As Apple Inc. (NASDAQ:AAPL) gears up for the launch of the iPhone 5S and its counterpart, the low cost iPhone 5C, analysts at Barclays have actually reduced their shipment forecasts for the two handsets in the third quarter of the year. In a report issued to investors, they cited slower than expected production ramp this month.

Apple iphone 5S

iPhone 5S, 5C assembled by Hon Hai, Pegatron

Barclays analysts Kirk Yang, Mark Chen, Dale Gai and Ava Chang issued a report to investors this week. They believe all of Apple Inc. (NASDAQ:AAPL)’s iPhone 5S handsets will be made by Hon Hai Precision Industry Co., Ltd (OTCMKTS:HNHPF) (TPE:2317). That includes both the TDD and FDD versions.

They believe that assembly of the iPhone 5C will be split between Hon Hai and Pegatron Corporation (TPE:4938) (OTCMKTS:PGTRF). They expect that Hon Hai will handle about 30 percent of the iPhone 5C, while Pegatron will handle the other 70 percent.

Expectations for the iPhone 5S, iPhone 5C

The analysts said they continue to expect that both of Apple’s new handsets will be unveiled on Sept. 10. They believe the iPhone 5S will come in black, white and gold. They expect to see storage options of 16, 32 and 64 GB, unlike others who are predicting that a 128 GB model will be available.

In addition to the new gold color offering, they’re looking for a fingerprint sensor, faster processor and dual LED flash. However, they predict the screen will remain at 4 inches in size, which is the same as that of the iPhone 5.

They believe the iPhone 5C will come in black, white, blue green and pink. They expect it to basically be the iPhone 5 with a plastic casing in these colors. As far as price for the low cost handset goes, they’re expecting it to be between $350 and $400 without a contract in the U.S.

iPhone 5S, 5C to have a slow launch

The analysts said yield rates for the iPhone 5S might be a problem for the handset’s early launch. They believe the problem with the fingerprint sensor which was noted earlier this year has been resolved, but they believe that volume production is increasing quite slowly.

In addition to low yield rates for the iPhone 5S, they suspect that some carriers might not want to over-order both of Apple Inc. (NASDAQ:AAPL)’s two models because of the handset’s 4-inch screen size. This is smaller than the mainstream 4.5 to 5-inch screen size, which they say the market is demanding right now. Their view is also consistent with comments from their camera component supply chain.

Barclays adjusts iPhone shipment forecasts

As a result, they cut their total third-quarter iPhone shipments forecast to between 28 million and 30 million units. Previously their estimate was for between 35 million and 37 million. However, they significantly raised their estimates for fourth-quarter shipments of the handsets. They increased their forecast to a range of 54 million to 56 million units from a range of 47 million to 49 million units.

The analysts also note though that their fourth-quarter forecast could fluctuate based on actual demand in the market as well as sell-through in September and October.