, perforated discs, tubes, perforated tubes, and aggregates

Many photo of powders and types. http://www.ilrc.ucf.edu/powders/sample_detail.php?powder_id=80

 

[tcoz]

15.0gr (slightly compressed) of H110 is the standard military load for 30 carbine 110gr FMJ. There are some reliable sources that recommend that as the one and only load and although I don't recommend it, they advise starting and stopping there. When I developed my load, I tested 13.5-15.0gr and arrived at 14.5. I'd say that 80% of M1 Carbine reloaders use somewhere in the 14-15gr load with the 110 FMJ bullet.

 

[Walkalong]

I use 14-15 gr. of H110 in my .30 Carbine loads. This puts the powder close enough the the case mouth that you're compressing the charge. With heavier bullets this becomes even more of an issue because they're inserted further into the case.

Tinybob, the loads I've been discussing in this posting are meant exclusively for my Blackhawk. It's a tank that can easily handle these kind pressures. It's built on the same frame as the 44 mag. Blackhawk.

I wouldn't ever try them in any of my M1 Carbines.

So are compression loads problematic?

No, but overloads are, no matter how much of a "tank" the gun is. Be careful out there.

 

[Tinybob]

How is the muzzle flash on your Blackhawk? I have a 6.5" in 357mag. A stout load of h110 makes a huge fire ball out of mine.

 

[jski]

Tinybob, I have .357 & .41 mags in addition to my .30 Carbine Blackhawk. All of my mag handguns (and I include the .30 Carbine as a mag) have a loud report and an impressive flash. If you consider that the cases of these 3 cartridges plus the .44 mag are almost of identical length, it's not all that surprising.

 

[Ironicaintit]

I found in 357 and 44 mags, as well as 30 carbine: H110 works it's best when loaded ever so slightly compressed. My carbine likes loads from 14.6-14.8 with 110gr bullets (Sierra FMJ or SP)

And then there's IMR4227, which isn't happy at all unless it's packed in tight (At least in 357, 44, and 30 carbine)